Victor R Baker
- Professor, Hydrology / Atmospheric Sciences
- Professor, Geosciences
- Professor, Planetary Sciences
- Regents Professor
- Professor, Global Change - GIDP
- Professor, Remote Sensing / Spatial Analysis - GIDP
- Member of the Graduate Faculty
Victor R. Baker is Regents’ Professor of Hydrology and Water Resources, Geosciences, and Planetary Sciences, University of Arizona. He received a B.S. in Geology from Rensselaer Polytechnic Institute in 1967 and a Ph.D. in Geology from the University of Colorado in 1971. After working as a hydrologist and geophysicist for the U.S. Geological Survey in New York and Colorado, he was on the faculty of the University of Texas at Austin from 1971-1981, advancing to the rank of Full Professor. In 1981 he moved to the Department of Geosciences, University of Arizona, first a Full Professor, and then in 1988 as one of The University of Arizona's first Regents' Professors. From 1996-2004 he was the Department Head of the Department of Hydrology and Water Resources, University of Arizona.
Baker has authored or co-authored more than 1000 scientific contributions, including 18 books, 400 research articles and chapters, more than 485 abstracts and short research reports (nearly all of them associated with papers that were presented at professional meetings, conferences, and workshops), 34 extended technical reports; 42 encyclopedia articles; 39 published book reviews; plus guidebook contributions and various other writings, including popular works in science. His research has concerned paleoflood hydrology (a field of study that he defined in the 1970s and 1980s); flood geomorphology; channels, valleys, and geomorphic features on Mars and Venus; catastrophic Pleistocene megaflooding in the northwestern U.S. and central Asia; history/philosophy of Earth and planetary sciences; and the interface of environmental science with public policy. Professor Baker has been President of the Geological Society of America (1998), Chair of the American Association for the Advancement of Science Section on Geology and Geography (1992-93 and 2008-2009), and President of the International Union for Quaternary Research Commission on Global Continental Paleohydrology (1995-99). Among his honors are Foreign Membership in the Polish Academy of Sciences (1994); Honorary Fellowship in the European Union of Geosciences (1999); the David Linton Award of the British Society for Geomorphology (1995); the Distinguished Scientist Award (2002) and Distinguished Career Award (2010), both from The Geological Society of America Quaternary Geology and Geomorphology Division; the Inaugural International Lectureship of the Geological Society of America (2012-2013), a Fulbright-Hays Senior Research Fellowship (1979-1880); an Indo-American Fellowship (1987-1988); and professional society Fellowships respectively in the American Geophysical Union, the American Association for the Advancement of Science, The Geological Society of America, and the British Society for Geomorphology. His work on megafloods has been featured in multiple television documentaries for PBS, BBC, and the National Geographic, Discovery and History Channels, including the 2005 NOVA production “Mystery of the Megaflood.”
- Inivited "Luminary Speaker"
- Prognostics and Health Management (PHM) Society, Fall 2019
- 50-Year Membership Recognition
- American Geophysical Union, Winter 2018
- The Geological Society of America, Fall 2018
- 50-Year Membership Status
- American Association for the Advancement of Science, Winter 2018
- Invited Keynote Speaker
- Geological Society of America, Rocky Mountain Section, Summer 2017
- One of the top SCIENTIFIC REPORTS articles
- Science Journal: Nature, SCIENTIFIC REPORTS, Spring 2017
- Outstanding Reviewer Status
- The journal GEOMORPHOLOGY, Spring 2015
- McMaster Visiting Scientist
- Bowling Green State University, Spring 2014
Dr. Baker’s research projects have been funded by the following agencies: National Science Foundation, N.A.S.A., U.S. Dept. of Interior, U.S. Geological Survey, U.S. Bureau of Reclamation, the National Geographic Society, National Oceanographic and Atmospheric Administration, and the Smithsonian Institu¬tion. Cumulative external funding for these projects totals approximately $5 million. Specific projects have con¬cerned paleoflood hydrologic studies in Texas, Utah, Arizona, northern Australia, Israel, Jordan, and India; flood geomorphology; volcanoes in Hawaii; channels, valleys, and geomorphic features on Mars; the geomorphology of Venus; river morphology in South America; Quaternary geology in Texas and the Colorado Plateau; karst hydrology in New York; and catas¬trophic Pleistocene floods in the northwestern U.S. and central Asia. Work is also conducted on the history/philosophy of Earth and planetary sciences, and on the interface of environmental science with public policy.
Professor Baker teaches undergraduate courses in "Geological Hazards" and “Earth” Our Watery Home.” His graduate courses include “Glacial and Quaternary Geology,” “Fluvial Geomorphology,” and “Flood Hydrometeorology and Hydroclimatology: Implications for Global Change and Extreme Hydrology"
DissertationHWRS 920 (Fall 2021)
Geologic HazardsGEOS 415 (Fall 2021)
ThesisGEOS 910 (Fall 2021)
Independent StudyGEOS 499 (Summer I 2021)
InternshipGEOS 393 (Summer I 2021)
DissertationHWRS 920 (Spring 2021)
Glacial+Quaternary GeolGEOS 453 (Spring 2021)
Glacial+Quaternary GeolGEOS 553 (Spring 2021)
ThesisGEOS 910 (Spring 2021)
DissertationHWRS 920 (Fall 2020)
Geologic HazardsGEOS 415 (Fall 2020)
Master's ReportGEOS 909 (Fall 2020)
DissertationHWRS 920 (Spring 2020)
GeosciencesGEOS 596H (Spring 2020)
Independent StudyGEOS 599 (Spring 2020)
DissertationHWRS 920 (Fall 2019)
Geologic HazardsGEOS 415 (Fall 2019)
ResearchGEOS 900 (Fall 2019)
DissertationHWRS 920 (Spring 2019)
Glacial+Quaternary GeolGEOS 453 (Spring 2019)
Glacial+Quaternary GeolGEOS 553 (Spring 2019)
ResearchGEOS 900 (Spring 2019)
DissertationHWRS 920 (Fall 2018)
Geologic HazardsGEOS 415 (Fall 2018)
Independent StudyGEOS 599 (Fall 2018)
DissertationHWRS 920 (Summer I 2018)
DissertationHWRS 920 (Spring 2018)
Independent StudyHWRS 599 (Spring 2018)
DissertationHWRS 920 (Fall 2017)
Geologic HazardsGEOS 415 (Fall 2017)
Independent StudyHWRS 599 (Fall 2017)
ResearchHWRS 900 (Fall 2017)
Earth: Our Watery HomeHWRS 170A1 (Spring 2017)
Glacial+Quaternary GeolGEOS 453 (Spring 2017)
Glacial+Quaternary GeolGEOS 553 (Spring 2017)
Independent StudyHWRS 599 (Spring 2017)
ResearchHWRS 900 (Spring 2017)
Geologic HazardsGEOS 415 (Fall 2016)
Independent StudyGEOS 499 (Fall 2016)
Independent StudyHWRS 599 (Fall 2016)
Independent StudyHWRS 599 (Spring 2016)
- Baker, V. R., Carling, P. A., & Herget, J. (2020). Catastrophic Freshwater Paleoflooding on Earth: A Global Perspective. Elsevier.More infoCarling, P.A., Baker, V.R., and Herget, J., editors, 2020, Catastrophic FreshwaterPaleoflooding on Earth: A Global Perspective: Elsevier (Earth-Science Reviews Special Volume).
- Baker, V. R. (2014). Paleohydrology: Benchmark Papers in Hydrology. Wallingford, U.K.: International Association of Hydrological Sciences Press.
- Baker, V. R. (2020). Global megaflood paleohydrology. In Palaeohydrology(pp 3-28). Heidelberg: Springer.More infoBaker, V.R., 2020, Global megaflood paleohydrology, in Herget, J. and Fontana, A., editors, Palaeohydrology. Geography of the Physical Environment: Springer, Heidelberg, p. 3-28.
- Baker, V. R., & Carling, P. A. (2020). Global Late Quaternary Megafloods. In Treatise on Geomorphology, 2nd Edition, Vol. 9, Fluvial Geomorphology(pp 1-8). Elsevier.More infoBaker, V.R., and Carling, P.A., 2020, Global Late Quaternary Megafloods, in Shroder, J. (Editor in Chief), Wohl, E.E. (Ed.), Treatise on Geomorphology, 2nd Edition, Vol. 9, Fluvial Geomorphology: Elsevier, 8 p.
- Pondrelli, M., Baker, V. R., Hauber, E., & Rossi, A. P. (2018). Geologic tools, Chapter 2. In Planetary Geology(pp 15-31). Heidelberg: Springer.More infoPondrelli, M., Baker, V.R., Hauber, E., and Rossi, A.P, 2018, Geologic tools, Chapter 2, in Rossi, A.P. and Van Gasselt, S., editors, Planetary Geology: Springer, Heidelberg, p. 15-31.
- Baker, V. R. (2017). Interdisciplinarity and the Earth sciences. In The Oxford Handbook of Interdisciplinarity(pp 88-100). Oxford: Oxford University Press.
- Baker, V. R. (2017). Paleofloods. In The International Encyclopedia of Geography: People, the Earth, Environment and Technology(pp 7 pages). Chichester, U.K: John Wiley and Sons. doi:10.1002/9781118786352.wbieg0104
- Baker, V. R. (2016). Pleistocene megaflood landscapes of the Channeled Scabland. In Exploring the Geology of the Inland Northwest(pp 1-73). Geological Society of America.More infoBaker, V.R., Bjornstad, B., Gaylord, D., Smith, G., Meyer, S., Alho, P., Breckenridge, R., Sweeney, M.R., and Zreda, M., 2016, Pleistocene megaflood landscapes of the Channeled Scabland, in Lewis, R.S., and Schmidt, K.L., eds., Exploring the Geology of the Inland Northwest: Geological Society of America Field Guide 41, Boulder, Colorado, p. 1-73.
- Baker, V. R. (2014). Chapter 3 – Victor Baker. In Peirce: 5 Questions(pp 19-35). Copenhagen, Denmark: Automatic Press/VIP.
- Baker, V. R. (2014). Epilogue: Skepticism versus fallibilism for achieving reliable science. In Global Land Ice Measurements from Space(pp 841-845). New York: Springer Praxis Books.
- Komatsu, G., Goto, K., Baker, V., Oguchi, T., Yuichi, S., Hayakawa, Y., Hitoshi, H., Saito, H., Pelletier, J., McGuire, L., & Iijima, Y. (2014). Effects of tsunami wave erosion on natural landscapes: Examples from the 2011 Tohoku-oki Tsunami. In Tsunami Events and Lessons Learned; Environmental and Societal Significance(pp 243-253). Heidelberg, Germany: Springer.More infoKomatsu, G., Goto, K., Baker, V.R., Oguchi, T., Yuichi S. Hayakawa, Y.S., Hitoshi Saito, H., Jon D. Pelletier, J.D., McGuire, L., and Iijima, Y., 2014, Effects of tsunami wave erosion on natural landscapes: Examples from the 2011 Tohoku-oki Tsunami, in Kontar, Y., Santiago-Fandiño, V., and Takahashi, T., editors, Tsunami Events and Lessons Learned; Environmental and Societal Significance. Springer, Heidelberg, p. 243-253.
- Mischna, M. A., Baker, V. R., Milliken, R., Richardson, M., & Lee, C. (2014). The role of obliquity, water vapor and trace gas greenhouses on the early martian climate. In Proceedings of the Fifth International Workshop on the Mars Atmosphere: Modelling and Observations(pp 1-5). Oxford, U.K.: Conference Proceedings.More infoMischna, M.A., Baker, V.R., Milliken, R., Richardson, M., and Lee, C., 2014, The role of obliquity, water vapor and trace gas greenhouses on the early martian climate, in Proceedings of the Fifth International Workshop on the Mars Atmosphere: Modelling and Observations: Oxford, U.K., January, 2014, 5 p.
- Baker, V. R. (2020). The modern evolution of geomorphology: Binghamton and personal perspectives, 1970-2019 and beyond. Geomorphology, 366(10668), 1-10. doi:doi.org/10.1016/j.geomorph.2019.02.028More infoBaker, V.R., 2020, The modern evolution of geomorphology: Binghamton and personal perspectives, 1970-2019 and beyond: Geomorphology, v. 366, 10668 DOI: https://doi.org/10.1016/jgeomorph.2019.02.028
- Baker, V. R., O'Connor, J. E., Waitt, R. B., Smith, L. N., Cannon, C. M., George, D. L., & Denlinger, R. P. (2020). The Missoula and Bonneville Floods—A review of ice-age megafloods in the Columbia River Basin. Earth-Science Reviews, 208(103181).More infoO’Connor, J.E., Baker, V.R., Waitt, R.B., Smith, L.N., Cannon, C.M., George, D.L., and Denlinger, R.P., 2020, The Missoula and Bonneville Floods—A review of ice- age megafloods in the Columbia River Basin: Earth-Science Reviews, v. 208, 103181. https://doi.org/10.1016/j.earscirev.2020.103181
- Baker, V. R., Rodriguez, A. J., Noe Dobrea, E., & Kargel, J. S. (2020). Oldest highlands of Mars may be massive dust fallout deposit. Nature Scientific Reports, 10(10347).More infoRodriguez, J.A.P., Noe Dobrea, E., Kargel, J.S., Baker, V.R., and 5 others, 2020, Oldest highlands of Mars may be massive dust fallout deposits: Nature Scientific Reports 10: 10347. https://doi.org/10.1038/s41598-020-64676-z
- Liu, T., Ji, L., Baker, V. R., Harden, T. M., & Cline, M. L. (2020). Holocene extreme paleofloods and their climatological context, Upper Colorado River Basin, USA. Progress in Physical Geography, 44(5), 727-745. doi:DOI: 10.1177/0309133320904038More infoLiu, T., Ji, L., Baker, V.R., Harden, T.M., and Cline, M.L., 2020, Holocene extreme paleofloods and their climatological context, upper Colorado River Basin, USA.Progress in Physical Geography, v. 44, p. 727-745. DOI: 10.1177/ 0309133320904038
- Rodriguez, A. P., Baker, V. R., Leonard, G., Kargel, J. S., Domingue, D., Berman, D. C., Banks, M., Zarroca, M., Linares, R., Marchi, S., Webster, K. D., & Sykes, M. (2020). The chaotic terrains of Mercury reveal a history of planetary volatile retention and loss in the innermost solar system. Nature Scientific Reports, 10(4737).More infoRodriguez, J.A.P., Leonard, G. J, Kargel, J.S, Domingue, D., Berman, D.C., Banks, M., Zarroca, M., Linares, R., Marchi, S., Baker, V.R., Webster, K.D., and Sykes, M., 2020, The chaotic terrains of Mercury reveal a history of planetary volatile retention and loss in the innermost solar system: Nature Scientific Reports, v. 10, article 4737.
- Blosch, G., & Baker, V. R. (2019). Twenty-three unsolved problems in hydrology (UPH)—a community perspective. Hydrological Science Journal, 64(10), 1141-1158.
- Fairen, A., Baker, V. R., & Others, . (2019). Planetary protection and the astrobiological exploration of Mars: Proactive steps in moving forward. Advances in Space Research. doi:https://doi.org/10.1016/j.asr.2019.01.011
- Fink, W., Baker, V. R., & Others, . (2019). Globally Optimal Rover Traverse Planner using Dijkstra’s Algorithm For Multi-Objective Deployment Scenarios. Planetary and Space Sciences. doi:doi.org/10.1016/j.pss.2019.104707More infoFink, W., Baker, V.R., Brooks, A. J.-W., Flammia, Dohm, J., Tarbell, M.A., in review, Globally Optimal Rover Traverse Planner using Dijkstra’s Algorithm For Multi-Objective Deployment Scenarios: Planetary and Space Sciences.
- Liu, T., Greenbaum, N., & Baker, V. R. (2019). Paleoflood hydrology of the lower Green River, upper Colorado River Basin, USA: An example of a naturalist approach to flood-risk analysis. Journal of Hydrology. doi:doi: https://doi.org/10.1016/j.jhydrol.2019.124337
- Rodriguez, A., Baker, V. R., & Others, . (2019). The 1997 Mars Pathfinder Spacecraft Landed on Spillover Flood Deposits from an Early Mars Inland Sea. Nature Scientific Reports, 9(4045). doi:doi:10.1038/s41598-019-39632-1
- Dohm, J. M., Maruyama, S., Kido, M., & Baker, V. R. (2018). A possible anorthositic continent of early Mars and the role of planetary size for the inception of Earth-like life. GEOSCIENCE FRONTIERS, 9(4), 1085-1098.
- Wilhelm, B., Ballasteros-Canovas, J. A., Macdonald, N., Toonen, W. H., Baker, V. R., & Others, . (2018). Interpreting historical, botanical, and geological evidence to aid preparations for future floods. Wiley Interdisciplinary Reviews: Water. doi:10.1002/wat2.1318More infoWilhelm, B., Ballesteros-Canovas, J., Macdonald, N., Toonen, W.H.J., Baker, V., et al., in review, Interpreting historical, botanical, and geological evidence to aid preparation for future floods: Wiley Interdisciplinary Reviews: Water.
- Baker, V. R. (2017). Debates - Hypothesis Testing in Hydrology: Pursuing Certainty Versus Pursuing Uberty. Water Resources Research, 53, 1770-1778.
- Balbas, A., Barth, A. M., Clark, P. U., Clark, J., Cafee, M., O'Connor, J. E., Baker, V. R., Konrad, K., & Bruce, B. (2017). 10Be dating of late-Pleistocene Megafloods and Cordilleran Ice Sheet Retreat in the Northwestern U.S. Geology, 45, 583-586.
- Latrubesse, E. M., Arima, E. Y., Dunne, T., Park, E., Baker, V. R., & Others, . (2017). Damming the rivers of the Amazon Basin. NATURE, 546, 363-369. doi:10.1038/nature22333More infoLatrubesse, E.M., Arima, E.Y., Dunne, T., Park, E., Baker, V.R., d’Horta, F.M, Wight, C., Wittman, F., Zuanon, J., Baker, P.A., Ribas, C.C., Norgaard, R.B., Filizola, N., Ansar, A., Flyvberg, B. and Stevaux, J. C., 2017: Nature, v. 546. p. 363-369.
- Baker, V. R., Bjornstad, B. N., Smith, G. A., Meyer, S. E., Alho, P., Breckenridge, R. M., Sweeney, M. R., & Zreda, M. G. (2016). Pleistocene megaflood landscapes of the Channeled Scabland. GSA Field Guides, 41, 1-73.
- Fairén, A. G., Dohm, J. M., Rodrugurez, A. P., Uceda, E. R., Kargel, J., Soare, H. J., Cleaves, D., Oehler, D., Schulze-Makuch, D., Essefi, E., Banks, M. E., Komatsu, G., Fink, W., Robbins, S., Yan, J., Miyamoto, H., Maruyama, S., & Baker, V. R. (2016). The Argyre region as a prime target for in situ astrobiological exploration of Mars.. Astrobiology, 16(2), 143-158. doi:10.1089/ast.2015.1396More infoFairén, A. G., J. M. Dohm, J. A. P. Rodríguez, E. R. Uceda, J. Kargel, R. Soare, H. J. Cleaves, D. Oehler, D. Schulze-Makuch, E. Essefi, M. E. Banks, G. Komatsu, W. Fink, S. Robbins, J. Yan, H. Miyamoto, S. Maruyama, and V. R. Baker, 2016, The Argyre region as a prime target for in situ astrobiological exploration of Mars. Astrobiology, v. 16, no. 2, p. 143-158. DOI: 10.1089/ast.2015.1396.
- Rettbert, P., Anesio, A., & Baker, V. (2016). Planetary protection and special regions on Mars—A suggestion for and updated definition. Astrobiology, 16(2), 119-125.More infoRettberg, P., Anesio, A., Baker, V., Baross, J., Caddy, S., Detis, E., Foreman, C., Hauber, E., Ori, G., Pearce, D., Renno, N., Ruvkun, G., Sattler, B., Sauders, M., Smith, D., Wagner, D. and Westall, F., 2016, Planetary protection and special regions on Mars—A suggestion for and updated definition: Astrobiology, v. 16, p. 119-125.
- Rodriguez, A. P., Fairen, A. G., Tanaka, K. L., Zarroca, M., Linares, R., Platz, T., Komatsu, G., Miyamoto, H., Kargel, J., Yan, J., Gulick, V., Higuchi, K., Baker, V. R., & Glines, N. (2016). Tsunami waves extensively resurfaced the shorelines of a receding, early Martian ocean. Scientific Reports, 6(25106). doi:10:1038/srep25106More infoRodríguez, J. A. P., Fairén, A.G., Tanaka, K.L., Zarroca, M., Linares, R., Platz, T., Komatsu,G., Miyamoto, H., Kargel, J., Yan, J., Gulick, V., Higuchi, K. Baker, V.R., Glines, N., 2016, Tsunami waves extensively resurfaced the shorelines of a receding, early Martian ocean: Scientific Reports. doi: 10:1038/srep25106.
- Rodríguez, A. P., Zarroca, M., Linares, R., Gulick, V., Weitz, C. M., Yan, J., Fairen, A. G., Miyamoto, H., Platz, T., Baker, V., Kargel, J., Glines, N., & Higuchi, K. (2016). Groundwater flow induced collapse and flooding in Noctis Labyrinthus, Mars.. Planetary and Space Science, 124, 1-14.More infoRodríguez, J. A. P., Zarroca, M., Linares, R., Gulick, V., Weitz, C.M., Jianguo Yan, Fairén, A.G., Miyamoto, H., Platz, T., Baker, V., Kargel, J., Glines, N., Higuchi, K., 2016, Groundwater flow induced collapse and flooding in Noctis Labyrinthus, Mars. Planetary and Space Science, v. 124, p. 1-14.
- Baker, V. R. (2015). Fluvial geomorphology of earth-like planetary surfaces: A review. Geomorphology, doi:10.1016/j.geomorph.2015.05.002.More infoBaker, V.R., Hamilton, C.W., Burr, D.M., Gulick, V., Komatsu, G., Luo, W., Rice, J.W., Jr., and Rodriguez, J.A.P., 2015, Fluvial geomorphology on earth-like planetary surfaces: A review: Geomorphology, v. 245, p. 149-182.
- Baker, V. R. (2015). Planetary geomorphology: Some historical/analytical perspectives. Geomorphology, 250, 8-17.
- Hayakawa, Y. S., Oguchi, T., Saito, H., Kobayashi, A., Baker, V. R., Pelletier, J., McGurie, L., Komatsu, G., & Goto, K. (2015). Geomorphic impacts of repeated tsunami waves in a coastal valley in northeastern Japan. Geomorphology, 242, 3-10.More infoHayakawa, Y. S., Oguchi, T., Saito, H., Kobayashi, A., Baker, V.R., Pelletier, J., McGuire, L., Komatsu, G. Goto, K., 2015, Geomorphic impacts of repeated tsunami waves in a coastal valley in northeastern Japan: Geomorphology, v. 242, p. 3-10.
- Komatsu, G., Baker, V. R., Arzhannikov, S. G., Gallagher, R., Arzhannikov, A. V., Murana, A., & Oguchi, T. (2015). Late Quaternary catastrophic flooding related to drainage reorganization and paleolake formation in northern Eurasia: A history of alternative hypotheses and indications for future research. International Geology Review, 58, 1693-1722. doi:10.1080/00206814.2015.1048314More infoKomatsu, G., Baker, V.R., Arzhannikov, S.G., Gallagher, R., Arzhannikov, A.V., Murana, A., and Oguchi, T., 2015, Late Quaternary catastrophic flooding related to drainage reorganization and paleolake formation in northern Eurasia: A history of alternative hypotheses and indications for future research: International Geology Review, v. 58, p. 1693-1722. doi: 10.1080/00206814.2015.1048314.
- Rodriguez, A. P., Kargel, J. S., Baker, V., Gulick, B., Berman, D. C., Fairen, A. G., Santiago, R. L., Hernandez, M. Z., Yan, J., Leonard, G., & Glines, N. (2015). Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?. Scientific Reports,, 5. doi:10.1038/srep13404More infoRodriguez, A. P., Kargel, J.S., Baker, V., Gulick, V., Berman, D.C., Fairen, A.G., Santiago, R. L., Hernandez, M.Z., Yan, J., Leonard, G., Glines, N., 2015, Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly? Scientific Reports, v. 5; doi: 10.1038/srep13404.
- Rodriguez, A. P., Platz, T., Gulick, V., Baker, V. R., Fairen, A. G., Kargel, J., Yan, J., Miyamoto, H., & Glines, N. (2015). Did the Martian outflow channels mostly form during the Amazonian Period?. Icarus, 257, 387-395.More infoRodriguez, J.A.P., Platz, T., Gulick, V., Baker, V.R., Fairén, A.G., Kargel, J., Yan, J. Miyamoto, H., and Glines, N, 2015, Did the Martian outflow channels mostly form during the Amazonian Period? Icarus, v. 257, p. 387-395.
- Rodriguiez, A. P., Leonard, G. J., Platz, T., Tanaka, K. L., Kargel, J. S., Fairen, A. G., Gulick, V. C., Baker, V. R., Glines, N., Miyamoto, H., Yan, J., & Oguma, M. (2015). New Insights into the Late Amazonian zonal shrinkage of the Martian south polar plateau. Icarus, 248, 407-411.More infoRodriguiez, A. P., Leonard, G.J., Platz, T., Tanaka, K.L., Kargel, J.S., Fairen, A.G., Gulick, V.C., Baker, V.R., Glines, N., Miyamoto, H., Yan, J., and Oguma, M., 2015, New Insights into the Late Amazonian zonal shrinkage of the Martian south polar plateau: Icarus, v. 248, p. 407-411.
- Baker, V. R. (2014). Terrestrial analogs, planetary geology, and the nature of geological reasoning. Planetary and Space Science, 95, 5-10.
- Baker, V. R. (2014). Uniformitarianism, earth system science, and geology. The Anthropocene, 5, 76-79.
- Fairén, A. G., Stokes, C. R., Davies, N. S., Schulze-Makuch, D., Rodriguez, J., Davila, A. F., Uceda, E. R., Dohm, J. M., Baker, V. R., Clifford, S. M., McKay, C. P., & Squyres, S. W. (2014). A cold hydrological system in Gale crater, Mars. Planetary and Space Science, 93-94, 101-118.More infoAbstract: Gale crater is a ~154-km-diameter impact crater formed during the Late Noachian/Early Hesperian at the dichotomy boundary on Mars. Here we describe potential evidence for ancient glacial, periglacial and fluvial (including glacio-fluvial) activity within Gale crater, and the former presence of ground ice and lakes. Our interpretations are derived from morphological observations using high-resolution datasets, particularly HiRISE and HRSC. We highlight a potential ancient lobate rock-glacier complex in parts of the northern central mound, with further suggestions of glacial activity in the large valley systems towards the southeast central mound. Wide expanses of ancient ground ice may be indicated by evidence for very cohesive ancient river banks and for the polygonal patterned ground common on the crater floor west of the central mound. We extend the interpretation to fluvial and lacustrine activity to the west of the central mound, as recorded by a series of interconnected canyons, channels and a possible lake basin. The emerging picture from our regional landscape analyses is the hypothesis that rock glaciers may have formerly occupied the central mound. The glaciers would have provided the liquid water required for carving the canyons and channels. Associated glaciofluvial activity could have led to liquid water running over ground ice-rich areas on the basin floor, with resultant formation of partially and/or totally ice-covered lakes in parts of the western crater floor. All this hydrologic activity is Hesperian or younger. Following this, we envisage a time of drying, with the generation of polygonal patterned ground and dune development subsequent to the disappearance of the surface liquid and frozen water. © 2014 Elsevier Ltd.
- Fink, W., Baker, V. R., Hamilton, C. W., Schulze-Makuch, D., & Tarbell, M. A. (2015). Autonomous exploration of planetary lava tubes using a multi-rover framework. IEEE Aerospace. doi:10.1109/AERO.2015.7119315
- Greenbaum, N., Harden, T. M., Baker, V. R., Weisheit, J., Cline, M. L., Porat, N., Halevi, R., & Dohernwend, J. (2014). A 2000-year natural record of magnitudes and frequencies for the largest upper Colorado River floods near Moab, Utah. Water Resources Research, 50, 5249-5269.More infoGreenbaum, N., Harden, T.M., Baker, V.R., Weisheit, J., Cline, M.L., Porat, N., Halevi, R.,and Dohernwend, J., 2014, A 2000-year natural record of magnitudes and frequencies for the largest upper Colorado River floods near Moab, Utah: Water Resources Research, v. 50, p. 5249-5269.
- Rodriguez, A. P., Gulick, V. C., Baker, V. R., Platz, T., Fairen, A. G., Miyamoto, H., Kargel, J., Rice, J., & Glines, N. (2014). Evidence for Middle Amazonian catastrophic flooding and glaciation on Mar. Icarus, 242, 202-210.More infoRodriguez, J.A.P., Gulick, V.C., Baker, V.R., Platz, T., Farien, A.G., Miyamoto, H., Kargel, J., Rice, J.W., and Glines, N., 2014, Evidence for Middle Amazonian catastrophic flooding and glaciation on Mars: Icarus, v. 242, p. 202-210.
- Baker, V. R. (2013). Rethinking the fabric of geology: An introduction. Special Paper of the Geological Society of America, 502, V-IX.
- Baker, V. R. (2013). Sinuous rivers. Proceedings of the National Academy of Sciences of the United States of America, 110(21), 8321-8322.More infoPMID: 23671095;PMCID: PMC3666737;
- Baker, V., & Baker, V. R. (2013). Sinuous rivers. Proceedings of the National Academy of Sciences of the United States of America, 110(21).
- Burr, D. M., Perron, J. T., Lamb, M. P., P., R., Collins, G. C., Howard, A. D., Sklar, L. S., Moore, J. M., Ádámkovics, M., Baker, V. R., Drummond, S. A., & Black, B. A. (2013). Fluvial features on Titan: Insights from morphology and modeling. Bulletin of the Geological Society of America, 125(3-4), 299-321.More infoAbstract: Fluvial features on Titan have been identified in synthetic aperture radar (SAR) data taken during spacecraft flybys by the Cassini Titan Radar Mapper (RADAR) and in Descent Imager/Spectral Radiometer (DISR) images taken during descent of the Huygens probe to the surface. Interpretations using terrestrial analogs and process mechanics extend our perspective on fluvial geomorphology to another world and offer insight into their formative processes. At the landscape scale, the varied morphologies of Titan's fluvial networks imply a variety of mechanical controls, including structural influence, on channelized flows. At the reach scale, the various morphologies of individual fluvial features, implying a broad range of fluvial processes, suggest that (paleo-)flows did not occupy the entire observed width of the features. DISR images provide a spatially limited view of uplands dissected by valley networks, also likely formed by overland flows, which are not visible in lowerresolution SAR data. This high-resolution snapshot suggests that some fluvial features observed in SAR data may be river valleys rather than channels, and that uplands elsewhere on Titan may also have fine-scale fluvial dissection that is not resolved in SAR data. Radar-bright terrain with crenulated bright and dark bands is hypothesized here to be a signature of fine-scale fluvial dissection. Fluvial deposition is inferred to occur in braided channels, in (paleo)lake basins, and on SAR-dark plains, and DISR images at the surface indicate the presence of fluvial sediment. Flow sufficient to move sediment is inferred from observations and modeling of atmospheric processes, which support the inference from surface morphology of precipitation-fed fluvial processes. With material properties appropriate for Titan, terrestrial hydraulic equations are applicable to flow on Titan for fully turbulent flow and rough boundaries. For low-Reynolds-number flow over smooth boundaries, however, knowledge of fluid kinematic viscosity is necessary. Sediment movement and bed form development should occur at lower bed shear stress on Titan than on Earth. Scaling bedrock erosion, however, is hampered by uncertainties regarding Titan material properties. Overall, observations of Titan point to a world pervasively influenced by fluvial processes, for which appropriate terrestrial analogs and formulations may provide insight. © 2013 Geological Society of America.
- Dohm, J. M., Miyamoto, H., Maruyama, S., Baker, V. R., Anderson, R. C., Hynek, B. M., Robbins, S. J., Ori, G., Komatsu, G., R., M., Soare, R. J., Mahaney, W. C., Kim, K. J., & Hare, T. M. (2013). Mars evolution. Mars: Evolution, Geology and Exploration, 1-33.More infoAbstract: An overarching geologic hypothesis, GEOMARS, coherently explains many aspects of the geological history of Mars. This includes ancient geologic terrains that comprise mountain ranges, structurally-controlled basins, highly degraded promontories, magnetic anomalies, and basin-containing stacked sequences of sedimentary deposits. In addition, the theory also clarifies an ever increasingly realized mineralogically diverse planet, marine-, lacustrine-, fluvial-, eolian-, and glacial-sculpted landscapes, and superplumes that have dominated the geologic, hydrologic, and climatic histories for more than 3.5 Ga until the present. The hypothesis comprises eight major stages of martian geological evolution (from oldest to youngest): Stage 1 - shortly after accretion, Mars differentiates to a liquid metallic core, a mantle boundary (MBL) of high-pressure silicate mineral phases, upper mantle, magma ocean, thin komatiitic crust, and convecting steam atmosphere; Stage 2- Mars cools to condense its steam atmosphere and transforms its mode of mantle convection to plate tectonism; subduction of water-rich oceanic crust initiates arc volcanism and transfers water, carbonates, and sulfates to the mantle; Stage 3 - the core dynamo initiates, with the associated magnetosphere and possible photosynthetic production of oxygen; Stage 4 -accretion of thickened, continental crust and subduction of hydrated oceanic crust to the mantle boundary layer and lower mantle of Mars continues; Stage 5 - the core dynamo stops during Noachian heavy bombardment but plate tectonism continues; Stage 6 - large basin-forming impacts result in Hellas, Argyre, Isidis, and Chryse; Stage 7-plate tectonism terminates and Tharsis superplume (~between 4.0 and 3.8Ga) initiates, and Stage 8 - the superplume phase (stagnant-lid regime) of martian planetary evolution with episodic phases of volcanism, water outflows, and related transient hydrological cycling as well as climate and environmental change which interrupts prevailing ice-house conditions. This portrayal of the geological evolution of Mars, as a testable hypothesis, is highlighted through the geologic provinces of Mars and their special attributes. The provinces are (mostly from oldest to youngest, as there is an overlap in relative age among several of the provinces): the ancient southern highland province, including Terra Cimmeria, Terra Sirenum, Arabia Terra, Zanthe Terra, and the mountains ranges, Thaumasia highlands and Coprates rise, as well as the younger Hellas-Argyre province, Tharsis and other volcanic provinces such as Elysium rise, Malea Planum, Hadriaca and Tyrrhena Mons, Apollinaris Mons, and Syrtis Major, the northern plains, and the Tharsis/Elysium corridor. © 2013 by Nova Science Publishers, Inc. All rights reserved.
- Mischna, M. A., Baker, V., Milliken, R., Richardson, M., & Lee, C. (2013). Effects of obliquity and water vapor/trace gas greenhouses in the early martian climate. Journal of Geophysical Research E: Planets, 118(3), 560-576.More infoAbstract: We explore possible mechanisms for the generation of warm, wet climates on early Mars as a result of greenhouse warming by both water vapor and periodic volcanic trace emissions. The presence of both water vapor (a strong greenhouse gas) and other trace greenhouse gases (such as SO2) in a predominantly CO2 atmosphere may act, under certain conditions, to elevate surface temperatures above the freezing point of liquid water, at least episodically. Variations in obliquity are explored to investigate whether these periodic variations in insolation at Mars can broaden the regions or seasons where warm temperatures can exist. We use the Mars Weather Research and Forecasting general circulation model to perform several simulations of the conditions of the early martian atmosphere containing these gases and find global temperatures to be cooler than the elevated levels suggested by at least one recent study by Johnson et al. (2008). While achieving temperatures above 273 K globally remains challenging, the additional warming by greenhouse gases under certain obliquity states can permit for widespread seasonally warm conditions, which can help to explain the presence of fluvial surface features (e.g., valley networks) and hydrous minerals of post-Noachian age, a period when alternate methods do not convincingly explain the sustainability of liquid water. Furthermore, we find that global warming can be achieved with the presence of a darker surface globally, which is consistent with both widespread exposure of unweathered basaltic bedrock or the presence of a large surface ocean or sea. Key Points Obliquity state and volcanic gases together enhance greenhouse warming. Periodic greenhouse events in Mars history explain observed fluvial features. Dark surfaces, consistent with liquid water, enhance surface warming ©2013. American Geophysical Union. All Rights Reserved.
- Alexis, J., Bourke, M., Tanaka, K. L., Miyamoto, H., Kargel, J., Baker, V., Fairén, A. G., Davies, R. J., Bridget, L., Santiago, R. L., Hernndez, M. Z., & Berman, D. C. (2012). Infiltration of Martian outflow channel floodwaters into lowland cavernous systems. Geophysical Research Letters, 39(22).More infoAbstract: The hydrosphere of Mars has remained mostly concealed within the subsurface for the past ∼3.5 Gyr. Localized rupturing of the permafrost-capped crust led to voluminous groundwater discharges that carved some of the largest known channels in the solar system. However, our knowledge of the nature of the flows and their ultimate fate remains incomplete, partly because diagnostic landforms at outflow channel termini have been largely destroyed or buried. The Hebrus Valles outflow channels were excavated by fluid discharges that emanated from two point sources, and they mostly terminate in systems of fractures and depressions within the northern plains. Our investigation indicates that outflow channel floodwaters were captured and reabsorbed into the subsurface in zones where caverns developed within the northern plains. These findings imply that the study region comprises the only known location in the Martian northern lowlands where the fate of outflow channel discharges can be assessed with confidence. We propose that evacuation of subsurface materials via mud volcanism was an important process in cavern formation. Our conceptual model provides a hypothesis to account for the fate of sediments and fluids from some of the Martian outflow channels. It also reveals a mechanism for lowland cavern formation and upper crustal volatile enrichment after the development of the Martian global cryosphere.
- Baker, V. R. (2012). Terrestrial analogs, planetary geology, and the nature of geological reasoning. Planetary and Space Science.More infoAbstract: Analogical reasoning is critical to planetary geology, but its role can be misconstrued by those unfamiliar with the practice of that science. The methodological importance of analogy to geology lies in the formulation of genetic hypotheses, an absolutely essential component of geological reasoning that was either ignored or denigrated by most 20th century philosophers of science, who took the theoretical/ experimental methodology of physics to be the sole model for all of scientific inquiry. Following the seminal 19th century work of Grove Karl Gilbert, an early pioneer of planetary geology, it has long been recognized that broad experience with and understanding of terrestrial geological phenomena provide geologists with their most effective resource for the invention of potentially fruitful, working hypotheses. The actions of (1) forming such hypotheses, (2) following their consequences, and (3) testing those consequences comprise integral parts of effective geological practice in regard to the understanding of planetary surfaces. Nevertheless, the logical terminology and philosophical bases for such practice will be unfamiliar to most planetary scientists, both geologists and nongeologists. The invention of geological hypotheses involves both inductive inferences of the type Gilbert termed "empiric classification" and abductive inferences of a logical form made famous by the 19th century American logician Charles Sanders Peirce. The testing and corroboration of geological hypotheses relies less on the correspondence logic of theoretical/ experimental sciences, like physics, and more on the logic of consistency, coherence, and consilience that characterizes the investigative and historical sciences of interpretation exemplified by geology. © 2012 Elsevier Ltd. All rights reserved.
- Baker, V. R. (2011). Global planetary change and catastrophic earth-surface evolution: Implications for modern geomorphological research. Geographia Polonica, 84(SUPPL. 2), 5-14.More infoAbstract: Current international programs of global planetary change research overemphasize the role of analysis as manifested in the idealized predictions of mathematical models, a strategy that contains potential flaws both scientifically and as a matter of public policy. Similar methodological problems have impeded progress in understanding the catastrophic processes that affect landforms and landscapes at various spatial scales. An increased emphasis on synthetic scientific reasoning through the use of natural indexical signs can provide a more balanced scientific approach to advancing understanding in both these areas.
- Fairén, A. G., Dohm, J. M., Baker, V. R., Thompson, S. D., Mahaney, W. C., Herkenhoff, K. E., Alexis, J., Davila, A. F., Schulze-Makuch, D., Ramy, M., Uceda, E. R., Amils, R., Miyamoto, H., Kim, K. J., Anderson, R. C., & McKay, C. P. (2011). Meteorites at Meridiani Planum provide evidence for significant amounts of surface and near-surface water on early Mars. Meteoritics and Planetary Science, 46(12), 1832-1841.More infoAbstract: Six large iron meteorites have been discovered in the Meridiani Planum region of Mars by the Mars Exploration Rover Opportunity in a nearly 25km-long traverse. Herein, we review and synthesize the available data to propose that the discovery and characteristics of the six meteorites could be explained as the result of their impact into a soft and wet surface, sometime during the Noachian or the Hesperian, subsequently to be exposed at the Martian surface through differential erosion. As recorded by its sediments and chemical deposits, Meridiani has been interpreted to have undergone a watery past, including a shallow sea, a playa, an environment of fluctuating ground water, and/or an icy landscape. Meteorites could have been encased upon impact and/or subsequently buried, and kept underground for a long time, shielded from the atmosphere. The meteorites apparently underwent significant chemical weathering due to aqueous alteration, as indicated by cavernous features that suggest differential acidic corrosion removing less resistant material and softer inclusions. During the Amazonian, the almost complete disappearance of surface water and desiccation of the landscape, followed by induration of the sediments and subsequent differential erosion and degradation of Meridiani sediments, including at least 10-80m of deflation in the last 3-3.5Gy, would have exposed the buried meteorites. We conclude that the iron meteorites support the hypothesis that Mars once had a denser atmosphere and considerable amounts of water and/or water ice at and/or near the surface. © The Meteoritical Society, 2011.
- Jones, A. P., McEwen, A. S., Tornabene, L. L., Baker, V. R., Melosh, H. J., & Berman, D. C. (2011). A geomorphic analysis of Hale crater, Mars: The effects of impact into ice-rich crust. Icarus, 211(1), 259-272.More infoAbstract: Hale crater, a 125×150km impact crater located near the intersection of Uzboi Vallis and the northern rim of Argyre basin at 35.7°S, 323.6°E, is surrounded by channels that radiate from, incise, and transport material within Hale's ejecta. The spatial and temporal relationship between the channels and Hale's ejecta strongly suggests the impact event created or modified the channels and emplaced fluidized debris flow lobes over an extensive area (>200,000km2). We estimate ∼1010m3 of liquid water was required to form some of Hale's smaller channels, a volume we propose was supplied by subsurface ice melted and mobilized by the Hale-forming impact. If 10% of the subsurface volume was ice, based on a conservative porosity estimate for the upper martian crust, 1012m3 of liquid water could have been present in the ejecta. We determine a crater-retention age of 1Ga inside the primary cavity, providing a minimum age for Hale and a time at which we propose the subsurface was volatile-rich. Hale crater demonstrates the important role impacts may play in supplying liquid water to the martian surface: they are capable of producing fluvially-modified terrains that may be analogous to some landforms of Noachian Mars. © 2010 Elsevier Inc.
- Komatsu, G., Ori, G. G., Cardinale, M., Dohm, J. M., Baker, V. R., Vaz, D. A., Ishimaru, R., Namiki, N., & Matsui, T. (2011). Roles of methane and carbon dioxide in geological processes on Mars. Planetary and Space Science, 59(2-3), 169-181.More infoAbstract: We discuss in this paper possible roles of methane and carbon dioxide in geological processes on Mars. These volatiles in the martian crust may migrate upward from their sources either directly or via various traps (structural, sedimentary, ground ice, gas hydrates). They are then likely emitted to the atmosphere by seepage or through diverse vent structures. Though gas hydrates have never been directly detected on Mars, theoretical studies favor their presence in the crust and polar caps; they could have played an important role as significant gas reservoirs in the subsurface. The martian gas hydrates would possibly be a binary system of methane and carbon dioxide occupying clathrate cavities. Landforms such as mud volcanoes with well-known linkage to gas venting are extensively distributed on Earth, and methane is the primary gas involved. Thus, identification of these landforms on Mars could suggest that methane and possibly carbon dioxide have contributed to geological processes of the planet. For example, we present a newly identified field in Chryse Planitia where features closely resembling terrestrial mud volcanoes occur widely, though with no observable activity. We also present results of a preliminary search for possible recent or present-day, methane-emission zones in the regions over which enrichments of atmospheric methane have been reported. © 2010 Elsevier Ltd.
- Pelletier, J. D., & Baker, V. R. (2011). The role of weathering in the formation of bedrock valleys on Earth and Mars: A numerical modeling investigation. Journal of Geophysical Research E: Planets, 116(11).More infoAbstract: Numerical models of bedrock valley development generally do not include weathering explicitly. Nevertheless, weathering is an essential process that acts in concert with the transport of loose debris by seepage and runoff to form many bedrock valleys. Here we propose a numerical model for bedrock valley development that explicitly distinguishes weathering and the transport of loose debris and is capable of forming bedrock valleys similar to those observed in nature. In the model, weathering rates are assumed to increase with increasing water availability, a relationship that data suggest likely applies in many water-limited environments. We compare and contrast the model results for cases in which weathering is the result of runoff-induced infiltration versus cases in which it is the result of seepage- or subsurface-driven flow. The surface flow-driven version of our model represents an alternative to the stream-power model that explicitly shows how rates of both weathering and the transport of loose debris are related to topography or water flow. The subsurface flow-driven version of our model can be solved analytically using the linearized Boussinesq approximation. In such cases the model predicts theater-headed valleys that are parabolic in planform, a prediction broadly consistent with the observed shapes of theater-headed bedrock valleys on Mars that have been attributed to a combination of seepage weathering and episodic removal of weathered debris by runoff, seepage, and/or spring discharge. Copyright 2011 by the American Geophysical Union.
- Alho, P., Baker, V. R., & Smith, L. N. (2010). Paleohydraulic reconstruction of the largest Glacial Lake Missoula draining(s). Quaternary Science Reviews, 29(23-24), 3067-3078.More infoAbstract: Glacial Lake Missoula (GLM) was the source of Earth's largest known peak flood discharges onto the Channeled Scabland, northwestern United States. The original studies of GLM were based on geomorphological mapping of lake sediments and shorelines. More recently, studies have emphasized the computational fluid dynamics of downstream megaflood routing and characteristics in the Channeled Scabland and adjacent areas. However, actual details of the lake-draining processes GLM have received little scientific attention. In this paper, we employ two-dimensional hydraulic modelling to understand the paleoflow conditions for different scenarios of draining GLM at its highest stands. Values are calculated for three GLM drainage hydrographs (2.6; 13; 17×106m3s-1) that previous studies had estimated for outlet flows. Consistent with regional mapping and with the original interpretation of fluvial geomorphology by other studies, the modelling shows that lake silt sequences in the gorges of GLM must postdate the most highly energetic outburst events from the lake. This is because the flows generated in the lake by megaflood outflows are sufficiently energetic to erode any accumulated silt deposits. In contrast, the gravels underlying the silts in these zones include boulder-sized clasts, large-scale cross stratification, and 70-100m-high bars forms, all of which indicate very high-energy flood flow conditions. The modelling also shows that the paleohydraulic conditions which developed in the lake basin during the largest megaflood outflows would be capable of accounting for the observed bedrock scour at Rainbow Lake Pass, various " high eddy deposits" (eddy bars of flood gravel) in gorges, and the " giant ripple marks" (subaqueous gravel dunes) that were classically described in the 1940s. Previous studies interpreted the glacial lake silt/rhythmites and related deposits, such as the Ninemile Section, as evidence for numerous fillings and drainings of GLM. Our modelling suggests that these inferred events must have been relatively low in energy and magnitude relative to the earlier outburst(s) that emplaced the flood gravels, subaqueous gravel dunes, and scabland-like erosion surfaces. © 2010 Elsevier Ltd.
- Baker, V. R. (2010). Channeled scablands: A megaflood landscape. Geomorphological Landscapes of the World, 21-28.More infoAbstract: The Channeled Scabland of east-central Washington in the USA is a complex of anastomosing, rock-cut fluvial channels, rock basins, cataracts, streamlined loess hills, and immense gravel bars. It was all produced by cataclysmic erosion and deposition from Pleistocene megaflooding derived from the margins of the Cordilleran Ice Sheet that covered much of the mountainous northwestern part of North America. © 2010 Springer Science+Business Media B.V.
- Baker, V. R. (2010). Foreword. Lakes on Mars, xv-xx.
- Brown, K. B., McIntosh, J. C., Baker, V. R., & Gosch, D. (2010). Isotopically-depleted late Pleistocene groundwater in Columbia River Basalt aquifers: Evidence for recharge of glacial Lake Missoula floodwaters?. Geophysical Research Letters, 37(21).More infoAbstract: Late Pleistocene outburst flooding of ice-dammed glacial Lake Missoula, and possible discharge from the Cordilleran Ice Sheet (CIS), catastrophically altered the northwestern United States landscape, yet little is known about potential infiltration of flood waters into the subsurface. This study provides compelling evidence for the presence of late Pleistocene CIS-related recharge waters in the Columbia River Basalt Aquifers (CRBAs) in central Washington. CRBA groundwaters with corrected 14C ages from 15.7 and 33.3 k yrs BP (during periods of flood events) have anomalously low δ18O values (-18.9 to -17.6‰), compared to late Pleistocene soil waters (-16.1 to -13.4‰) and modern precipitation in the region (average -15.9‰), consistent with CIS-related meltwater recharge. These results have implications for our understanding of megaflood phenomena on earth and Mars. © 2010 by the American Geophysical Union.
- Brown, K., Mcintosh, J. C., Baker, V. R., & Gosch, D. (2010). Isotopically-depleted Late Pleistocene groundwater in Columbia River Basalts: evidence for recharge of Glacial Lake Missoula floodwaters?. Geophysical Research Letters, 37(L21402), doi:10.1029/2010GL044992.
- Harden, T., Macklin, M. G., & Baker, V. R. (2010). Holocene flood histories in south-western USA. Earth Surface Processes and Landforms, 35(6), 707-716.More infoAbstract: River basins in south-western USA are some of the most extensively studied arid land fluvial systems in the world. Since the early 1960s their hydro-climatic histories have been reconstructed from the analysis of alluvial cut-and-fill cycles, while from the late 1970s there have been investigations of slackwater deposits and palaeostage indicators for large floods in stable-boundary bedrock reaches. However, no studies have regionally integrated Holocene fluvial histories from these two different types of fluvial environments. The current study combines the alluvial archive with flood records from bedrock reaches to generate a probability-based 12,000 year record of flooding in south-western USA. Using more than 700 14C-dated fluvial units, the analysis produces a high resolution (centennial) flood record. Seven episodes of increased flooding occurred at 11,250-10,400, 8800-8350, 8230-7600, 6700-5700, 5600-4820, 4550-3320 and 2000-0 cal. BP. Bedrock reaches are found to record more frequent floods during the middle to late Holocene, while in alluvial rivers more flood units are dated to the early and middle Holocene. These differences are primarily the result of selective preservation with alluvial reaches tending to erode during periods characterised by very large floods. Episodes of major Holocene flooding recorded in slackwater deposits within bedrock systems correspond with periods of increased precipitation in the region and lower temperatures. In contrast, within alluvial rivers above-average flooding probabilities, as well as regionally extensive channel entrenchment episodes, match with reduced annual pre-cipitation and lower temperatures. The results of this study clearly demonstrate the value of the Holocene fluvial archive for reconstructing regional, short-term hydro-climatic change in south-western USA. © 2010 John Wiley & Sons, Ltd.
- Baker, V. R. (2009). Charles S. Peirce and the "Light of Nature. Memoir of the Geological Society of America, 203, 259-266.More infoAbstract: The American polymath and logician Charles S. Peirce (1839-1914) spent much of his professional career working on geodetic measurements. Nevertheless, his very original studies of scientific inference have considerable relevance to geology. Particularly important influences on his views derive from his avid studies of the Scientific Revolution and the Enlightenment, notably the writings of Galileo Galilei (1564-1642) and Immanuel Kant (1724-1804). From Kant, Peirce derived an architectonic and categorical approach to philosophy. Following the example of the Cambridge mineralogist William Whewell (1794-1866), Peirce pursued the history of science in order to uncover the logic of scientific inquiry. His original reading of Galileo revealed that scholar's reliance upon il lume naturale ("the Light of Nature") as a guide toward the selection of potentially productive hypotheses from among the many that might be posed in regard to scientific explanation. This principle underpins Peirce's famous and controversial notion of abduction, or retroduction, i.e., informed guessing, as critical to scientific inquiry. The instinctive tendency of the experienced and informed scientist to "guess right" is essential to the historically demonstrated success of science. © 2009 The Geological Society of America.
- Baker, V. R. (2009). Megafloods and global paleoenvironmental change on Mars and Earth. Special Paper of the Geological Society of America, 453, 25-36.More infoAbstract: The surface of Mars preserves landforms associated with the largest known water floods. While most of these megafloods occurred more than 1 Ga ago, recent spacecraft images document a phase of outburst flooding and associated volcanism that seems no older than tens of millions of years. The megafloods that formed the Martian outflow channels had maximum discharges comparable to those of Earth's ocean currents and its thermohaline circulation. On both Earth and Mars, abrupt and episodic operations of these megascale processes have been major factors in global climatic change. On relatively short time scales, by their influence on oceanic circulation, Earth's Pleistocene megafloods probably (1) induced the Younger Dryas cooling of 12.8 ka ago, and (2) initiated the Bond cycles of ocean-climate oscillation with their associated Heinrich events of "iceberg armadas" into the North Atlantic. The Martian megafloods are hypothesized to have induced the episodic formation of a northern plains "ocean," which, with contemporaneous volcanism, led to relatively brief periods of enhanced hydrological cycling on the land surface (the "MEGAOUTFLO Hypothesis"). This process of episodic short-duration climate change on Mars, operating at intervals of hundreds of millions of years, has parallels in the Neoproterozoic glaciation of Earth (the "Snowball Earth Hypothesis"). Both phenomena are theorized to involve abrupt and spectacular planet-wide climate oscillations, and associated feedbacks with ocean circulation, landsurface weathering, glaciation, and atmospheric carbon dioxide. The critical factors for megascale environmental change on both Mars and Earth seem to be associated tectonics and volcanism, plus the abundance of water for planetary cycling. Some of the most important events in planetary history, including those of the biosphere, seem to be tied to cataclysmic episodes of massive hydrological change. © 2009 The Geological Society of America.
- Baker, V. R. (2009). The channeled scabland: A retrospective. Annual Review of Earth and Planetary Sciences, 37, 393-411.More infoAbstract: The Channeled Scabland of east-central Washington in the United States is a complex of anastomosing rock-cut fluvial channels, cataracts, loess islands, rock basins, broad gravel deposits, and immense gravel bars. In the 1920s, J Harlen Bretz demonstrated that the Channeled Scabland formed by cataclysmic erosion and deposition from Pleistocene megaflooding derived from the margins of the Cordilleran Ice Sheet, particularly glacial Lake Missoula in western Montana and northern Idaho. Studies of this region and the high-energy flood processes that generated it are stimulating (a) discoveries of similar megaflood-related landscapes around the world and on Mars, (b) enhanced understanding of the processes involved in the fluvial erosion of bedrock, and (c) the use of paleoflood indicators for understanding the magnitudes and frequency of flooding. Copyright © 2009 by Annual Reviews. All rights reserved.
- Banks, M. E., Lang, N. P., Kargel, J. S., McEwen, A. S., Baker, V. R., Grant, J. A., Pelletier, J. D., & Strom, R. G. (2009). An analysis of sinuous ridges in the southern Argyre Planitia, Mars using HiRISE and CTX images and MOLA data. Journal of Geophysical Research E: Planets, 114(9).More infoAbstract: A suite of sinuous ridges with branching and braided morphologies forms an anastomosing network in southern Argyre Planitia, Mars. Several modes of origin have been proposed for the Argyre ridges. Imagery from the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) aboard Mars Reconnaissance Orbiter (MRO) and Mars Orbiter Laser Altimeter (MOLA) topographic data sets from Mars Global Surveyor (MGS) are used to constrain processes involved in formation of the Argyre ridges. We find the characteristics of the ridges and associated layered deposits consistent with glaciofluvial-lacustrine processes and conclude that the ridges are most likely eskers. In particular, variations in ridge height appear to be related to the surrounding surface slope; ridge height increases with descending slopes and decreases with ascending slopes. This characteristic is observed in terrestrial eskers and is related to subice flow processes. The nature of some eroding beds in the ridges suggests induration. If the Argyre ridges are indeed eskers, the southern Argyre basin was once covered by the margin of a large, thick, stagnating or retreating ice deposit that extended for hundreds of kilometers or more. During ridge formation, water flowed on top, within, or beneath the ice deposit; the continuity and preservation of the ridges suggests that flow was primarily at the base of the ice. The dimensions (up to hundreds of meters tall and several kilometers wide), aspect ratio, and extent (hundreds of kilometers) of the ridges, as well as preliminary calculations of discharge, suggest that a significant amount of water was available. Copyright 2009 by the American Geophysical Union.
- Chien, S., Tran, D., Schaffer, S., Rabideau, G., Davies, A. G., Doggett, T., Greeley, R., Felipe, I. p., Baker, V., Doubleday, J., Castano, R., Mandl, D., Frye, S., Ong, L., Rogez, F., & Oaida, B. (2009). Onboard classification of hyperspectral data on the Earth Observing One mission. WHISPERS '09 - 1st Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing.More infoAbstract: Remote-sensed hyperspectral data represents significant challenges in downlink due to its large data volumes. This paper describes a research program designed to process hyperspectral data products onboard spacecraft to (a) reduce data downlink volumes and (b) decrease latency to provide key data products (often by enabling use of lower data rate communications systems). We describe efforts to develop onboard processing to study volcanoes, floods, and cryosphere, using the Hyperion hyperspectral imager and onboard processing for the Earth Observing One (EO-1) mission as well as preliminary work targeting the Hyperspectral Infrared Imager (HyspIRI) mission. © 2009 IEEE.
- Dohm, J. M., Anderson, R. C., Williams, J., Ruiz, J., McGuire, P. C., Buczkowski, D. L., Wang, R., Scharenbroich, L., Hare, T. M., Connerney, J. E., Baker, V. R., Wheelock, S. J., Ferris, J. C., & Miyamoto, H. (2009). Claritas rise, Mars: Pre-Tharsis magmatism?. Journal of Volcanology and Geothermal Research, 185(1-2), 139-156.More infoAbstract: Claritas rise is a prominent ancient (Noachian) center of tectonism identified through investigation of comprehensive paleotectonic information of the western hemisphere of Mars. This center is interpreted to be the result of magmatic-driven activity, including uplift and associated tectonism, as well as possible hydrothermal activity. Coupled with its ancient stratigraphy, high density of impact craters, and complex structure, a possible magnetic signature may indicate that it formed during an ancient period of Mars' evolution, such as when the dynamo was in operation. As Tharsis lacks magnetic signatures, Claritas rise may pre-date the development of Tharsis or mark incipient development, since some of the crustal materials underlying Tharsis and older parts of the magmatic complex, respectively, could have been highly resurfaced, destroying any remanent magnetism. Here, we detail the significant characteristics of the Claritas rise, and present a case for why it should be targeted by the Mars Odyssey, Mars Reconnaissance Orbiter, and Mars Express spacecrafts, as well as be considered as a prime target for future tier-scalable robotic reconnaissance. © 2009 Elsevier B.V.
- Dohm, J. M., Williams, J., Anderson, R. C., Ruiz, J., McGuire, P. C., Komatsu, G., Davila, A. F., Ferris, J. C., Schulze-Makuch, D., Baker, V. R., Boynton, W. V., Fairén, A. G., Hare, T. M., Miyamoto, H., Tanaka, K. L., & Wheelock, S. J. (2009). New evidence for a magmatic influence on the origin of Valles Marineris, Mars. Journal of Volcanology and Geothermal Research, 185(1-2), 12-27.More infoAbstract: In this paper, we show that the complex geological evolution of Valles Marineris, Mars, has been highly influenced by the manifestation of magmatism (e.g., possible plume activity). This is based on a diversity of evidence, reported here, for the central part, Melas Chasma, and nearby regions, including uplift, loss of huge volumes of material, flexure, volcanism, and possible hydrothermal and endogenic-induced outflow channel activity. Observations include: (1) the identification of a new > 50 km-diameter caldera/vent-like feature on the southwest flank of Melas, which is spatially associated with a previously identified center of tectonic activity using Viking data; (2) a prominent topographic rise at the central part of Valles Marineris, which includes Melas Chasma, interpreted to mark an uplift, consistent with faults that are radial and concentric about it; (3) HiRISE-identified landforms along the floor of the southeast part of Melas Chasma that are interpreted to reveal a volcanic field; (4) CRISM identification of sulfate-rich outcrops, which could be indicative of hydrothermal deposits; (5) GRS K/Th signature interpreted as water-magma interactions and/or variations in rock composition; and (6) geophysical evidence that may indicate partial compensation of the canyon and/or higher density intrusives beneath it. Long-term magma, tectonic, and water interactions (Late Noachian into the Amazonian), albeit intermittent, point to an elevated life potential, and thus Valles Marineris is considered a prime target for future life detection missions. © 2008 Elsevier B.V.
- Komatsu, G., Arzhannikov, S. G., Gillespie, A. R., Burke, R. M., Miyamoto, H., & Baker, V. R. (2009). Quaternary paleolake formation and cataclysmic flooding along the upper Yenisei River. Geomorphology, 104(3-4), 143-164.More infoAbstract: A suite of geomorphological and sedimentological features in the catchment of the upper Yenisei River in the Sayan mountains of southern Siberia testifies to the occurrence of cataclysmic floods that flowed down the river. Evidence of large-scale high-energy flood events includes: 1) gravel dunes, up to a few meters high and spaced 50 to 80 m apart, in the Kyzyl Basin 2) landforms such as hanging valleys and paleochannels and 3) flood sediments in a tributary valley. The origins of the Yenisei floods were likely diverse due to complex hydrological processes operating in the Sayan mountains. The possibilities include failures of multiple, variably impounded (ice, sedimentary, tectonic scarp, and lava flow dams) paleolakes in the two large intermontane basins of Darkhadyn Khotgor and Todza, and other minor basins, in the upper Yenisei River catchment. Dating techniques applied to the paleolakes in the Darkhadyn Khotgor and Todza basins revealed their formation during various periods in the middle-late Pleistocene and Holocene. Flooding from the Darkhadyn Khotgor appears to explain many of the inferred flood features, although contributions by flooding from other paleolake basins cannot be ruled out. Computer simulation of the flooding caused by a Darkhadyn Khotgor paleolake ice-dam failure indicates a probable peak discharge of ∼ 3.5 × 106 m3 s- 1, approximately one-fifth that of the floods that formed the Channeled Scabland in the U.S.A. Many of the outburst events probably occurred in the late Quaternary, but earlier floods could also have occurred. © 2008 Elsevier B.V. All rights reserved.
- Baker, V. R. (2008). Greatest Floods and Largest Rivers. Large Rivers: Geomorphology and Management, 65-74.
- Baker, V. R. (2008). Paleoflood hydrology: Origin, progress, prospects. Geomorphology, 101(1-2), 1-13.More infoAbstract: From an origin in diverse studies of flood geomorphology and Quaternary geology, paleoflood hydrology emerged as a geophysical and an applied hydrological science during the 1970s and 1980s. Since acquiring its formal name in 1982, the most productive approach in paleoflood hydrology has become energy-based inverse hydraulic modeling of discrete paleoflood events, recorded in appropriate settings as slackwater deposits and other paleostage indicators (SWD-PSI), or as various threshold indicators of non-exceedence. Technological advances, particularly in hydraulic modeling and geochronology, were instrumental in moving the discipline to its present status. The most recent advances include (1) new techniques for the accurate geochronology of flood sediments, notably TAMS radiocarbon analyses and OSL dating, and (2) the phenomenal increase in computer power that allows complex hydraulic calculations to become feasible for routine studies. From its initial demonstration in the southwestern United States, SWD-PSI paleoflood hydrology proved its widespread applicability to various landscape environments. Particularly important studies have been accomplished in Australia, China, India, Israel, South Africa, Spain, and Thailand. Paleoflood hydrology has also generated its share of controversy, in part because of the differing viewpoints and attitudes of the two scientific traditions from which it emerged: Quaternary geology/geomorphology versus applied hydrologic/hydraulic engineering. Nevertheless, the future growth of the discipline is assured, given the rapid pace of discoveries that it engenders. Indeed, so many international studies exist that it is appropriate to pursue global syntheses to address interesting and timely questions of extreme flood phenomena in relation to global climatic change. © 2008 Elsevier B.V. All rights reserved.
- Baker, V. R. (2008). Planetary landscape systems: A limitless frontier. Earth Surface Processes and Landforms, 33(9), 1341-1353.More infoAbstract: If it is to be a complete science of landforms and landscapes, geomorphology is not appropriately limited geographically to the terrestrial portions of Earth's surface. Various systems of landforms and their generative processes are best understood in a full planetary context. Moreover, by extending its purview to include the nature of landscapes on Earth-like planets, geomorphological inquiry is not appropriately limited in its philosophical presumptions to the reductionist views that have so successfully guided much of physics. Holistic thinking, exemplified by some aspects of evolutionary biology, and a systems framework may prove to be particularly fruitful for understanding future extraterrestrial discoveries and the general nature of landforms and landscapes. Copyright © 2008 John Wiley & Sons, Ltd.
- Baker, V. R. (2008). The Spokane Flood debates: Historical background and philosophical perspective. Geological Society Special Publication, 301, 33-50.More infoAbstract: The 1920s-1930s debates over the origin of the 'Channeled Scabland' landscape of eastern Washington, northwestern USA, focused on the cataclysmic flooding hypothesis of J Harlen Bretz. During the summer of 1922, Bretz began leading field parties of advanced University of Chicago students into the region. In his first paper, published in the Bulletin of the Geological Society of America, Bretz took special care not to mention cataclysmic origins. However, in a subsequent paper in the Journal of Geology, to the editorial board of which he had recently been added, Bretz formally described his hypothesis that an immense late Pleistocene flood, which he named the 'Spokane Flood', had derived from the margins of the nearby Cordilleran Ice Sheet. This cataclysm neatly accounted for numerous interrelated aspects of the Channeled Scabland landscape and nearby regions. Nevertheless, the geological community largely resisted Bretz's hypothesis for decades, despite his enthusiastic and eloquent defence thereof. Resolution of the controversy came gradually, initially through the recognition by J. T. Pardee of a plausible source for the flooding: ice-dammed Pleistocene glacial Lake Missoula in northern Idaho and western Montana. Eventually, by the 1960s, the field evidence for cataclysmic flooding became overwhelming, and physical processes were found to be completely consistent with that evidence. The controversy is of philosophical interest in regard to its documentation of the attitudes of geologists toward hypotheses, which illustrate aspects of geological reasoning that are distinctive in degree from those of other sciences. © 2008 Geological Society of London.
- Banks, M. E., McEwen, A. S., Kargel, J. S., Baker, V. R., Strom, R. G., Mellon, M. T., Gulick, V. C., Keszthelyi, L., Herkenhoff, K. E., Pelletier, J. D., & Jaeger, W. L. (2008). High Resolution Imaging Science Experiment (HiRISE) observations of glacial and periglacial morphologies in the circum-Argyre Planitia highlands, Mars. Journal of Geophysical Research E: Planets, 113(12).More infoAbstract: The landscape of the Argyre Planitia and adjoining Charitum and Nereidum Montes in the southern hemisphere of Mars has been heavily modified since formation of the Argyre impact basin. This study examines morphologies in the Argyre region revealed in images acquired by the High Resolution Imaging Science Experiment (HiRISE) camera and discusses the implications for glacial and periglacial processes. Distinctive features such as large grooves, semicircular embayments in high topography, and streamlined hills are interpreted as glacially eroded grooves, cirques, and whalebacks or roche moutonnée, respectively. Large boulders scattered across the floor of a valley may be ground moraine deposited by ice ablation. Glacial interpretations are supported by the association of these features with other landforms typical of glaciated landscapes such as broad valleys with parabolic cross sections and stepped longitudinal profiles, lobate debris aprons interpreted as remnant debris covered glaciers or rock glaciers, and possible hanging valleys. Aligned boulders observed on slopes may also indicate glacial processes such as fluting. Alternatively, boulders aligned on slopes and organized in clumps and polygonal patterns on flatter surfaces may indicate periglacial processes, perhaps postglaciation, that form patterned ground. At least portions of the Argyre region appear to have been modified by processes of ice accumulation, glacial flow, erosion, sediment deposition, ice stagnation and ablation, and perhaps subsequent periglacial processes. The type of bedrock erosion apparent in images suggests that glaciers were, at times, wet based. The number of superposed craters is consistent with geologically recent glacial activity, but may be due to subsequent modification. Copyright 2008 by the American Geophysical Union.
- Dohm, J. M., Anderson, R. C., Barlow, N. G., Miyamoto, H., Davies, A. G., Taylor, G. J., Baker, V. R., Boynton, W. V., Keller, J., Kerry, K., Janes, D., Fairén, A. G., Schulze-Makuch, D., Glamoclija, M., Marinangeli, L., Ori, G. G., Strom, R. G., Williams, J., Ferris, J. C., , Rodríguez, J., et al. (2008). Recent geological and hydrological activity on Mars: The Tharsis/Elysium corridor. Planetary and Space Science, 56(7), 985-1013.More infoAbstract: The paradigm of an ancient warm, wet, and dynamically active Mars, which transitioned into a cold, dry, and internally dead planet, has persisted up until recently despite published Viking-based geologic maps that indicate geologic and hydrologic activity extending into the Late Amazonian epoch. This paradigm is shifting to a water-enriched planet, which may still exhibit internal activity, based on a collection of geologic, hydrologic, topographic, chemical, and elemental evidences obtained by the Viking, Mars Global Surveyor (MGS), Mars Odyssey (MO), Mars Exploration Rovers (MER), and Mars Express (MEx) missions. The evidence includes: (1) stratigraphically young rock materials such as pristine lava flows with few, if any, superposed impact craters; (2) tectonic features that cut stratigraphically young materials; (3) features with possible aqueous origin such as structurally controlled channels that dissect stratigraphically young materials and anastomosing-patterned slope streaks on hillslopes; (4) spatially varying elemental abundances for such elements as hydrogen (H) and chlorine (Cl) recorded in rock materials up to 0.33 m depth; and (5) regions of elevated atmospheric methane. This evidence is pronounced in parts of Tharsis, Elysium, and the region that straddles the two volcanic provinces, collectively referred to here as the Tharsis/Elysium corridor. Based in part on field investigations of Solfatara Crater, Italy, recommended as a suitable terrestrial analog, the Tharsis/Elysium corridor should be considered a prime target for Mars Reconnaissance Orbiter (MRO) investigations and future science-driven exploration to investigate whether Mars is internally and hydrologically active at the present time, and whether the persistence of this activity has resulted in biologic activity. © 2008 Elsevier Ltd. All rights reserved.
- Baker, V. R. (2007). Flood hazard science, policy, and values: A pragmatist stance. Technology in Society, 29(2), 161-168.More infoAbstract: The New Orleans hurricane disaster of August 2005 amply illustrates the long-standing failure of relating science to effective policies for reducing flood losses. Particularly flawed is the myth that science constitutes a repository of authoritative knowledge that will objectively serve as the basis for effective policies. This flaw derives from presumptions about the nature of science that can be corrected by employing a pragmatic perspective. Science is the continuing search for truth by a dedicated community of practitioners. Its intrinsic fallibilism means it cannot authoritatively justify a particular action. Instead, its continuous activity provides a reliable guide to action. © 2007 Elsevier Ltd. All rights reserved.
- Baker, V. R. (2007). Introduction. tThe Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement, xix-xxiii.
- Baker, V. R. (2007). Planetary science: Water cycling on Mars. Nature, 446(7132), 150-151.More infoPMID: 17344842;Abstract: The Meridiani Planum region on Mars is rich in minerals derived from evaporation, but lacks a topography consistent with standing water. Do the deposits stem from upwelling groundwater early in the planet's history? ©2007 Nature Publishing Group.
- Baker, V. R., Maruyama, S., & Dohm, J. M. (2007). Tharsis superplume and the geological evolution of early Mars. Superplumes: Beyond Plate Tectonics, 507-522.More infoAbstract: Anomalous aspects of Martian geology are explained by a theory that incorporates the onset and termination of a core dynamo, associated with an early regime of plate tectonics during the first few hundred million years of the planet's history. Rapid accretion of thickened continental crust, as modified by concurrent high impacting rates, volcanism, and denudation, ultimately resulted in the southern highlands. Following cessation of the dynamo, the platetectonic regime terminated with zones of focused subduction in the Tharsis and Elysium areas. The resulting high concentration of water and other volatiles in the Martian deep mantle led to the Tharsis and Elysium superplumes, the long-term persistence of which is responsible for much of the volcanism, tectonism, water outbursts, and climate change that mark the subsequent, 4-billion-year geological history of Mars. © 2007 Springer.
- Coleman, N. M., Dinwidde, C. L., & Baker, V. R. (2007). Evidence that floodwaters filled and overflowed Capri Chasma, Mars. Geophysical Research Letters, 34(7).More infoAbstract: Erosional features on a plateau in the Valles Marineris provide evidence that a lake filled Capri Chasma until it overflowed its eastern rim, carving two large spillover channels. The floodwaters surged into the adjacent lowlands of ancestral Ganges Chasma and eastern Eos Chasma. The channel floor elevation and depth of incision at Daga Vallis reveal that a 1200-m-deep lake water column was drained by the flooding. The width, depth, and steep energy slope (∼0.02) of Daga Vallis and the existence of several cataracts, including a 500-m-high dry falls, demonstrate the power of the floodwaters. We estimate a possible peak discharge rate of 1-6 × 108 M3·s-1. The catastrophic flows may have been triggered by the collapse of topographic barriers in eastern Coprates Chasma, providing a gateway for lake waters in the central Valles Marineris to pour eastward toward Capri Chasma and the lowlands beyond. These may have been among the earliest flows in Simud-Tiu Valles, contributing discharge to a possible sea in the northern plains of Mars. Copyright 2007 by the American Geophysical Union.
- Dohm, J. M., Baker, V. R., Maruyama, S., & Anderson, R. C. (2007). Traits and evolution of the tharsis superplume, Mars. Superplumes: Beyond Plate Tectonics, 523-536.More infoAbstract: When compared to the previous explanations that attempt to explain the long-lived internal heat engine of Tharsis, Mars (e.g., >3 Ga), the Tharsis Superplume hypothesis provides a cohesive explanation for the evolution of the magmatic complex and forms a sound basis for further productive inquiry. Contributors to its formation and long-term, pulsating evolution may include: (1) extremely ancient plate tectonism (Baker et al., this volume), (2) an extremely ancient giant impact in the Arabia Terra region, which is located nearly antipodal to the superplume (Dohm et al., 2004), and (3) later smaller impacts (e.g., Hellas and Isidis) when compared to the putative Arabia impact with a primary basin estimated to be at least 3000 km in diameter. The extensive geological and paleohydrological records of the Tharsis Superplume presented here, which includes extremely long-lived magma and liquid and frozen water interactions in the subsurface and the surface, have tremendous implications concerning future missions to Mars that will unfold the potential astrobiological information that awaits discovery. © 2007 Springer.
- Dohm, J. M., Barlow, N. G., Anderson, R. C., Williams, J., Miyamoto, H., Ferris, J. C., Strom, R. G., Taylor, G. J., Fairén, A. G., Baker, V. R., Boynton, W. V., Keller, J. M., Kerry, K., Janes, D., Rodriguez, J. A., & Hare, T. M. (2007). Possible ancient giant basin and related water enrichment in the Arabia Terra province, Mars. Icarus, 190(1), 74-92.More infoAbstract: A circular albedo feature in the Arabia Terra province was first hypothesized as an ancient impact basin using Viking-era information. To test this unpublished hypothesis, we have analyzed the Viking era-information together with layers of new data derived from the Mars Global Surveyor (MGS) and Mars Odyssey (MO) missions. Our analysis indicates that Arabia Terra is an ancient geologic province of Mars with many distinct characteristics, including predominantly Noachian materials, a unique part of the highland-lowland boundary, a prominent paleotectonic history, the largest region of fretted terrain on the planet, outflow channels with no obvious origins, extensive exposures of eroded layered sedimentary deposits, and notable structural, albedo, thermal inertia, gravity, magnetic, and elemental signatures. The province also is marked by special impact crater morphologies, which suggest a persistent volatile-rich substrate. No one characteristic provides definitive answers to the dominant event(s) that shaped this unique province. Collectively the characteristics reported here support the following hypothesized sequence of events in Arabia Terra: (1) an enormous basin, possibly of impact origin, formed early in martian history when the magnetic dynamo was active and the lithosphere was relatively thin, (2) sediments and other materials were deposited in the basin during high erosion rates while maintaining isostatic equilibrium, (3) sediments became water enriched during the Noachian Period, and (4) basin materials were uplifted in response to the growth of the Tharsis Bulge, resulting in differential erosion exposing ancient stratigraphic sequences. Parts of the ancient basin remain water-enriched to the present day. © 2007 Elsevier Inc. All rights reserved.
- Keller, J. M., Boynton, W. V., Karunatillake, S., Baker, V. R., Dohm, J. M., Evans, L. G., Finch, M. J., Hahn, B. C., Hamara, D. K., Janes, D. M., Kerry, K. E., Newsom, H. E., Reedy, R. C., Sprague, A. L., Squyres, S. W., Starr, R. D., Taylor, G. J., & Williams, R. M. (2007). Equatorial and midlatitude distribution of chlorine measured by Mars Odyssey GRS. Journal of Geophysical Research E: Planets, 112(3).More infoAbstract: The 2001 Mars Odyssey Gamma Ray Spectrometer (GRS) has made the first measurement of the equatorial and midlatitude distribution of C1 at the near-surface of Mars. A mean concentration value of 0.49 wt% C1 has been determined from a grand sum of GRS spectra collected over the planet excluding high-latitude regions. C1 is significantly enriched within the upper few tens of centimeters of the surface relative to the Martian meteorites and estimates for the bulk composition of the planet. However, C1 is not homogeneously distributed and varies by a factor of ∼4 even after smoothing of data with a 10°-arc-radius filter. Several contiguous, geographically large (>20°) regions of high and low C1 concentrations are present. In particular, a region centered over the Medusae Fossae Formation west of Tharsis shows significantly elevated C1. A large region north of Syrtis Major extending into Utopia Planitia in the northern hemisphere shows the lowest C1 concentrations. On the basis of hierarchical multivariate correlations, C1 is positively associated with H while negatively associated with Si and thermal inertia. We discuss four possible geologic mechanisms (aeolian, volcanic, aqueous, and hydrothermal) that may have affected the C1 distribution seen by GRS. While some of the distribution may be due to C1-rich dust deposits transported by aeolian processes, this mechanism does not appear to account for all of the observed variability. We propose that reactions with volcanic exhalations may have been important for enriching C1 in Medusae Fossae Formation material. Copyright 2006 by the American Geophysical Union.
- Mahaney, W. C., Miyamoto, H., Dohm, J. M., Baker, V. R., Cabrol, N. A., Grin, E. A., & Berman, D. C. (2007). Rock glaciers on Mars: Earth-based clues to Mars' recent paleoclimatic history. Planetary and Space Science, 55(1-2), 181-192.More infoAbstract: The Mars Orbital Camera onboard the Mars Global Surveyor spacecraft, which is currently orbiting about Mars, has revealed hundreds of pristine lobate and tongue-shaped flows that closely display the morphological characteristics of terrestrial rock glaciers, both tongue- and lobe-shaped forms. Generally located between 30°S and 47°S latitude on Mars, these terrestrial-like flows have important paleoenvironmental implications, including marking environmental change from current, present cold and dry desert martian conditions to cold wetter climates in the past. Paleoenvironmental conditions, hypothesized to have significantly influenced the dimensions of the terrestrial-like flows, is supported through a simple dynamic model with the power-law rheology. The presence of periglacial landforms on Mars indicates the possible presence of permafrost and potential caches of water for future exobiological exploration. © 2006 Elsevier Ltd. All rights reserved.
- Miyamoto, H., Komatsu, G., Baker, V. R., Dohm, J. M., Ito, K., & Tosaka, H. (2007). Cataclysmic Scabland flooding: Insights from a simple depth-averaged numerical model. Environmental Modelling and Software, 22(10), 1400-1408.More infoAbstract: This work presents numerical assessments of possible routing paths for the reported late Pleistocene Missoula floods, which involved Earth's largest known peak discharges of freshwater. For our numerical model, we adopt the diffusion wave approximation of the shallow-water equation with the empirical Manning coefficient. This simplification is required because (1) most previous studies are one-dimensional or analytical studies based on simple equations, so that our two-dimensional expansion is a natural step towards more sophisticated models; (2) a simple model can easily incorporate the effect of complicated topography; and (3) lower computational costs permit a broader exploration of parameters. Important and new insights obtained from this work include: (1) numerically, we confirm the presence of the Cordilleran Ice Sheet at the time of the Missoula floods; (2) floods with relatively small peak discharges cannot inundate some major reaches, including the Cheney Palouse Scabland Tract; (3) deposits indicative of multiple floods are mostly confined in the locations that can be inundated by relatively lower peak flood discharges; and (4) although Lake Missoula glacial lake failure scenario can reasonably reproduce extensive water coverage, the best fit result to the geological evidence of flooding is obtained when the total water volume is three times larger than that estimated for Glacial Lake Missoula. The above results do not negate previous works, but indicate the need for further detailed field investigation and more sophisticated modeling in order to pursue further understanding of the complex behavior of megaflooding in the Channeled Scabland. © 2006 Elsevier Ltd. All rights reserved.
- Taylor, G. J., Boynton, W. V., Brückner, J., Wänke, H., Dreibus, G., Kerry, K. E., Keller, J. M., Reedy, R. C., Evans, L. G., Starr, R. D., Squyres, S. W., Karunatillake, S., Gasnault, O., Maurice, S., d'Uston, C., Englert, P., Dohm, J. M., Baker, V., Hamara, D., , Janes, D. M., et al. (2007). Bulk composition and early differentiation of Mars. Journal of Geophysical Research E: Planets, 112(3).More infoAbstract: We report the concentrations of K, Th, and Fe on the Martian surface, as determined by the gamma ray spectrometer onboard the 2001 Mars Odyssey spacecraft. K and Th are not uniformly distributed on Mars. K ranges from 2000 to 6000 ppm; Th ranges from 0.2 to 1 ppm. The K/Th ratio varies from 3000 to 9000, but over 95% of the surface has K/Th between 4000 and 7000. Concentrations of K and Th are generally higher than those in basaltic Martian meteorites (K = 200-2600 ppm; Th = 0.1-0.7 ppm), indicating that Martian meteorites are not representative of the bulk crust. The average K/Th in the crust is 5300, consistent with the Wänke-Dreibus model composition for bulk silicate Mars. Fe concentrations support the idea that bulk Mars is enriched in FeO compared to Earth. The differences in K/Th and FeO between Earth and Mars are consistent with the planets accreting from narrow feeding zones. The concentration of Th on Mars does not vary as much as it does on the Moon (where it ranges from 0.1 to 12 ppm), suggesting that the primary differentiation of Mars differed 'from that of the Moon. If the average Th concentration (0.6 ppm) of the surface is equal to the average of the entire crust, the crust cannot be thicker than about 118 km. If the crust is about 57 km thick, as suggested by geophysical studies, then about half the Th is concentrated in the crust. Copyright 2006 by the American Geophysical Union.
- Taylor, G. J., Stopar, J. D., Boynton, W. V., Karunatillake, S., Keller, J. M., Brückner, J., Wänke, H., Dreibus, G., Kerry, K. E., Reedy, R. C., Evans, L. G., Starr, R. D., Martel, L. M., Squyres, S. W., Gasnault, O., Maurice, S., d'Uston, C., Englert, P., Dohm, J. M., , Baker, V. R., et al. (2007). Variations in K/Th on Mars. Journal of Geophysical Research E: Planets, 112(3).More infoAbstract: K/Th determined by the Mars Odyssey Gamma Ray Spectrometer varies by a factor of 3 on Mars (3000 to 9000), but over 95% of the surface area has K/Th between 4000 and 7000. K/Th is distinctly lower than average in some areas, including west of Olympus Mons in the Amazonis Planitia, the region around Memnonia Fossae, Chryse Planitia, southeastern Arabia Terra, Syrtis Major Planum, and northwest of Apollinaris Patera. On the other hand, K/Th is distinctly higher than average in other areas, including the central part of Valles Marineris and the surrounding highlands, and in the northern part of Hellas. The generally modest variation in K/Th may be explained by inherent variations in igneous rocks and by variations in the extent of aqueous alteration. Copyright 2006 by the American Geophysical Union.
- Alexis, J., Kargel, J., Crown, D. A., F., L., Tanaka, K. L., Baker, V., Miyamoto, H., Dohm, J. M., Sasaki, S., & Komatsu, G. (2006). Headward growth of chasmata by volatile outbursts, collapse, and drainage: Evidence from ganges chaos, Mars. Geophysical Research Letters, 33(18).More infoAbstract: The nature and significance of collapse processes in Capri, Eos, and Ganges Chasmata remain poorly understood. Using Ganges Chasma as a type locality, these chasmata are interpreted to be the result of clustering and assimilation of multiple chaotic terrains, which primarily formed by localized depressurization-induced or thermally-triggered dissociation of buried gas clathrate hydrates and explosive eruption of gas-saturated ground water. Such crustal destabilization could have been triggered by (1) deep fracture propagation from the Martian surface, (2) magmatic intrusions and associated heating and inflation-induced terrain fracturing, and/or (3) climatic thaw and thinning/weakening of the permafrost over the clathrate and gas-rich groundwater zones. Volume increases associated with release of gases contributed to the xpulsion of groundwater and fluidized sediments at the surface, thereby carving the higher outflow channels peripheral to the chasmata and the lower outflow channel floors of the chasmata and outflow channels. Copyright 2006 by the American Geophysical Union.
- Baker, V. R. (2006). Geomorphological evidence for water on Mars. Elements, 2(3), 139-143.More infoAbstract: Martian landscapes and landforms indicate episodic activity by water and ice, extending from the planet's earliest history up to the present day. Most of the relevant fluvial, glacial, volcano-ice, periglacial, lacustrine (even "marine"), and related landforms have direct counterparts on Earth. Moreover, they exist in causally related, holistic associations of space and time that confirm their relationship to a long-term history of water-related activity. Although strong geomorphological evidence for many of these relationships has been apparent for 30 years, its scientific importance has only been recently appreciated because of direct geochemical measurements of water and ice features by surface robotic and orbital instruments.
- Baker, V. R. (2006). Palaeoflood hydrology in a global context. Catena, 66(1-2), 161-168.More infoAbstract: From its origins as a geological study of flood erosion and sediments the science palaeoflood hydrology matured to become an indispensable means for understanding the hydrology of very large, rare floods. Such floods are increasingly posing risks to human habitation. More that 3 decades of research in palaeoflood hydrology produced spectacular advances in capabilities for (1) accurately determining palaeoflood ages, (2) quantifying the magnitudes and dynamics of palaeoflood processes, and (3) incorporating palaeoflood data into various modeling procedures for risk assessments. Palaeoflood studies now have a global sweep, and it is appropriate to apply the information they provide to address questions of global environmental change. In doing so, it will be necessary to reconsider aspects of science-society interactions because of the many failings of these in current practice. © 2005 Elsevier B.V. All rights reserved.
- Baker, V. R. (2006). Water and the evolutionary geological history of Mars. Bollettino della Societa Geologica Italiana, 125(3), 357-369.More infoAbstract: Mars and Earth are the only two planets known to have long histories of dynamical cycling of water through their atmosphere, lithosphere, and cryosphere. Although we have known for thirty years that Mars had an early history with aqueous activity on its surface, exciting new results from current Mars missions are only now revealing the extensive sedimentary evidence of that history. Early Mars had extensive lakes and probably transient seas that were associated with a climate capable of generating the precipitation and runoff to sculpt its landscape and fill sedimentary basins. Well-preserved fluvial deltas show that early Mars was surprisingly Earthlike in its geological processes. The immense quantity of water implied for sequestering in the Martian permafrost (as ground ice) and beneath it (as ground water) requires an explanation as to the history of water recycling. These and other anomalous aspects of Martian geology are explained by a theory that incorporates the onset and termination of a core dynamo, associated with an early regime of plate tectonics during the first few hundred million years of the planet's history. Rapid accretion of thickened continental crust, as modified by concurrent high impacting rates, volcanism, and denudation, ultimately resulted in the southern highlands. Following cessation of the dynamo, the plate-tectonic regime terminated with zones of focused subduction in the Tharsis and Elysium areas. The resulting high concentration of water and other volatiles in the Martian deep mantle led to the Tharsis and Elysium superplumes, the long-term persistence of which is responsible for much of the volcanism, tectonism, water outbursts, and climate change that mark the subsequent, 4 billion year geological history of Mars.
- Chien, S., Cichy, B., Davies, A., Tran, D., Rabideau, G., Castano, R., Sherwood, R., Nghiem, S., Greeley, R., Doggett, T., Baker, V., Dohm, J., Felipe, I. p., Mandl, D., Frye, S., Shulman, S., Ungar, S., Brakke, T., Ong, L., , Descloitres, J., et al. (2006). An autonomous earth observing sensorweb. Proceedings - IEEE International Conference on Sensor Networks, Ubiquitous, and Trustworthy Computing, 2006 II, 178-185.More infoAbstract: We describe a network of sensors linked by software and the internet to an autonomous satellite observation response capability. This sensor network is designed with a flexible, modular, architecture to facilitate expansion in sensors, customization of trigger conditions, and customization of responses. This system has been used to implement a global surveillance program of multiple science phenomena including: volcanoes, flooding, cryosphere events, and atmospheric phenomena. In this paper we describe the importance of the Earth observing sensorweb application as well as overall architecture for the network © 2006 IEEE.
- Davies, A. G., Chien, S., Baker, V., Doggett, T., Dohm, J., Greeley, R., Ip, F., ̌o, R. C., Cichy, B., Rabideau, G., Tran, D., & Sherwood, R. (2006). Monitoring active volcanism with the Autonomous Sciencecraft Experiment on EO-1. Remote Sensing of Environment, 101(4), 427-446.More infoAbstract: The ability to monitor and rapidly react to remote detection of volcanic activity has been greatly improved through use of the Autonomous Sciencecraft Experiment (ASE), an advanced software application installed on a spacecraft in Earth orbit. ASE is a NASA New Millennium Program experiment demonstrating science-driven autonomous command and control of a spacecraft. Flying on the Earth Observing-1 (EO-1) spacecraft, ASE successfully detected thermal emission from the Mt. Erebus lava lake on 7 May 2004, having analyzed a Hyperion hyperspectral data product on board the spacecraft. EO-1 was re-tasked by ASE to obtain a follow-up observation 7 h later and sent a notification of detection of volcanic activity to the ground. The entire process was carried out autonomously. Initial acquisition to receipt on the ground of the positive detection took less than 3 h, a process that without ASE would have taken weeks. The ASE Thermal Classifier has detected several styles of effusive volcanic activity: active lava lakes, pahoehoe flow fields, open channel flows and lava domes. ASE successfully demonstrated that science-driven spacecraft operation greatly enhances science return per returned byte through the identification of the most valuable data, allowing prioritization of downlink products and the discarding of null data sets. This technology has applications on missions elsewhere in the solar system. Modified thermal classifiers can be used for detecting and monitoring active volcanism on the jovian satellite Io, the neptunian moon Triton, and searching for active volcanism on Mars and icy satellites. The success of ASE is an incentive for future instrument and mission designers to consider on-board data-processing requirements (especially data storage capacity, number of processors and processor speed, and RAM) in order to take advantage of this flight-proven technology. © 2005 Elsevier Inc. All rights reserved.
- Doggett, T., Greeley, R., Chien, S., Castano, R., Cichy, B., Davies, A. G., Rabideau, G., Sherwood, R., Tran, D., Baker, V., Dohm, J., & Ip, F. (2006). Autonomous detection of cryospheric change with hyperion on-board Earth Observing-1. Remote Sensing of Environment, 101(4), 447-462.More infoAbstract: On-board detection of cryospheric change in sea ice, lake ice, and snow cover is being conducted as part of the Autonomous Sciencecraft Experiment (ASE), using classifiers developed for the Hyperion hyper-spectral visible/infrared spectrometer on-board the Earth Observing-1 (EO-1) spacecraft. This classifier development was done with consideration for the novel limitations of on-board processing, data calibration, spacecraft targeting error and the spectral range of the instrument. During on-board tests, these algorithms were used to measure the extent of cloud, snow, and ice cover at a global suite of targets. Coupled with baseline imaging, uploaded thresholds were used to detect cryospheric changes such as the freeze and thaw of lake ice and the formation and break-up of sea ice. These thresholds were used to autonomously trigger follow-up observations, demonstrating the capability of the technique for future planetary missions where downlink is a constrained resource and there is high interest in data covering dynamic events, including cryospheric change. Before upload classifier performance was assessed with an overall accuracy of 83.3% as measured against manual labeling of 134 scenes. Performance was further assessed against field mapping conducted at Lake Mendota, Wisconsin as well as with labeling of scenes that were classified during on-board tests. © 2006 Elsevier Inc. All rights reserved.
- Felipe, I. p., Dohm, J. M., Baker, V. R., Brakenridge, R., Davies, A. G., & Chien, S. (2006). Autonomous flood Sensorweb: Multi-sensor rapid response and early flood detection. Proceedings of the iEMSs 3rd Biennial Meeting," Summit on Environmental Modelling and Software".More infoAbstract: Extreme floods have been reported to be more frequent partly due to global warming. As such, the necessity for timely detection and mapping of floods is increasingly important in order to protect lives and livelihoods. Floods affect large regions of the Earth and cannot be reliably predicted. Hydrological data from in-situ sensors are sparse and cannot map the full extent of flooding. The use of satellite-based information for assessing floods is not new. However, the problem with satellite remote sensing historically has been both the large areas affected and obtaining timely ground-based reception of satellite data. The Autonomous Sciencecraft Experiment (ASE) experiment overcomes the data size and downlink problems. For flood processes, the ASE includes a satellite-based floodwater classification algorithm (ASE-FLOOD), which reliably detects flooding as it occurs and autonomously triggers further image acquisition to map and track flood changes through time. In addition, the ASE enables more effective and timely monitoring for other dynamic transient events on Earth, which include volcanic eruptions and sea ice breakups. The Flood Sensorweb is an extension of ASE and serves to link different remote sensing assets obtained at different spatial and temporal resolutions for flood detection and monitoring. It is a demonstration in which Dartmouth Flood Observatory's Water Surface Watch (a satellite-based global runoff monitoring system) alerts ASE operations of sites where there is potential flooding. Based on these alerts, ASE autonomously retargets NASA's EO-1 spacecraft to verify flooding conditions at these sites, thereafter acquiring local high-resolution images of these flooded areas. The Flood Sensorweb offers an important asset for the study of transient hydrological phenomena globally, especially at remote locations. The use of autonomous change detection, triggering the needed local high-resolution imaging by automatic systems, provides the critical near real-time data needed for early detection and modeling of seasonal and extreme floods.
- Felipe, I. p., Dohm, J. M., Baker, V. R., Doggett, T., Davies, A. G., Castaño, R., Chien, S., Cichy, B., Greeley, R., Sherwood, R., Tran, D., & Rabideau, G. (2006). Flood detection and monitoring with the Autonomous Sciencecraft Experiment onboard EO-1. Remote Sensing of Environment, 101(4), 463-481.More infoAbstract: In this paper, we present a new way of detecting and monitoring flooding through the Autonomous Sciencecraft Experiment (ASE) [Chien, S. T., Debban, C., Yen, R., Sherwood, R. Castano, B., & Cichy, A. G. et al. (2001). ASC Science Study Report, available from http://ASE.jpl.nasa.gov], which is part of the Space Technology 6 effort under NASA's New Millennium Program. Recent autonomy experiments conducted on Earth Observing 1 (EO-1) using the ASE flight software have demonstrated the ability of several science algorithms to successfully classify key features including flood-induced changes, in hyperspectral images captured by the EO-1 Hyperion instrument. Furthermore, onboard science analysis on the classified images has been performed, and then used to modify an operational plan without interaction from the ground (Sherwood, R., Chien, S., Tran, D., Cichy, B., Castano, R., Davies, A., et al. (2004). Preliminary results of the autonomous sciencecraft experiment. In: Proceedings of the IEEE Aerospace Conference, Big Sky, MT). These algorithms are used to downlink science data only when change occurs, and to detect features of scientific interests such as flooding, volcanic eruptions, and the formation and breakup of sea ice. The purpose of this paper is to demonstrate the success of ASE and its implications on detecting, mapping, and monitoring transient processes such as flooding autonomously from space. Mapping of water inundation and its change through time is part of our focus in studying transient processes from space. In 2004, hyperspectral data were acquired from the Hyperion instrument for target areas around the world that have a high potential for flooding to develop and test floodwater classifiers. In addition, classifier thresholds were determined from both normal flows and possible flood conditions. The paper introduces the development, testing, and success of the ASE software in detecting and reacting to flooding in near real-time. ASE is now operational and flight-tested, and, thus, ready to use for space-borne reconnaissance. Successful demonstration of the floodwater classifiers includes the capture of a rare flooding event of the Australian Diamantina River during ground testing in February 2004, and the detection of flood-related changes along the Brahmaputra River in Bangladesh and the Yukon River in Alaska during onboard testing on EO-1 in 2005. Both of these detections led to triggered responses onboard the spacecraft, which included acquiring additional Hyperion scenes. These results pave the way for future smart reconnaissance missions of transient processes on Earth and beyond. It is hoped that ASE will become a default in future missions to increase the science return by introducing spacecraft autonomy for detection and monitoring of science events, which otherwise would be discovered too late or altogether missed. © 2006 Elsevier Inc. All rights reserved.
- Kale, V. S., & Baker, V. R. (2006). An extraordinary period of low-magnitude floods coinciding with the Little Ice Age: Palaeoflood evidence from central and western India. Journal of the Geological Society of India, 68(3), 477-483.More infoAbstract: Fluvial archives include slackwater flood deposits (SWD), which not only preserve information about centennial- to millennial-scale changes in the flood regime conditions, but also provide information on climate variability and extreme climatic events. The present study is based on SWD evidence from six large rivers in central and western India. A remarkable feature that has emerged from the palaeoflood analyses is that the evidence of large floods between circa 14th and 19th century AD is generally missing. Considering the manner in which the rivers build the palaeoflood sequences in stable bedrock gorges, the striking and conspicuous absence of flood deposits of this period indicates a significantly reduced frequency of large floods. Since modern floods on these rivers are the result of severe cyclonic storms, the absence of large palaeofloods not only implies a sharp decline in the frequency of flood-producing severe cyclonic systems, but also an overall decrease in the summer monsoon intensity. Interestingly, this period of less frequent large floods (ca. 14th-19th century AD) approximately coincides with the Little Ice Age (1300 to 1850 AD), which was characterized by relatively cool and dry conditions, and a weakening of the Indian summer monsoon. © Geol. Soc. India.
- Miyamoto, H., Itoh, K., Komatsu, G., Baker, V. R., Dohm, J. M., Tosaka, H., & Sasaki, S. (2006). Numerical simulations of large-scale cataclysmic floodwater: A simple depth-averaged model and an illustrative application. Geomorphology, 76(1-2), 179-192.More infoAbstract: A simple numerical simulation code is developed to quantitatively discuss the behaviors of past cataclysmic floods, whose rigorous hydraulic descriptions would be too complex to be supported by typically available field data. The code aims to keep the basic equations simple and the required computational costs low, which allows greater exploration of parameter space. Examination of both the qualitative meaning of turbulent equations and the relative importance of terms in the shallow water equation have resulted in the adoption of the depth-averaged diffusion wave approximation in two dimensions, as well as Manning's empirical equation for simplification. On the other hand, topography is included as a boundary condition, since topography plays an important role in selecting flood routes. The model provides important advantages over theoretical analyses or one-dimensional simulations, including: (1) the reproduction of complicated water flow paths such as bifurcations and reconvergences; (2) the reconstruction of hydrological relationships among the water paths; and (3) the direct comparison among the calculated extent of the flood inundation (including floodwater depths) and geological and geomorphological observations. Preliminary reconstructions of the Missoula floods demonstrate the advantages of this new approach. The method of coupling field-based flood information with two-dimensional analysis of an entire flow path provides a basis for estimating the peak discharges and flow durations of cataclysmic megafloods on Earth with direct bearing on the understanding of regional paleohydrological histories of Mars. © 2005 Elsevier B.V. All rights reserved.
- Alexis, J., Sasaki, S., Dohm, J. M., Tanaka, K. L., Strom, B., Kargel, J., Kuzmin, R., Miyamoto, H., Spray, J. G., Fairén, A. G., Komatsu, G., Kurita, K., & Baker, V. (2005). Control of impact crater fracture systems on subsurface hydrology, ground subsidence, and collapse, Mars. Journal of Geophysical Research E: Planets, 110(6), 1-22.More infoAbstract: Noachian layered materials are pervasively exposed throughout the highlands of Mars. The layered deposits, in places many kilometers thick, exhibit impact craters of diverse morphologic characteristics, ranging from highly degraded to pristine, most of which formed during the period of heavy bombardment. In addition, exhumed impact craters, ancient channels, and fluvial and alluvial fans are visible in the layered deposits through MOC imagery. These features are more abundant in Noachian terrains, which indicates relatively high erosion rates during ancient Mars that competed with heavy meteoritic bombardment. The Noachian layered materials are thus expected to contain numerous buried impact craters in various states of preservation. Here, we propose that impact craters (buried and exposed) and associated fracture systems dominate the basement structural fabric of the ancient highlands and that they have significantly influenced the hydrogeology. Diversity in the occurrence of high and low densities of impact craters and associated fracture systems controls the magnitude of the local effects of magmatic-driven hydrothermal activity. In and surrounding the Tharsis region, for example, the formation of chaotic terrains (the source regions of the circum-Chryse outflow channel system) and a large diversity of collapse structures, including impact crater moats and pit chains, appear to be the result of enhanced hydrothermal activity. Copyright 2005 by the American Geophysical Union.
- Baker, V. R. (2005). Planetary science: Picturing a recently active Mars. Nature, 434(7031), 280-283.More infoPMID: 15772631;
- Berman, D. C., Hartmann, W. K., Crown, D. A., & Baker, V. R. (2005). The role of arcuate ridges and gullies in the degradation of craters in the Newton Basin region of Mars. Icarus, 178(2), 465-486.More infoAbstract: A survey of craters in the vicinity of Newton Basin, using high-resolution images from Mars Global Surveyor and Mars Odyssey, was conducted to find and analyze examples of gullies and arcuate ridges and assess their implications for impact crater degradation processes. In the Phaethontis Quadrangle (MC-24), we identified 225 craters that contain these features. Of these, 188 had gullies on some portion of their walls, 118 had arcuate ridges at the bases of the crater walls, and 104 contained both features, typically on the same crater wall. A major result is that the pole-facing or equator-facing orientation of these features is latitude dependent. At latitudes >44° S, equator-facing orientations for both ridges and gullies are prevalent, but at latitudes
- Chien, S., Cichy, B., Davies, A., Tran, D., Rabideau, G., Castano, R., Sherwood, R., Nghiem, S., Greeley, R., Doggett, T., Baker, V., Dohm, J., Felipe, I. p., Mandl, D., Frye, S., Shulman, S., Unga, S., Brakke, T., Descloitres, J., , Jones, J., et al. (2005). Autonomous response in an autonomous earth observing sensorweb. European Space Agency, (Special Publication) ESA SP, 325-331.More infoAbstract: We describe a network of sensors linked by software and the internet to an autonomous satellite observation response capability. This system of systems is designed with a flexible, modular, architecture to facilitate expansion in sensors, customization of trigger conditions, and customization of responses. This system has been used to implement a global surveillance program of science phenomena including: volcanoes, flooding, cryosphere events, and atmospheric phenomena. In this paper we describe the importance of the earth observing sensorweb application as well as overall architecture for the system of systems.
- Chien, S., Cichy, B., Davies, A., Tran, D., Rabideau, G., Castano, R., Sherwood, R., Nghiem, S., Greeley, R., Doggett, T., Baker, V., Dohm, J., Felipe, I. p., Mandl, D., Frye, S., Shulman, S., Ungar, S., Brakke, T., Descloitres, J., , Jones, J., et al. (2005). An autonomous earth observing sensorweb. Conference Proceedings - IEEE International Conference on Systems, Man and Cybernetics, 4, 3944-3951.More infoAbstract: We describe a network of sensors linked by software and the internet to an autonomous satellite observation response capability. This system of systems is designed with a flexible, modular, architecture to facilitate expansion in sensors, customization of trigger conditions, and customization of responses. This system has been used to implement a global surveillance program of science phenomena including: volcanoes, flooding, cryosphere events, and atmospheric phenomena. In this paper we describe the importance of the earth observing sensorweb application as well as overall architecture for the system of systems. © 2005 IEEE.
- Fairén, A. G., Dohm, J. M., Uceda, E. R., Rodríguez, A. P., Baker, V. R., Fernández-Remolar, D., Schulze-Makuch, D., & Amils, R. (2005). Prime candidate sites for astrobiological exploration through the hydrogeological history of Mars. Planetary and Space Science, 53(13), 1355-1375.More infoAbstract: The hydrogeological evolution of Mars has been proposed to be dominated by the development of the Tharsis Magmatic Complex through superplume activity, with related magmatic-pulse-driven flood inundations that directly influence the shaping of the northern plains, the evolution of the atmosphere and climate, and subsurface and surface water processes. On the other hand, several possible biological models and terrestrial analogues have been suggested for Mars during the last decade, including the description of putative microfossils and the proposal of sedimentary units. Here we revisit these scenarios and present a possible bridge that integrates the geological, paleohydrological, and the putative biological histories of the planet. We primarily focus on the Noachian, a time period that arguably has recorded an inner dynamo, plate tectonics, and an ocean that may have covered one-third of the total surface area of Mars, due to its implications on the possible origin and early evolution of life. This stage is followed by a long-lived cold and dry phase, briefly punctuated by transient magmatic-driven hydrological cycles, dominated by a stagnant-lid/superplume regime, which directly influences the processes of natural selection on the putative early biosphere. Based on this hypothesized evolution of the planet, we suggest three martian locations as prime candidate sites for astrobiological exploration, each one corresponding to an inundation period: Meridiani Planum (Noachian/Early Hesperian), Mangala Valles (Late Hesperian/Early Amazonian), and Orcus Patera (Amazonian). © 2005 Elsevier Ltd. All rights reserved.
- Anderson, R. C., Dohm, J. M., Haldemann, A. F., Hare, T. M., & Baker, V. R. (2004). Tectonic histories between Alba Patera and Syria Planum, Mars. Icarus, 171(1), 31-38.More infoAbstract: Syria Planum and Alba Patera are two of the most prominent features of magmatic-driven activity identified for the Tharsis region and perhaps for all of Mars. In this study, we have performed a Geographic Information System-based comparative investigation of their tectonic histories using published geologic map information and Mars Orbiter Laser Altimetry (MOLA) data. Our primary objective is to assess their evolutional histories by focusing on their extent of deformation in space and time through stratigraphic, paleotectonic, topographic, and geomorphologic analyses. Though there are similarities among the two prominent features, there are several distinct differences, including timing deformational extent, and tectonic intensity of formation. Whereas Alba Patera displays a major pulse of activity during the Late Hesperian/Early Amazonian, Syria Planum is a long-lived center that displays a more uniform distribution of simple graben densities ranging from the Noachian to the Amazonian, many of which occur at greater distances away from the primary center of activity. The histories of the two features presented here are representative of the complex, long-lived evolutional history of Tharsis. © 2004 Elsevier Inc. All rights reserved.
- Baker, V. R. (2004). Palaeofloods and global change. Journal of the Geological Society of India, 64(4), 395-401.More infoAbstract: A great weakness of various international scientific initiatives in global change, earth-system science, and related hydrological assessment of flood hazards is their overemphasis on prediction from idealized conceptual models. The latter are abstract constructs made possible by rapidly increasing computer power but predicated upon often unverified and sometimes unverifiable assumptions. It is now realized that abrupt climate change and extreme events pose more of a global change hazard than do the mean climate phenomena predicted by global climate models (GCMs). For 20 years there has been an overemphasis on developing these models as the principal tool for dealing with threats to habitability of the planet. In contrast to unverified predictions of the future given by GCMs, palaeoflood data provide evidence of real-work cataclysms that people can understand sufficiently to alter their perceptions of hazards, thereby stimulating appropriate action toward mitigation. This issue is particularly important in the world's tropical monsoon areas, which are prone to especially extreme floods and high variability in their magnitude and frequency. These areas, which are inhabited by half of the Earth's human population, also have excellent sources of palaeoflood information, which comprise a natural archive that can appropriately stimulate productive hazard reduction. © Geol. Soc. India.
- Chien, S., Sherwood, R., Tran, D., Cichy, B., Rabideau, G., Castano, R., Davies, A., Lee, R., Mandl, D., Frye, S., Trout, B., Hengemihle, J., D'Agostino, J., Shulman, S., Ungar, S., Brakke, T., Boyer, D., Gaasbeck, J. V., Greeley, R., , Doggett, T., et al. (2004). The EO-1 Autonomous Science Agent. Proceedings of the Third International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS 2004, 1, 420-427.More infoAbstract: An Autonomous Science Agent is currently flying onboard the Earth Observing One Spacecraft. This software enables the spacecraft to autonomously detect and respond to science events occurring on the Earth. The package includes software systems that perform science data analysis, deliberative planning, and run-time robust execution. Because of the deployment to a remote spacecraft, this Autonomous Science Agent has stringent constraints of autonomy, reliability, and limited computing resources. We describe the constraints and how they were addressed in our agent design, validation, and deployment.
- Chien, S., Sherwood, R., Tran, D., Cichy, B., Rabideau, G., Castano, R., Davies, A., Mandl, D., Frye, S., Trout, B., Hengemihle, J., D'Agostino, J., Shulman, S., Ungar, S., Brakke, T., Boyer, D., Gaasbeck, J. V., Greeley, R., Doggett, T., , Baker, V., et al. (2004). Onboard autonomy on the Earth Observing One mission. Collection of Technical Papers - AIAA 1st Intelligent Systems Technical Conference, 2, 982-989.More infoAbstract: The Earth Observing One Spacecraft is currently flying The Autonomous Sciencecraft Experiment (ASE) - onboard autonomy software to improve science return. The ASE software enables the spacecraft to autonomously detect and respond to science events occurring on the Earth. ASE includes software systems that perform science data analysis, mission planning, and run-time robust execution. In this article we describe the autonomy flight software and how it enables a new paradigm of autonomous science and mission operations. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc.
- Dohm, J. M., Ferris, J. C., Barlow, N. G., Baker, V. R., Mahaney, W. C., Anderson, R. C., & Hare, T. M. (2004). The northwestern slope valleys (NSVs) region, Mars: A prime candidate site for the future exploration of Mars. Planetary and Space Science, 52(1-3), 189-198.More infoAbstract: The northwestern slope valleys region is a prime candidate site for future science-driven Mars exploration because it records Noachian to Amazonian Tharsis development in a region that encapsulates (1) a diverse and temporally extensive stratigraphic record, (2) at least three distinct paleohydrologic regimes, (3) gargantuan structurally controlled flood valleys that generally correspond with gravity and magnetic anomalies, possibly marking ancient magnetized rock materials exposed by fluvial activity, (4) water enrichment, as indicated by Mars Odyssey and impact crater analyses, (5) long-lived magma and ground water/ice interactions that could be favorable for the development and sustenance of life, and (6) potential paleosol development. This region has high probability to yield significant geologic, climatic, and exobiologic information that could revolutionize our understanding of Mars. © 2003 Elsevier Ltd. All rights reserved.
- Fairén, A. G., Fernández-Remolar, D., Dohm, J. M., Baker, V. R., & Amils, R. (2004). Inhibition of carbonate synthesis in acidic oceans on early Mars. Nature, 431(7007), 423-426.More infoPMID: 15386004;Abstract: Several lines of evidence have recently reinforced the hypothesis that an ocean existed on early Mars1-7. Carbonates are accordingly expected to have formed from oceanic sedimentation of carbon dioxide from the ancient martian atmosphere7,8. But spectral imaging of the martian surface has revealed the presence of only a small amount of carbonate, widely distributed in the martian dust9. Here we examine the feasibility of carbonate synthesis in ancient martian oceans using aqueous equilibrium calculations. We show that partial pressures of atmospheric carbon dioxide in the range 0.8-4 bar, in the presence of up to 13.5 mM sulphate and 0.8 mM iron in sea water8, result in an acidic oceanic environment with a pH of less than 6.2. This precludes the formation of siderite, usually expected to be the first major carbonate mineral to precipitate8. We conclude that extensive interaction between an atmosphere dominated by carbon dioxide and a lasting sulphate- and iron-enriched acidic ocean on early Mars is a plausible explanation for the observed absence of carbonates.
- Fairén, A., Dohm, J. M., Baker, V. R., Uceda, E. R., Ruiz, J., Cortés, D., & Amils, R. (2004). Prime candidate sites for the astrobiological exploration of Mars according to its hydrogeological history. European Space Agency, (Special Publication) ESA SP, 201-202.More infoAbstract: Three prime candidate sites for the astrobiological exploration of Mars have been identified on the basis of its hydrogeological history. Each of the sites corresponds to a major inundation phase of the global hydrological model. The Terra Meridiani site is related to the Noachian to Hesperian time, which suggest an aqueous-hydrothermal origin. The Mangala Valles relates to Late Hesperian to Early Amazonian time, where diminishing martian episodic hydrologic events over geologic time are recorded representing a later pulse of tharsis-driven hydrologic activity. The Orcus Patera site relates to Amazonian time, which is a volcanic caldera or impact crater where reduced ponded bodied of water may had existed during almost contemporary times.
- Mahaney, W. C., Milner, M. W., Netoff, D. I., Malloch, D., Dohm, J. M., Baker, V. R., Miyamoto, H., Hare, T. M., & Komatsu, G. (2004). Ancient wet aeolian environments on Earth: Clues to presence of fossil/live microorganisms on Mars. Icarus, 171(1), 39-53.More infoAbstract: Ancient wet aeolian (wet-sabkha) environments on Earth, represented in the Entrada and Navajo sandstones of Utah, contain pipe structures considered to be the product of gas/water release under pressure. The sediments originally had considerable porosity allowing the ingress of living plant structures, microorganisms, clay minerals, and fine-grained primary minerals of silt and sand size from the surface downward in the sedimentary column. Host rock material is of a similar size and porosity and presumably the downward migration of fine-grained material would have been possible prior to lithogenesis and final cementation. Recent field emission scanning electron microscopy (FESEM) and EDS (energy-dispersive spectrometry) examination of sands from fluidized pipes in the Early Jurassic Navajo Sandstone reveal the presence of fossil forms resembling fungal filaments, some bearing hyphopodium-like structures similar to those produced by modern tropical leaf parasites. The tropical origin of the fungi is consistent with the paleogeography of the sandstone, which was deposited in a tropical arid environment. These fossil fungi are silicized, with minor amounts of CaCO3 and Fe, and in some cases a Si/Al ratio similar to smectite. They exist as pseudomorphs, totally depleted in nitrogen, adhering to the surfaces of fine-grained sands, principally quartz and orthoclase. Similar wet aeolian paleoenvironments are suspected for Mars, especially following catastrophic sediment-charged floods of enormous magnitudes that are believed to have contributed to rapid formation of large water bodies in the northern plains, ranging from lakes to oceans. These events are suspected to have contributed to a high frequency of constructional landforms (also known as pseudocraters) related to trapped volatiles and water-enriched sediment underneath a thick blanket of materials that were subsequently released to the martian surface, forming piping structures at the near surface and constructional landforms at the surface. This constructional process on Mars may help unravel the complex history of some of the piping structures observed on Earth; on Earth, evidence for the constructional landforms has been all but erased and the near-surface piping structures exposed through millions of years of differential erosion and topographic inversion now occur as high-standing promontories. If the features on both Earth and Mars formed by similar processes, especially involving water and other volatiles, and since the piping structures of Earth provided suitable environments for life to thrive in, the martian features in the northern plains should be considered as prime targets for physico/mineral/chemical/microbiological analyses once the astrobiological exploration of the red planet begins in earnest. © 2004 Elsevier Inc. All rights reserved.
- Miyamoto, H., Dohm, J. M., Baker, V. R., Beyer, R. A., & Bourke, M. (2004). Dynamics of unusual debris flows on Martian sand dunes. Geophysical Research Letters, 31(13), L13701 1-4.More infoAbstract: Gullies that dissect sand dunes in Russell impact crater often display debris flow-like deposits in their distal reaches. The possible range of both the rheological properties and the flow rates are estimated using a numerical simulation code of a Bingham plastic flow to help explain the formation of these features. Our simulated results are best explained by a rapid debris flow. For example, a debris flow with the viscosity of 102 Pa s and the yield strength of 102 Pa can form the observed deposits with a flow rate of 0.5 m3/s sustained over several minutes and total discharged water volume on the order of hundreds of cubic meters, which may be produced by melting a surface layer of interstitial ice within the dune deposits to several centimeters depth. Copyright 2004 by the American Geophysical Union.
- Miyamoto, H., Dohm, J. M., Beyer, R. A., & Baker, V. R. (2004). Fluid dynamical implications of anastomosing slope streaks on Mars. Journal of Geophysical Research E: Planets, 109(6), E06008 1-14.More infoAbstract: The Mars Global Surveyor mission has imaged slope streaks, some of which have formed in periods as short as 109 days. These features are one of the most currently active surface processes on Mars. Some slope streaks have flow-like morphologic characteristics, which include anastomosing patterns influenced by small topographic barriers. In order to understand what processes gave rise to these specific features, we applied viscoplastic flow numerical modeling techniques to simulated Martian surfaces. We simulate Martian surfaces with observed slope streaks by using Mars Orbiter Laser Altimeter measurements to obtain large-scale slope measurements and a photoclinometry technique on Mars Orbiter Camera images to obtain meter-scale topographic information. Our numerical simulations of slow-moving plastic flows show that a fluid rheology and a short formation period are necessary to explain these features. We estimate that the typical values of bulk viscosity and bulk yield strength are less than 10 Pa s and less than 10 Pa, respectively. The fluid rheology can be explained by a water-related flow with a solid content less than about 20%. An alternative explanation is a dry grain flow with extremely low cohesion and friction angle supported by dispersive pressure or a lubricant, such as electric conditions of particles. The continuous nature of anastomosing slope streaks that originate from point sources is best explained by continuous discharges of material or lubricant. In this case, the estimated flow rate is less than several cubic meters per second, and the flow duration is estimated to be less than a day. Copyright 2004 by the American Geophysical Union.
- Baker, V. R. (2003). Icy martian mysteries. Nature, 426(6968), 779-780.More infoPMID: 14685217;Abstract: Both Mars and Earth have experienced ice ages in geologically recent times. Coincidence of the phenomenon on two planets will further the scientific quest to answer the question of how ice ages originate.
- Fairén, A. G., Dohm, J. M., Baker, V. R., A., M., Ruiz, J., Ferris, J. C., & Anderson, R. C. (2003). Episodic flood inundations of the northern plains of Mars. Icarus, 165(1), 53-67.More infoAbstract: Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems, and the extremely flat northern plains topography at the distal reaches of these outflow channel systems. Paleotopographic reconstructions of the Tharsis magmatic complex reveal the existence of an Europe-sized Noachian drainage basin and subsequent aquifer system in eastern Tharsis. This basin is proposed to have sourced outburst floodwaters that sculpted the outflow channels, and ponded to form various hypothesized oceans, seas, and lakes episodically through time. These floodwaters decreased in volume with time due to inadequate groundwater recharge of the Tharsis aquifer system. Martian topography, as observed from the Mars Orbiter Laser Altimeter, corresponds well to these ancient flood inundations, including the approximated shorelines that have been proposed for the northern plains. Stratigraphy, geomorphology, and topography record at least one great Noachian-Early Hesperian northern plains ocean, a Late Hesperian sea inset within the margin of the high water marks of the previous ocean, and a number of widely distributed minor lakes that may represent a reduced Late Hesperian sea, or ponded waters in the deepest reaches of the northern plains related to minor Tharsis- and Elysium-induced Amazonian flooding. © 2003 Elsevier Inc. All rights reserved.
- Kale, V. S., Mishra, S., & Baker, V. R. (2003). Sedimentary records of palaeofloods in the bedrock gorges of the Tapi and Narmada rivers, central India. Current Science, 84(8), 1072-1079.More infoAbstract: High-magnitude floods are an integral part of the hydrologic systems of the Tapi and Narmada rivers of central India. To establish whether the largest flood in 1970 on Narmada and in 1968 on Tapi had precedence in the geological records, geomorphic studies were undertaken. The main type of palaeoflood evidence is slackwater deposits in bedrock gorges. We have been able to assemble a 2000-year chronology of large floods on Narmada and a < 500-year chronology of floods on Tapi. Evidences of a large late Pleistocene flood on Narmada and early Holocene floods on Tapi have also been identified. Palaeoflood analysis indicates noteworthy clustering of flood events and a discernable link between palaeofloods and Holocene climatic changes.
- Solomon, S. C., Baker, V. R., Bloxham, J., Booth, J., Donnellan, A., Elachi, C., Evans, D., Rignot, E., Burbank, D., Chao, B. F., Chave, A., Gillespie, A., Herring, T., Jean-Loz, R., Labrecque, J., Minster, B., C., W., Simons, M., Turcotte, D. L., & Lou, M. (2003). Plan for living on a restless planet sets NASA's solid earth agenda. Eos, 84(45), 485+491.
- Achyuthan, H., & Baker, V. R. (2002). Coastal response to changes in sea level since the last 4500 BP on the east coast of Tamil Nadu, India. Radiocarbon, 44(1), 137-144.More infoAbstract: Geomorphology, clay mineral composition, and radiocarbon dates from Muttukadu to Marakkanam estuaries and the tidal zone along the east coast of Tamil Nadu, India, have been used to reconstruct coastal evolution between approximately 4500 and 1100 BP. Formation of alternate oyster beds with intervening tidal clay units indicate fluctuation in the sea level may be a consequence of changes in the Mid-Holocene sedimentation pattern and coastal configuration. 14C dates from Muttukadu indicate a rapid relative sea-level rise (RSL) subsequent to 3500 BP and tidal flat sedimentation between 3475 and 3145 BP. Marine conditions along the east coast area returned around 1900 BP. Comparison of dates with other sites, e.g. Muttukadu, Mammallapuram, and Marakkanam, points toward short removal of marine conditions, ample sediment supplies in the tidal zones, and neotectonic activity. Reactivation of the north-south trending fault line occurred not earlier than approximately 1050 BP. Our study indicates that Middle to Late Holocene coastal sedimentation and the chronology of the tidal zone formation have been strongly influenced by local factors. These have provided considerable scope for internal reorganization with changing coastal processes.
- Baker, V. R. (2002). High-energy megafloods: Planetary settings and sedimentary dynamics. International Association of Sedimentologists Special Publications, 3-15.More infoAbstract: High-energy megafloods usually occur in relatively narrow and deep, confined reaches supplied by large volumes of water. Examples of planetary settings include modern and ancient glacial outburst floods (jökulhlaups) of Iceland, glacial lake spillways south of the Pleistocene Laurentide Ice Sheet, the Channeled Scabland of the north-western USA, mountain lake bursts from central Asia, spillways connecting Pleistocene lake basins in Asia, and the immense outflow channels of Mars. The palaeohydraulic analyses of all these floods indicate that they generate values of stream power per unit area (> 103 W m-2) and bed shear stress (> 103 N m-2) that are two orders of magnitude larger than are typical for floods on large alluvial rivers such as the Amazon and Mississippi. Flood discharges can be comparable to flows in ocean currents, indicating important short-term roles in planetary water and sediment fluxes. Significant sedimentary processes in the confined reaches for megafloods include streamlining (and related bar formation), scour around obstacles and giant current ripple (dune) formation. Sediment transport involves the entrainment of large boulders and phenomenally high loading of the flow with extremely course suspended and wash load. The outflux of high-energy, sediment-charged megafloods from confined continental settings to ocean basins results in hyperpycnal flows, and unusually powerful turbidity currents. These have been documented recently for the Pleistocene Missoula floods that formed the Channeled Scabland. They also were probably very important for the Martian outflow channel floods, which may have exerted the primary trigger for climatic change during Mars' geological history.
- Baker, V. R. (2002). The study of superfloods. Science, 295(5564), 2379-2380.
- Baker, V., & Baker, V. R. (2002). Earth sciences. The study of superfloods. Science (New York, N.Y.), 295(5564).
- Fairén, A. G., Dohm, J. M., Ángel, M., & Baker, V. R. (2002). Tharsis-triggered flood inundations of the northern plains of Mars. European Space Agency, (Special Publication) ESA SP, 509-510.More infoAbstract: Throughout the recorded history of Mars, liquid water has shaped its landscape into a number of distinct morphologic types, including prominent features such as the circum-Chryse and recently identified northwestern slope valleys (NSVs, refe. 2, 3) outflow channel systems and the extremely flat northern plains topography at the distal reaches of these outflow channel systems. Paleotopographic reconstructions of the Tharsis magmatic complex in the western hemisphere of Mars have revealed the existence of an enormous Noachian drainage basin/aquifer system in eastern Tharsis; the basin is proposed to source the magmatic-triggered outburst floods that sculpted the circum-Chryse and NSVs outflow channel systems, entrained boulders, rock, and sediment during passage, and ponded to form sequentially through time various hypothesized oceans, seas, and lakes. The water supply of the Noachian basin/aquifer system, however, is thought to have dwindled over time with each endogenic-driven event (insufficient recharge), and thus floods and water bodies (inundations of the northern plains) are expected to be progressively smaller with time.
- Fairén, A. G., Ruiz, J., Ángel, M., Uceda, E. R., Dohm, J. M., & Baker, V. R. (2002). Influence of planetary dynamos in a possible early earth and mars parallel biogeological evolution. European Space Agency, (Special Publication) ESA SP, 451-452.More infoAbstract: The influence of planetary dynamos in a possible early Earth and Mars parallel biogeological evolution was discussed. It was found that the magnetization intensities of the carbonates reflects an ancient magnetic field intensity for Mars. It was suggested that the evolution of both biospheres was different for both Earth and Mars due to the distinct climatic and magnetic histories.
- Ferris, J. C., Dohm, J. M., Baker, V. R., & Maddock, I. (2002). Dark slope streaks on Mars: Are aqueous processes involved?. Geophysical Research Letters, 29(10), 128-1.More infoAbstract: Concentrations of dark slope streaks occur in the equatorial latitudes of Mars, mostly where magmatic-driven activity dominates the geologic record. Although originally ascribed to wet debris flows, all the most recent published hypotheses concerning these features focus on processes which disturb a brighter dusty mantle to expose a darker substrate. These mechanisms invoke dry mass wasting or eolian processes, excluding a role for water. In light of the geographic, geologic, and morphologic considerations, and the new information provided from the Mars Orbital Camera and the Mars Orbital Data Altimeter, we reexamine fluvial processes as a viable explanation for some of the dark slope streaks. In our opinion, two contrasting processes for the formation of dark slope streaks, dust avalanching and spring discharge, represent endpoints on a continuum of progenitors. It may be that some of these features result from dry mass wasting or eolian processes, some from fluvial processes, and some from a mechanism(s) not yet conceived. A spring discharge origin for the formation of the dark slope streaks has profound implications, including Mars having limited, but currently active, fluvial processes acting upon its surface, as well as near-surface aquifers.
- Baker, V. R. (2001). Water and the martian landscape. Nature, 412(6843), 228-236.More infoPMID: 11449284;Abstract: Over the past 30 years, the water-generated landforms and landscapes of Mars have been revealed in increasing detail by a succession of spacecraft missions. Recent data from the Mars Global Surveyor mission confirm the view that brief episodes of water-related activity, including glaciation, punctuated the geological history of Mars. The most recent of these episodes seems to have occurred within the past 10 million years. These new results are anomalous in regard to the prevailing view that the martian surface has been continuously extremely cold and dry, much as it is today, for the past 3.9 billion years. Interpretations of the new data are controversial, but explaining the anomalies in a consistent manner leads to potentially fruitful hypotheses for understanding the evolution of Mars in relation to Earth.
- Costard, F., & Baker, V. R. (2001). Thermokarst landforms and processes in Ares Vallis, Mars. Geomorphology, 37(3-4), 289-301.More infoAbstract: With a length of 1500 km, Ares Vallis is one of the largest martian outflow channels, and is inferred to have been formed by cataclysmic floods of water conveyed from source areas, which are marked by chaotic terrain, to Chryse Planitia. Near its downstream outlet (∼ 14°N, 28°W), the floor of Ares widens to 100 km from its average 25 km width. This area of widened channel floor is marked by a complex of irregular terraces, elongated depressions, linear ridges, sinuous ridges, and other indicators of highly irregular dissection of a formerly continuous surface. Thermokarst processes, following either glacial or alluvial histories, seem best to explain these relationships. Various indicators of fluctuating discharge for water and sediment, ponding of debris, and prolonged flow suggest the emplacement of ice-rich debris in the anomalous reach of Ares Vallis. Post-flood or post-glacial thawing of the ice-rich sediments would then generate the thermokarst landscape. These processes, which are consistent with other indicators of anomalously warm climatic conditions, imply a profound change from the modern martian environment. © 2001 Elsevier Science B.V. All rights reserved.
- Dohm, J. M., Anderson, R. C., Baker, V. R., Ferris, J. C., Rudd, L. P., Hare, T. M., Rice Jr., J. W., Casavant, R. R., Strom, R. G., Zimbelman, J. R., & Scott, D. H. (2001). Latent outflow activity for western Tharsis, Mars: Significant flood record exposed. Journal of Geophysical Research E: Planets, 106(6), 12301-12314.More infoAbstract: Observations permitted by the newly acquired Mars Observer Laser Altimeter data have revealed a system of gigantic valleys northwest of the huge Martian shield volcano, Arsia Mons, in the western hemisphere of Mars (northwestern slope valleys (NSVs)). These features, which generally correspond spatially to gravity lows, are obscured by veneers of materials including volcanic lava flows, air fall deposits, and eolian materials. Geologic investigations of the Tharsis region suggest that the system of gigantic valleys predates the construction of Arsia Mons and its extensive associated lava flows of mainly late Hesperian and Amazonian age and coincides stratigraphically with the early development of the outflow channels that debouch into Chryse Planitia. Similar to the previously identified outflow channels, which issued tremendous volumes of water into topographic lows such as Chryse Planitia, the NSVs potentially represent flooding of immense magnitude and, as such, a source of water for a northern plains ocean.
- Dohm, J. M., Ferris, J. C., Baker, V. R., Anderson, R. C., Hare, T. M., Strom, R. G., Barlow, N. G., Tanaka, K. L., Klemaszewski, J. E., & Scott, D. H. (2001). Ancient drainage basin of the Tharsis region, Mars: Potential source for outflow channel systems and putative oceans or paleolakes. Journal of Geophysical Research E: Planets, 106(E12), 32943-32958.More infoAbstract: Paleotopographic reconstructions based on a synthesis of published geologic information and high-resolution topography, including topographic profiles, reveal the potential existence of an enormous drainage basin/aquifer system in the eastern part of the Tharsis region during the Noachian Period. Large topographic highs formed the margin of the gigantic drainage basin. Subsequently, lavas, sediments, and volatiles partly infilled the basin, resulting in an enormous and productive regional aquifer. The stacked sequences of water-bearing strata were then deformed locally and, in places, exposed by magmatic-driven uplifts, tectonic deformation, and erosion. This basin model provides a potential source of water necessary to carve the large outflow channel systems of the Tharsis and surrounding regions and to contribute to the formation of putative northern-plains ocean(s) and/or paleolakes. Copyright 2001 by the American Geophysical Union.
- House, P. K., & Baker, V. R. (2001). Paleohydrology of flash floods in small desert watersheds in western Arizona. Water Resources Research, 37(6), 1825-1839.More infoAbstract: In this study, geological, historical, and meteorological data were combined to produce a regional chronology of flood magnitude and frequency in nine small basins (7-70 km2). The chronology spans more than 1000 years and demonstrates that detailed records of flood magnitude and frequency can be compiled in arid regions with little to no conventional hydrologic information. The recent (i.e., post-1950) flood history was evaluated by comparing a 50-year series of aerial photographs with precipitation data, ages of flood-transported beer cans, anthropogenic horizons in flood sediments, postbomb 14C dates on flotsam, and anecdotal accounts. Stratigraphic analysis of paleoflood deposits extended the regional flood record in time, and associated flood magnitudes were determined by incorporating relict high-water evidence into a hydraulic model. The results reveal a general consistency among the magnitudes of the largest floods in the historical and the paleoflood records and indicate that the magnitudes and relative frequencies of actual large floods are at variance with "100-year" flood magnitudes predicted by regional flood frequency models. This suggests that the predictive equations may not be appropriate for regulatory, management, or design purposes in the absence of additional, real data on flooding. Augmenting conventional approaches to regional flood magnitude and frequency analysis with real information derived from the alternative methods described here is a viable approach to improving assessments of regional flood characteristics in sparsely gaged desert areas.
- Komatsu, G., Brantingham, P. J., Olsen, J. W., & Baker, V. R. (2001). Paleoshoreline geomorphology of Böön Tsagaan Nuur, Tsagaan Nuur and Orog Nuur: The Valley of Lakes, Mongolia. Geomorphology, 39(3-4), 83-98.More infoAbstract: We conducted a preliminary study of paleoshoreline features associated with Böön Nuur, Tsagaan Nuur, Tsagaab Nuur, and Orog Nuur, lakes located in the Gobi-Altai transition zone of the Valley of Lakes (Dolina Ozor) which stretches from central to western Mongolia. The paleoshoreline features were first identified on RADARSAT satellite SAR imagery. We investigated the features during the 1998 field season of the Joint Mongolian-Russian-American Archaeological Expedition to the Gobi-Altai region. We identified paleoshorelines of multiple elevations in the field, which are considered to be relict beach ridges and wave-cut terraces. Other paleolake landforms include spits and Gilbert-type deltas. These landforms are complex, large and well established, implying that the paleolakes were stable for extended periods. The reconstructed paleolakes cover extensive areas of the valley floor, implying that hydrological and climatic conditions were very different in the past. Paleolake expansions may have occurred under a variety of circumstances. One hypothesis is that the high lake stands occurred during the wetter period corresponding to the Oxygen Isotope Stage 3 prior to the Last Glacial Maximum (LGM), during the warmest early Holocene and the late Holocene, or during all these periods. If low evaporation rates due to lower temperatures, glacier meltwater and possibly increased precipitation are important factors, then the expansions may have occurred during the terminal Late Glacial period after the Last Glacial Maximum. The greatly expanded lakes in the Gobi-Altai could have significantly affected the Quaternary human demography and migration in the region. © 2001 Elsevier Science B.V. All rights reserved.
- Komatsu, G., Gulick, V. C., & Baker, V. R. (2001). Valley networks on Venus. Geomorphology, 37(3-4), 225-240.More infoAbstract: Valley networks on Venus are classified as rectangular, labyrinthic and pitted, or irregular. The venusian valley networks are structurally controlled, as indicated by the morphological patterns of valley branches, consistency between valley and fracture orientations, and associations with the deformed terrains. The morphologies resemble those of terrestrial and martian sapping valleys. Valley networks on Venus probably formed initially from fracture systems and became enlarged by low viscosity lava sapping processes. Subsurface flow of lava may locally have been assisted by surface flows. The lavas probably moved through permeable media and fractures. Venusian valley networks have a higher degree of network integration than do lunar sinuous rilles, but they are less integrated than martian and terrestrial sapping valleys. The viscosity of valley-forming lavas must have been very low, but was not low enough to exploit the permeable media so extensively as to attain a high degree of network integration. The compositions of these lavas may have been mafic to ultramafic or mafic alkaline. Alternatively, the lavas could have had more exotic compositions, such as carbonatite and sulfur. Valley networks are often associated with corona and corona-like features, which are hypothesized to be the surface expressions of mantle plumes. A plume association could mean that the lavas came from the mantle. © 2001 Elsevier Science B.V. All rights reserved.
- Mahaney, W. C., Dohm, J. M., Baker, V. R., Newsom, H. E., Malloch, D., Hancock, R. G., Campbell, I., Sheppard, D., & Milner, M. W. (2001). Morphogenesis of antarctic paleosols: Martian analogue. Icarus, 154(1), 113-130.More infoAbstract: Samples of horizons in paleosols from the Quartermain Mountains of the Antarctic Dry Valleys (Aztec and New Mountain areas) were analyzed for their physical characteristics, mineralogy, chemical composition, and microbiology to determine the accumulation and movement of salts and other soluble constituents and the presence/absence of microbial populations. Salt concentrations are of special interest because they are considered to be a function of age, derived over time, in part from nearby oceanic and high-altitude atmospheric sources. The chemical composition of ancient Mioceneage paleosols in these areas is the direct result of the deposition and weathering of airborne-influxed salts and other materials, as well as the weathering of till derived principally from local dolerite and sandstone outcrops. Paleosols nearer the coast have greater contents of C1, whereas near the inland ice sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, in the order of several million years. Four of the six selected subsamples from paleosol horizons in two ancient soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between 3 and 8 cm, in two profiles, yielded several colonies of the fungi Beauveria bassiana and Penicillium brevicompactum, indicating very minor input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate, and tropical soils and are known to utilize a wide variety of organic carbon and nitrogen compounds. The cold, dry soils of the Antarctic bear a close resemblance to various present and past martian environments where similar weathering could occur and possible microbial populations may exist. © 2001 Elsevier Science.
- Baker, V. R. (2000). 'Saving the appearances' of beach behavior. Journal of Coastal Research, 16(1), iii-iv.
- Baker, V. R. (2000). South American Paleohydrology: Future prospects and global perspective. Quaternary International, 72, 3-5.More infoAbstract: Paleohydrology investigates the past through the reconstructed paleoflows of rivers, ancient lake volumes, groundwater fluctuations, etc. Analytical approaches use theoretical principles to predict paleohydrological parameters, while synthetic approaches rely upon indicators (signs) of past hydrological processes. Analytical approaches are favored in the current fashion of global change science, but these approaches place 'the cart before the horse' because they focus on verifying models rather than on understanding the complexity of nature. South America is an exceptionally important area for synthetic paleohydrology. Discoveries from paleohydrological fieldwork in South America afford the opportunity for understanding Earth's environment and effectively communicating that understanding to the public, to policy makers, and to politicians. As much of the rest of the world engages in an overly polarized analytical approach to global environmental science, South American paleohydrologists have a great opportunity to lead in a more fruitful exploration of reality. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.
- Dohm, J. M., Anderson, R. C., Baker, V. R., Ferris, J. C., Hare, T. M., Strom, R. G., Rudd, L. P., Rice Jr., J. W., Casavant, R. R., & Scott, D. H. (2000). System of gigantic valleys northwest of Tharsis, Mars: Latent catastrophic flooding, northwest watershed, and implications for northern plains ocean. Geophysical Research Letters, 27(21), 3559-3562.More infoAbstract: Mars Orbiter Laser Altimeter (MOLA) reveals a system of gigantic valleys to the northwest of the huge martian shield volcano, Arsia Mons, in the western hemisphere of Mars. These newly identified northwestern slope valleys (NSVs) potentially signify previously undocumented martian catastrophic floods and may corroborate the northern ocean hypotheses. These features, which generally correspond spatially to gravity lows, were previously obscurred in Mariner and Viking Orbiter imagery by veneers of materials, including volcanic lava flows and air fall deposits. Geologic investigations of the Tharsis region suggest that the NSVs were mainly carved prior to the construction of Arsia Mons and its associated Late Hesperian and Amazonian age lava flows, concurrent with the early development of the outflow channels that debouch into Chryse Planitia.
- Greenbaum, N., Schick, A. P., & Baker, V. R. (2000). Re-examination of Bagnold's empirical bedload formulae. Earth Surface Processes and Landforms, 25(9), 1011-1024.More infoAbstract: Bagnold developed his formula for bedload transport over several decades, with the final form of the relation given in his 1980 paper. In this formula, bedload transport rate is a function of stream power above some threshold value, depth and grain size. In 1986, he presented a graph which illustrated the strength of his relation. A double-log graph of bedload transport rate, adjusted for depth and grain size, versus excess stream power was shown to collapse along a line having a slope of 1.5. However, Bagnold based his analyses on limited data. In this paper, the formula is re-examined using a large data set in order to define the most consistent empirical representation, and dimensional analysis is performed to seek a rationalization of the formula. Functional analysis is performed for the final version of the equation defined by Bagnold to determine if the slope of 1.5 is preserved and to assess the strength of the relation. Finally, relations between excess stream power and bedload transport are examined for a fixed slope of 1.5 to assess the performance of various depth and grain size adjustment factors. The rational scaling is found to provide the best result. Copyright (C) 2000 John Wiley and Sons, Ltd.
- Baker, V. R. (1999). Presidential Address: Geosemiosis. Bulletin of the Geological Society of America, 111(5), 633-645.More infoAbstract: Almost alone among modern sciences, geology has preserved a method of inquiry that emphasizes synthetic reasoning for the interpretation of Earth's signified causal processes. Though geologists interpret Earth's signs via all manner of measurement, quantitative modeling, and experimentation, these are but tools for an inquiry ultimately directed at the truth of Earth's message. Geologists have always considered that message to be signified in rocks, sediments, fossils, and other signs of Earth processes. To interpret these signs, geologists do not need a foundational metaphysics to ground their reasoning, as Lyell attempted with his uniformitarianism. Instead, geologists can benefit from understanding the formal conditions of what will count as true in these signs, a topic explored through the branch of philosophy known as semiotics. The geologically relevant philosophy involves a semiotic point of view wherein signs are not mere objects of thought or language, but rather are vital entities comprising a web of signification that is continuous from outcrops to reasoning about outcrops. Such an action of signs constitutes a geosemiosis that leads geological investigators on a fruitful course of hypothesis generation. Semiotic grammar provides the means to describe the representational character of signification that is inherent in this geological reasoning. Critical logic explores the modes of inference used to seek truth in the representations, and georhetoric attains truth as a matter of belief. While not being a method for doing geology, semiotics provides a means of describing the highly productive reasoning processes of geologists.
- Baker, V. R. (1999). Presidential address: Geosemiosis. Bulletin of the Geological Society of America, 111(5), 633-645.More infoAbstract: We decipher the Earth's diary that has been left us as a legacy. We read with trained senses and interpret with the tools of disciplined thinking. We translate the Earth's language into our own, and enrich the already bright and colourful surface of the present with the knowledge of the inexhaustible abundance of the past. Almost alone among modern sciences, geology has preserved a method of inquiry that emphasizes synthetic reasoning for the interpretation of Earth's signified causal processes. Though geologists interpret Earth's signs via all manner of measurement, quantitative modeling, and experimentation, these are but tools for an inquiry ultimately directed at the truth of Earth's message. Geologists have always considered that message to be signified in rocks, sediments, fossils, and other signs of Earth processes. To interpret these signs, geologists do not need a foundational metaphysics to ground their reasoning, as Lyell attempted with his uniformitarianism. Instead, geologists can benefit from understanding the formal conditions of what will count as true in these signs, a topic explored through the branch of philosophy known as semiotics. The geologically relevant philosophy involves a semiotic point of view wherein signs are not mere objects of thought or language, but rather are vital entities comprising a web of signification that is continuous from outcrops to reasoning about outcrops. Such an action of signs constitutes a geosemiosis that leads geological investigators on a fruitful course of hypothesis generation. Semiotic grammar provides the means to describe the representational character of signification that is inherent in this geological reasoning. Critical logic explores the modes of inference used to seek truth in the representations, and georhetoric attains truth as a matter of belief. While not being a method for doing geology, semiotics provides a means of describing the highly productive reasoning processes of geologists.
- Enzel, Y., Ely, L. L., Mishra, S., Ramesh, R., Amit, R., Lazar, B., Rajaguru, S. N., Baker, V. R., & Sandler, A. (1999). High-resolution holocene environmental changes in the Thar Desert, northwestern India. Science, 284(5411), 125-128.More infoAbstract: Sediments from Lunkaransar dry lake in northwestern India reveal regional water table and lake level fluctuations over decades to centuries during the Holocene that are attributed to changes in the southwestern Indian monsoon rains. The lake levels were very shallow and fluctuated often in the early Holocene and then rose abruptly around 6300 carbon-14 years before the present (14C yr B.P.). The lake completely desiccated around 4800 14C yr B.P. The end of this 1500-year wet period coincided with a period of intense dune destabilization. The major Harrapan-Indus civilization began and flourished in this region 1000 years after desiccation of the lake during arid climate and was not synchronous with the lacustral phase.
- Baker, V. R. (1998). Catastrophism and uniformitarianism: logical roots and current relevance in geology. Geological Society Special Publication, 143, 171-182.More infoAbstract: This paper is included in the Special Publication entitled 'Lyell: the past is the key to the present', edited by D.J. Blundell and A.C. Scott. Catastrophism in the Earth sciences is rooted in the view that Earth signifies its causative processes via landforms, structures and rock. Processes of types, rates and magnitudes not presently in evidence may well be signified this way. Uniformitarianism, in contrast, is a regulative stipulation motivated by the presumed necessity that science achieves logical validity in what can be said (hypothesized) about the Earth. Regulative principles, including simplicity, actualism and gradualism, are imposed a priori to insure valid inductive reasoning. This distinction lies at the heart of the catastrophist versus uniformitarian debates in the early nineteenth century and it continues to influence portions of the current scientific program. Uniformitarianism, as introduced by Charles Lyell in 1830, is specifically tied to an early nineteenth century view of inductive inference. Catastrophism involves a completely different form of inference in which hypotheses are generated retroductively. This latter form of logical inference remains relevant to modern science, while the outmoded notions of induction that warranted the doctrine of uniformitarianism were long ago shown to be overly restrictive in scientific practice. The latter should be relegated solely to historical interest in the progress of ideas.
- Baker, V. R. (1998). Hydrological understanding and societal action. Journal of the American Water Resources Association, 34(4), 819-825.More infoAbstract: Hydrology is both an applied practical science and a pure geophysical science. The goal of hydrology, as a geophysical science, is to achieve theories capable of explaining with satisfactory accuracy the phenomena of interest. Through the rapidly accelerating power and versatility of digital computing technology, theory development and application are immensely facilitated via increasingly sophisticated predictive modeling schemes, which are now the principal operating tools both for applied management hydrology and for basic geophysical hydrology. While this approach treats phenomena as classes or generalizations, social and behavioral scientists have long argued that human beings base their actions on percepts, i.e., on the concrete specifics of their experience. Thus, the commonly held ideal of basing policy, decisions, and public actions on the best possible science encounters a conflict in belief systems. A possible resolution of this dilemma lies in the use of observational components, which in concept-centered science serve as data to test or calibrate models. These components also serve as a great repository of natural experience that is closely attuned to the perceptual reality that propels societal action. Landscapes and sediments provide indices of real processes, whose occurrence can be expected by continuity to extend to present and future activity. More attention to research on such indices is warranted as a means of triggering perception-based action by responsible decision-makers. Grounded in reality, and tempered by their intrinsic fallibility, the scientifically powerful conceptual schemes (models) will then serve as guides to further action. The full societal benefit of hydrological science requires a balanced approach in which subdisciplines focused on environmental indices are afforded equal attention to those focused on conceptual idealization.
- Greenbaum, N., Margalit, A., Schick, A. P., Sharon, D., & Baker, V. R. (1998). A high magnitude storm and flood in a hyperarid catchment, Nahal Zin, Negev Desert, Israel. Hydrological Processes, 12(1), 1-23.More infoAbstract: In October 1991 a high magnitude rainstorm flood, estimated return period 40 years, occurred in Nahal Zin, a 1400 km2 catchment in the hyperarid Negev Desert. The meso-scale structure of the storm was a curved squall line that developed from a thunderstorm in accordance with the topography of the catchment divide, by which it was strongly affected. Tropical moisture reached the area via the subtropical jet stream, in conjunction with a lower level northward intrusion of the Red Sea trough (RST-N) into the Mediterranean Sea. Rainfall, as measured at the few and sparse gauging stations, was much too small to account for the resulting large flood. Peak flow and other hydraulic characteristics of the flood were indirectly reconstructed. The techniques of palaeoflood hydrology used were based on sedimentological evidence of fine-grained flood sediments deposited in back-flooded tributaries, as well as on other stage indicators. The HEC-2 procedure was employed to determine water surface profiles. The spatial and temporal characteristics of the event were studied through a combination of rainstorm analysis, remote sensing, hydrological and sedimentological data; they jointly explain the magnitude and timing of tributary contributions producing the integrated flood in the main channel. The flood as reconstructed reveals a three-peak hydrograph: two peaks were generated by the same storm but had different floodwave arrival times in the main channel; the third resulted from a local rainstorm which occurred on the following day and covered only one tributary. The curved structure of the storm and its dynamics in relation to catchment orientation resulted in storm movement in tandem with the floodwave. The synchronous contribution from all main tributaries preserved evidence of the floodwave both in stage and volume by replacing the transmission losses in the sections with thick alluvium. Other high magnitude floods on record for the large Negev Desert catchments are caused by a cold upper air incursion associated with the RST-N. Most of them occur in the autumn and are caused by storms with high-intensity rainfall. This is in stark contrast with the flooding behaviour of the semi-arid zone further north, which is linked primarily to the core of the Mediterranean winter. The complexities involved in the generation of a large desert flood, as revealed by this study, illustrate the fallacy of applying routine hydrological modelling to such events, and underline the need to study the processes involved in adequate detail. © 1998 John Wiley Sons, Ltd.
- Kwoun, O., Crawford, M. M., Baker, V. R., & Komatsu, G. (1998). Variable resolution topographic mapping of ancient fluvial landscapes in Australia. International Geoscience and Remote Sensing Symposium (IGARSS), 5, 2360-2362.More infoAbstract: Topographic features often exhibit great spatial variability over a region and can thereby be represented efficiently on variable resolution grids. Repeat pass INSAR from space-based sensors has relatively coarse spatial resolution but broad coverage and can be used effectively to develop regional digital elevation models (DEM's), while airborne TOPSAR provides superior spatial and vertical resolution but limited coverage. This study investigates the application of the Distributed Adaptive Grid Hierarchy (DAGH) data structure for developing an integrated, interferometry based DEM of the regional landscape of the Finke River in the Northern Territory of Australia using ERS and TOPSAR data.
- Peng, C., Duckstein, L., Davis, D. R., & Baker, V. R. (1998). Flood estimation by combining gauged and paleo data. Proceedings of the Annual Water Resources Planning and Management Conference, 425-430.More infoAbstract: In this paper, the Salt River basin possessing paleoflood study has been selected for flood estimations. By plotting the flood data on log-normal probability paper, it is found that the trend of high floods, whose peaks are greater than 2,400 m3/s, deviates from the straight line fitted to the gauged flood data and the trend of these high floods is similar to that of the paleofloods. Thus, it is reasonable to assume that these high floods belong to different probability distributions than that of the rest. The distributions for the high values of gauged flood data and the paleoflood data are assessed by linear regression using their plotting positions on probability paper. Then, a Bayesian statistical approach is applied to combine the gauged flood data and paleoflood data. The floods estimated by the combined distribution are much lower than those obtained by the conventional methods. For example, the 100 year flood estimated by the combined distribution is about 60% of that obtained by a Pearson type III distribution.
- Kale, V. S., Hire, P., & Baker, V. R. (1997). Flood Hydrology and Geomorphology of Monsoon-dominated Rivers: The Indian Peninsula. Water International, 22(4), 259-265.More infoAbstract: The rivers of the southern part of the Indian Peninsula are monsoonal in nature and the hydrological characteristics of these rivers differ markedly from those of Himalayan rivers. The rivers are subjected to severe floods during the monsoon season. In the last few decades, several large-magnitude floods (peak floods between 10,000 and 80,000 m3/s) have been recorded. In general, floods caused by precipitation from Bay of Bengal depressions include the peak flood of record. Analyses of the systematic, historical, and paleoflood records indicate that, in recent decades, the frequency of high-magnitude floods has increased significantly. Hydraulic estimates reveal that high flows are capable of bedrock erosion and transportation of coarse material. Such large floods are important, not only from the standpoint of geomorphic work, but also in terms of social impact. Floods in the peninsular region are responsible for colossal loss of human life, crops, and property. In recent years, various measures of flood control and management have been adopted. However, flooding in such large rivers profoundly challenges flood-hazard management, because of the inadequacy of conventional data and high spatio-temporal variability of floods. To understand flood hazards and environmental change it is imperative that engineers and hydrologists utilize historical and paleoflood records to improve risk analyses as well as to estimate probable maximum flood on rivers such as these in a highly flood-prone region.
- Kale, V. S., Mishra, S., & Baker, V. R. (1997). A 2000-year palaeoflood record from Sakarghat on Narmada, central India. Journal - Geological Society of India, 50(3), 283-288.More infoAbstract: A continuous record of the largest Narmada floods over the last 2000 years was obtained from Sakarghat, on the Narmada River, from a study of slackwater flood deposits. Two sequences of extreme floods date between ca. 400 and 1000 AD and post-1900 AD. The period 400-1000 AD, representing a period of less frequent but more extreme floods, has been documented in the archaeological record as one of decline of human settlements.
- Komatsu, G., & Baker, V. R. (1997). Paleohydrology and flood geomorphology of Ares Vallis. Journal of Geophysical Research E: Planets, 102(E2), 4151-4160.More infoAbstract: Ares Vallis is a Martian outflow channel which is about 1500 km long and locally exceeds 100 km in width and 1000 m in depth. We estimate the channel's paleoflow capacity using paleohydraulic techniques. At a constricted and unusually deep reach, not affected by tributaries or secondary inflows, the estimated possible maximum peak discharges are of the order of 108-109 m3/s. These values are 1 to 2 orders of magnitude larger than any known terrestrial floods. These high-discharge flows were theoretically capable of transporting boulders larger than 10 m in diameter. The downstream depositional plain, where Ares debauches into the Chryse Planitia, displays geomorphological features indicative of high erosional capacity by the flooding. In this area, site of the proposed Pathfinder landing, we expect to find a complex sequence of sediments created by varying paleoflood flow hydraulics, sediment transport characteristics, and probable secondary modification of the primary flood landforms. Copyright 1997 by the American Geophysical Union.
- Baker, V. R. (1996). Discovering Earth's future in its past: Palaeohydrology and global environmental change. Geological Society Special Publication, 115, 73-83.More infoAbstract: Palaeohydrology is the study of various past aspects of the hydrological cycle. It is accomplished by interpreting indices of past hydrological processes. By its focus on the effects of realized processes, palaeohydrology provides a critical scientific complement to studies that idealize hydrological systems in order to predict future change. Future habitability of the planet will surely require the guidance of scientific concepts, but it will also require a basis in the perception of change that compels people to act. Human perception is grounded in the concrete particulars of reality, not in the abstract idealizations of theoretical science. While we scientists may wish otherwise, say for a more enlightened public and political sector, it is pragmatic not to expect such on the short time scale of potential detrimental changes for Earth's habitability to humankind. The greatest repository of scientific knowledge for stimulating human perception is the geological past. This experience of the Earth is the only real evidence of global environmental change available. It can function scientifically as a source of data with which to test models of change, confirming or falsifying theoretical extrapolations to past states (retrodictions). However, its more important role is as a source of discovery. In the geological record the scientist can discover previously unanticipated realizations of hydrological processes that will require new or revised models (hypotheses) for their explanation. It is our challenge as scientists to devote as much effort to exploring this real world of Earth experience as we currently apply to idealizing the abstract world of Earth systems.
- Baker, V. R. (1996). Evolutionary megageomorphology of the terrestrial planets. Heidelberger Geographische Arbeiten, 104, 3-12.More infoAbstract: Geomorphology can be viewed alternatively as (1) a body of knowledge or facts about planet Earth's surface, or (2) a way of thinking about Earth's surface. Viewpoint (1) leads logically to a reductionistic epistemological emphasis on establishing simplifying and generalizing principles from which one might construct model simulations of landscape evolution and process operation. This viewpoint also leads to an emphasis upon readily measurable processes. The controlled experiments necessary to match reality to theory via model predictions are logically precluded in the real world of planetary surfaces. Viewpoint (2) offers a holistic approach to discovery based on the recognition that the book of Earth's surface is written in a language of indices. Indices are signs that directly represent causative processes. The holistic, evolutionary thought process is needed not only at megascales; it also is required for geoecological understanding of humankind's immediate environment. There is only one required principle for the necessary scientific processes: do not block the evolution of thought.
- Baker, V. R. (1996). The pragmatic roots of American Quaternary geology and geomorphology. Geomorphology, 16(3), 197-215.More infoAbstract: H.L. Fairchild's words from the 1904 Geological Society of America Bulletin remain appropriate today: "Geologists have been too generous in allowing other people to make their philosophy for them". Geologists have quietly followed a methodological trinity involving (1) inspiration by analogy, (2) impartial and critical assessment of hypotheses, and (3) skepticism of authority (prevailing theoretical constraints or paradigms). These methods are described in classical papers by Quaternary geologists and geomorphologists, mostly written a century ago. In recent years these papers have all been criticized in modern philosophical terms with little appreciation for the late 19th century American philosophical tradition from which they arose. Recent scholarly research, however, has revealed some important aspects of that tradition, giving it a coherence that has largely been underappreciated as 20th century philosophy of science pursued its successive fads of logical positivism, critical rationalism, relativism, and deconstructivism - for all of which "science" is synonymous with "physics". Nearly all this ideology is geologically irrelevant. As philosophy of science in the late 20th century has come to be identical with philosophy of analytical physics, focused on explanations via ideal truths, much of geology has remained true to its classical doctrines of commonsensism, fallibilism, and realism. In contrast to the conceptualism and the reductionism of the analytical sciences, geology has emphasized synthetic thinking: the continuous activity of comparing, connecting, and putting together thoughts and perceptions. The classical methodological studies of geological reasoning all concern the formulation and testing of hypotheses. Analysis does not serve to provide the ultimate answers for intellectual puzzles predefined by limiting assumptions imposed on the real world. Rather, analysis in geology allows the investigator to consider the consequential effects of hypotheses, the latter having been suggested by experience with nature itself rather than by our theories of nature. These distinctions and methods were described in G.K. Gilbert's papers on "The Inculcation of Scientific Method by Example" (1886) and "The Origin of Hypotheses" (1896). Portions were elaborated in T.C. Chamberlin's "Method of Multiple Working Hypotheses" (1890) and his "Method of the Earth Sciences" (1904); in W.M. Davis's "Value of Outrageous Geological Hypotheses" (1926); and in D. Johnson's "Role of Analysis in Scientific Investigation" (1933). American Quaternary geology and geomorphology have their philosophical roots in the pragmatic tradition, enunciated most clearly by C.S. Peirce, now recognized as the greatest American philosopher and considered by Sir Karl Popper to be one of the greatest philosophers of all time. Quaternary geology and geomorphology afford numerous examples of Peirce's "method" of science, which might be termed "the critical philosophy of common sense". The most obvious influence of pragmatism in geology, however, has largely been conveyed by the tradition of its scientific community. The elements of this tradition include a reverence for field work, a humility before the "facts" of nature, a continuing effort "to discriminate the phenomena observed from the observer's inference in regard to them", a propensity to pose hypotheses, and a willingness to abandon them when their consequences are contradicted by reality.
- Ely, L. L., Enzel, Y., Baker, V. R., Kale, V. S., & Mishra, S. (1996). Changes in the magnitude and frequency of late Holocene monsoon floods on the Narmada River, central India. Bulletin of the Geological Society of America, 108(9), 1134-1148.More infoAbstract: During the past three decades, the Narmada River of monsoon-dominated central India has undergone extraordinarily large floods that rank among the highest recorded rainfall-runoff discharges per drainage area in the world. The floods on this river are a direct result of intense tropical cyclones embedded within the summer monsoon circulation. The cluster of extreme floods in the past few decades represents an anomalous increase in both the magnitude and frequency of large floods when compared with the >1700 yr record of paleoflood deposits on this river. Sand deposits from recent floods consistently blanket older flood deposits at numerous slack-water paleoflood sites along a 15 km reach of the Narmada River. At the site of the highest flood deposits, 4-5 sandy flood deposits yielding post-A.D. 1950 14C dates cap an underlying sequence of 7-10 silty flood deposits with a minimum 14C age of 650 ± 70 B.P. and a maximum age older than 1720 ± 185 B.P. The post-A.D. 1950 floods are thus the largest in at least the past several hundred years. An undisturbed surface archaeological site of microlithic artifacts
- Enzel, Y., Ely, L. L., House, P. K., & Baker, V. R. (1996). Magnitude and frequency of Holocene palaeofloods in the southwestern United States: A review and discussion of implications. Geological Society Special Publication, 115, 121-137.More infoAbstract: Data about the magnitude and time of occurrence of palaeofloods from the lower Colorado River basin enable us to test two long-standing hypotheses which have affected many studies and applications in the field of flood hydrology. The two hypotheses are (a) the existence of an upper boundary to flood magnitudes and whether there is a possibility of determining it from the existing data, and (b) the random occurrence versus clustering of the large floods through time. Earlier observations on regional flood envelope curves indicated the existence of an upper limit for flood magnitudes, but these studies limited their conclusions because of the short length of the systematic gauged data. This limitation is overcome here because palaeoflood data cover a much longer period of observation. Palaeoflood studies provide information about the largest individual floods experienced in many rivers in a specific region occurring over the last millennia. In the southwestern US, this information demonstrates that, even when the length of observational data increases to centuries and millennia, there is no change in the stabilized, regional envelope curves constructed from gauged and historical flood records. This pattern supports the hypothesis of an upper limit to flood magnitudes and points to a method for testing this hypothesis in other regions. There are surprising similarities between the envelope curve of the palaeoflood data and the envelope curve for the gauged and historical data in the lower Colorado River basin. These similarities indicate that in regions of the world where flood data is sparse envelop curves based on palaeoflood studies can provide basic data for engineering design purposes and other hydrological applications. The random occurrence of large floods in time is tested by constructing chronologies for the largest palaeofloods in several basins in the lower Colorado River basin. These chronologies indicate a clustering of the large floods in specific time periods. The similarity between the various time periods characterized by high- and low-flooding and other palaeoclimatic indicators from the southwestern Untied States seems best explained by a climatic control on flood frequency over the last 5000 years.
- Enzel, Y., Ely, L. L., House, P. K., & Baker, V. R. (1996). Magnitude and frequency of Holocene palaeofloods in the southwestern United States: a review and discussion of implications. Global continental changes: the context of palaeohydrology, 121-137.More infoAbstract: Data about the magnitude and time of occurrence of palaeofloods from the lower Colorado River basin enable us to test two long-standing hypotheses which have affected many studies and applications in the field of flood hydrology. The two hypotheses are (a) the existence of an upper boundary to flood magnitudes and whether there is a possibility of determining it from the existing data, and (b) the random occurrence versus clustering of the large floods through time. Earlier observations on regional flood envelope curves indicated the existence of an upper limit for flood magnitudes, but these studies limited their conclusions because of the short length of the systematic gauged data. This limitation is overcome here because palaeoflood data cover a much longer period of observation. Palaeoflood studies provide information about the largest individual floods experienced in many rivers in a specific region occurring over the last millennia. In the southwestern US, this information demonstrates that, even when the length of observational data increases to centuries and millennia, there is no change in the stabilized, regional envelope curves constructed from gauged and historical flood records. This pattern supports the hypothesis of an upper limit to flood magnitudes and points to a method for testing this hypothesis in other regions. There are surprising similarities between the envelope curve of the palaeoflood data and the envelope curve for the gauged and historical data in the lower Colorado River basin. These similarities indicate that in regions of the world where flood data is sparse envelope curves based on palaeoflood studies can provide basic data for engineering design purposes and other hydrological applications. The random occurrence of large floods in time is tested by constructing chronologies for the largest palaeofloods in several basins in the lower Colorado River basin. These chronologies indicate a clustering of the large floods in specific time periods. The similarity between the various time periods characterized by high- and low-flooding and other palaeoclimatic indicators from the southwestern US seems best explained by a climatic control on flood frequency over the last 5000 yr.
- Kale, V. S., Baker, V. R., & Mishra, S. (1996). Multi-channel patterns of bedrock rivers: An example from the central Narmada basin, India. Catena, 26(1-2), 85-98.More infoAbstract: An anomalous multiple channel pattern in bedrock is observed on a predominantly downcutting reach of the Narmada River. The multi-channel reach (800-2750 m in width and 8500 m in length) is bounded by major faults, and is underlain by granite and gneiss bedrock. Geomorpho-logical investigations reveal differences among the upstream, middle and downstream sub-reaches of the multi-channel study area. Whereas the upstream sub-reach is dominated by deep flows and fine sediments, the lower sub-reach is characterized by a steep gradient and rapids. The middle sub-reach is the widest, and is marked by thickly forested islands and boulder berms. The characteristics of the three different sub-reaches suggest control by the interactions of lithology, flood processes and tectonics. Estimations of Hack's (1973) stream-gradient index values indicate considerable variations for the SL values along the length of Narmada River. The highest value of gradient index (SL = 797) is associated with the multi-channel reach, implying lithologic or tectonic control. Given the dimensions of the reach and its channels, it appears that the present hydrological regime is inadequate to produce the feature. We hypothesize that the multi-channel pattern development in bedrock was initiated by block or domal uplift. Enhanced gradients and extreme floods permitted the system to exploit linear weaknesses in the bedrock, leading to the development of anabranches and establishment of multiple channels in bedrock. Abrupt changes in the channel planform and morphology at the study site indicate that the river is adjusting its channel geometry (width, depth, gradient and plan configuration) to a new equilibrium channel morphology through the action of the extreme floods characteristic of this fluvial environment. © 1996 Elsevier Science B.V. All rights reserved.
- Kale, V. S., Ely, L. L., Enzel, Y., & Baker, V. R. (1996). Palaeo and historical flood hydrology, Indian Peninsula. Geological Society Special Publication, 115, 155-163.More infoAbstract: The Indian Peninsula has many rivers that flow through bedrock gorges, providing excellent sites for the emplacement and preservation of late Holocene slackwater sediments and palaeostage indicators. Preliminary surveys of palaeoflood hydrology at these sites and the available historical data (since 1700) indicate considerable spatial and temporal variability of the largest flood events. There appear to be complex associations with the monsoon and with the El Niño-Southern Oscillation phenomenon that will require further study as more palaeoflood records are developed at the study sites. Data available thus far indicate a modern (post-1950) epoch of very large floods that may exceed the magnitudes of events over the last millennium.
- Kale, V. S., Ely, L. L., Enzel, Y., & Baker, V. R. (1996). Palaeo and historical flood hydrology, Indian Peninsula. Global continental changes: the context of palaeohydrology, 155-163.More infoAbstract: The Indian Peninsula has many rivers that flow through bedrock gorges, providing excellent sites for the emplacement and preservation of late Holocene slackwater sediments and palaeostage indicators. Preliminary surveys of palaeoflood hydrology at these sites and the available historical data (since 1700) indicate considerable spatial and temporal variability of the largest flood events. There appear to be complex associations with the monsoon and with the El Nino-Southern Oscillation phenomenon that will require further study as more palaeoflood records are developed at the study sites. Data available thus far indicate a modern (post-1950) epoch of very large floods that may exceed the magnitudes of events over the last millennium.
- Komatsu, G., & Baker, V. R. (1996). Channels in the solar system. Planetary and Space Science, 44(8), 801-815.More infoAbstract: Among the major discoveries made by planetary missions, channel structures, formed by a wide range of fluids such as water and lavas, have proven to be surprisingly common. Recent identification of gigantic flood channels in continental regions and submarine channels on the continental shelves provide new channel categories to an already rich inventory of terrestrial channels. Sinuous riles on the Moon, once hypothesized to have formed by water action, now constitute an important lava channel type. Mars has abundant evidence of an ancient warm-wet climate recorded in the channels, including an outflow channel which is the widest (∼200 km) known in the Solar System. Some lava channels observed on the flanks of the huge Martian shield volcanoes seem to have been modified by water. The Magellan radar mission revealed a wide range of volcanism on Venus. Most unusual is the great variety of channels produced by large-scale, low-viscosity lava eruptions. This includes potentially the longest channel in the Solar System (6800 km). Venusian atmospheric conditions alone do not produce sufficient differences in the lavas' cooling rates to explain the formation of many Venusian channels. The origin of these channels must be explained by eruption parameters, probable high discharge rates, high temperatures, long duration, and the possible involvement of very fluid silicates or lavas of exotic composition. Copyright © 1996 Elsevier Science Ltd.
- Baker, V. R. (1995). Global paleohydrological change. Quaestiones Geographicae, 27-35.More infoAbstract: In studying the past, paleohydrologists employ synthetic reasoning, using retroductive (causal) inference, to interpret indices (signs) of ancient processes that reveal the natural patterns (habits) of Earth experience through time and space. Discovery of anomalous phenomena leads to the need for revising prior conceptualizations (models), reformulating them to be more in accord with reality. An example is the recent discovery in tropical river paleoflood records that large floods may be preferentially clustered in recent decades. If corroborated by further study, this may indicate an influence of global greenhouse warming on monsoonal circulation and tropical storms. Such change could have profound implications for global habitability. -from Author
- Baker, V. R., Ely, L. L., Enzel, Y., & Kale, V. S. (1995). Understanding India's Rivers: late Quaternary palaeofloods, hazard assessment and global change. Memoirs - Geological Society of India, 32, 61-77.More infoAbstract: To understand flood hazards and environmental change one needs scientific experience of such change as a complement to the conceptualization of that change. One of many ways to make this possible is through the recent scientific breakthrough in studying slackwater deposit and palaeostage indicators in stable-boundary fluvial reaches. Interestingly, the three or four largest local events in this sequence occurred in the last half century, and floods throughout this record appear clustered in time. These results have important implications for understanding climate change and the risks posed by major floods to people and their works. -from Authors
- Finn, V. S., Baker, V. R., Dolginov, A. Z., Gabitov, I., & Dyachenko, A. (1995). Large-scale spatial patterns in topography at Alpha Regio, Venus. Geophysical Research Letters, 22(14), 1901-1904.More infoAbstract: The spatial patterns of topographic features near Alpha Regio have the following attributes: quasi-circular shapes of individual elements; a hierarchy of distinctive sizes for those elements, with diameters of various elements and a large-scale arrangement or pattern in which the highland plateau of Alpha Regio is surrounded by a ring of 500-km structures, all of which constitute a 2800-km megastructure. It is hypothesized that the intricate patterns of hierarchical scaling result from complex mantle convection. -from Authors
- Gregory, K. J., Starkel, L., & Baker, V. R. (1995). Global continental palaeohydrology. Global continental palaeohydrology.More infoAbstract: This volume provides a background for an international research project on global continental palaeohydrology over the last 20 000 yr established as a Commission by INQUA, in 1991. Following an introductory chapter the remaining 13 chapters are organised in three sections: part I contains six chapters on particular aspects of change relevant to global palaeohydrology of continental areas, such as the impact of large ice sheets on continental palaeohydrology, vegetation and lake level change, human activity and palaeohydrology; in part II five chapters review the state of knowledge in the four major zones identified for the purposes of the research project, ie the humid tropics, arid and semi-arid regions, the temperate zone, and polar and subpolar regions; the concluding part contains a section on a database for global continental palaeohydrology, and an outline research programme. -G.E.Hodgson
- Baker, V. R. (1994). Geomorphological understanding of floods. Geomorphology, 10(1-4), 139-156.More infoAbstract: The summer 1993 flooding of the upper Mississippi River valley reminds us that floods are the most globally pervasive, environmentally diverse and continually destructive of all natural hazards. The fact that flood damages continue to rise raises commonsense questions about conventional flood science. Like much modern environmental science, conventional flood science has followed the model of theoretical physics. It advanced from early emphasis on streamflow measurement to the use of simple formulae, and finally to the abstract theoretical sophistication of modern modeling studies. Two approaches are now used to "predict" flood phenomena: (1) beginning with the conventional database of measured properties of small common floods, a conceptual generalization is made to the idealized properties of the large, rare floods from which society is assumed to be at risk, and (2) explanation of detailed, specific flood phenomena is achieved through theoretical generalization (models) based on "first principles", which are assumed to apply to the entire class of phenomena. Unfortunately, both approaches devote almost all their attention to methodology, increasingly mathematical, without questioning basic underlying assumptions. Increasingly it is the assumptions, often unstated, that serve to embody the understanding of floods as real-world particular phenomena, rather than as conceptual generalities. Such trends lead to an unease that it is not floods that are being researched by much of conventional flood science. Rather, such flood "science" is increasingly becoming the mathematical manipulation of idealized parameters that are assumed to have flood-like properties. These idealizations of flood attributes are generalized, and the resulting predicted consequences are imposed upon society through engineering designs, flood-hazard zonations, and the like. Geomorphological understanding of floods derives a from along geological tradition of studying indices of real processes operating in the past. In contrast to the conceptual, theoretical treatment of floods as classes or generalizations, geomorphologists study particular floods revealed as a natural experience that is recorded in the sediments, landforms, and erosional scars of past floods. The strength of this approach is in its affinity to the commonsense perceptional basis that underpins human action. Geomorphological flood studies, including recent advances in paleoflood hydrology, are needed as a complement to conventional hydrological approaches. The resulting complementarity will allow the predictions of the conventional approach to be grounded in the concrete particulars of experience. Without such grounding, flood science risks continuing as an empty quest for universal ideals while humanity, paralyzed by inaction, continues to suffer from the reality of particular floods. © 1994.
- Baker, V. R., Finn, V. S., & Christersson, L. (1994). Soviet and post-soviet science . Science, 265(5170), 301-302.More infoPMID: 17838021;
- Johnson, J. R., & Baker, V. R. (1994). Surface Property Variations in Venusian Fluidized Ejecta Blanket Craters. Icarus, 110(1), 33-70.More infoAbstract: A comprehensive study of Magellan Cycles 1 and 2 radar data from Venus reveals surface roughness and dielectric variations associated with fluidized ejecta blanket (FEB) craters that help illuminate styles of flow ejecta emplacement. This study develops new procedures of digital unit mapping and polygon-filling algorithms using Magellan SAR, altimetry, and radiometry data. These techniques allow the extraction of radiophysical information for FEB crater materials, nearby plains, and lava flows such as (1) their specific backscatter (σo) behavior (relative to each other and to terrestrial lava surfaces); (2) average calculated values of emissivity, rms slopes, corrected reflectivity, and the diffuse component of reflectivity; and (3) variations in radar properties along longitudinal traverses that are best explained by surface roughness trends at several spatial scales and/or dielectric variations. Backscatter curve slopes of the FEBs studied here are consistent with surface textures that are transitional between a'a and pahoehoelike. Average surface property values of ejecta units are relatively similar for a given crater, but are discernibly different from other craters. Individual crater ejecta reflectivity and emissivity values are relatively similar to those for the surrounding plains, which may suggest a link between plains material and ejecta dielectric properties. Increasing FEB roughness downflow are interpreted to be associated with more lava-like flows, while decreasing roughnesses are more similar to trends typical of gravity (pyroclastic-like or debris-like) flows. Most commonly, FEB crater flow materials exhibit transitions from proximal, lava/melt-like flow styles to distal, gravity flow-like styles. Some FEBs show more complicated behavior, however, or appear to be more dominated by dielectric differences downflow, as inferred from correlations between the data sets. Such transitions may result from changes in local topography or from overlapping of flow lobes during FEB emplacement. © 1994 Academic Press. All rights reserved.
- Kale, V. S., Ely, L. L., Enzel, Y., & Baker, V. R. (1994). Geomorphic and hydrologic aspects of monsoon floods on the Narmada and Tapi Rivers in central India. Geomorphology, 10(1-4), 157-168.More infoAbstract: High-magnitude floods during the monsoon season are considered to be India's recurring and leading natural disaster. Such large flood are extremely important events, not only in terms of human impact, but also from the standpoint of geomorphic effectiveness and geomorphic work. The Narmada and Tapi Rivers in central India are characterized by one of the most intense flood regimes in the seasonal tropics. Modern, historical and palaeoflood records indicate that large floods are relatively common hydrologic and geomorphic events on the Narmada and Tapi Rivers. A catastrophic flood on Tapi in July 1991, that occurred from heavy rains and a dam break, represents one of the highest unit discharges yet recorded in any part of central India. Flood competence studies indicate that the flood power of the two rivers is comparable with some of the largest historic and prehistoric floods reported from other parts of the world. The rivers have preserved geomorphic and sedimentologic records of palaeofloods for the last two millennium, and in Choral River a 5000 year old record has been located. Examination of the synoptic conditions associated with the flood generating low-pressure systems reveals that all but a few of them are the result of Bay of Bengal depressions. The flooding in such large rivers profoundly challenges flood-hazard management, because of limited instrumental records and large spatio-temporal variation. It is therefore imperative that the design engineering community in India incorporates the geomorphic, sedimentologic and botanic information in the planning and design of water resource development projects. © 1994.
- Komatsu, G., & Baker, V. R. (1994). Meander properties of Venusian channels. Geology, 22(1), 67-70.More infoAbstract: Venusian channels, which probably are lava channels, have meander properties that relate to their mode of formation. Their channel meanders probably formed in response to flow dynamics, as in the case of terrestrial rivers, but low sinuosity indicates less developed morphology. The meanders generally follow terrestrial river trends for wavelength (L) to width (W) ratios, suggesting an equilibrium adjustment of channel form. Slightly higher L/W, in comparison to terrestrial rivers, occurs for Venusian channel types other than sinuous rilles. The usually low L/W values for some Venusian and lunar sinuous rilles probably indicate modification of original meader patterns by erosional channel widening by lavas. The slightly larger radius of curvature to wavelength ratios of Venusian channels may be attributed to the short time during which the lavea channels formed, and/or they may represent a quasi-equilibrium state for the system. -from Authors
- Komatsu, G., & Baker, V. R. (1994). Plains Tectonism on Venus: Inferences from Canali Longitudinal Profiles. Icarus, 110(2), 275-286.More infoAbstract: Canali-type channels on Venus show inverted profile segments; that is, large portions of the channels trend uphill. The original gradients for these channels were not horizontal, but must have progressively trended downhill. Therefore, undulation patterns imposed on the profiles have to be the result of tectonism occurring since channel formation. This implies that some of the uppermost geological units of the plains, which are coincident with canali, experienced significant postemplacement tectonic deformation. The pattern of deformation is hierarchical. Within observational limits, at least two scales of deformation are indicated. The longer scale deformation (thousands of kilometers) corresponds to largescale basins; the shorter scale deformation (hundreds of kilometers) corresponds to ridge belts or to small-scale domes/basins. The latter features, at scales up to a few hundred kilometers, extensively deform some plains areas. Although not appearing in the topographic profiles because of resolution limitations, deformation scales of tens of kilometers or less, which mostly reflect wrinkle ridges, also overlap the longer deformation scales. The channels probably formed relatively quickly in comparison to the time scale of deformation. Canali formation is closely related to the genesis of plains, and canali profile deformation reflects tectonic processes operating at multiple scales. The lower limit rates of large-scale tectonic warping are comparable to epeirogenetic deformation rates for Earth's intraplate continental interiors. © 1994 Academic Press. All rights reserved.
- Martinez-Goytre, J., House, P. K., & Baker, V. R. (1994). Spatial variability of small-basin paleoflood magnitudes for a southeastern Arizona mountain range. Water Resources Research, 30(5), 1491-1501.More infoAbstract: Paleoflood reconstructions in eight watersheds for the largest floods in stable canyon reaches, showed there is a high correlation between drainage area and flood magnitude. It is also clear that basins located in the southern half of the Santa Catalina Mountains have larger unit discharges (peak discharge divided by drainage area) than those in the northern part of the range. The northern part of the range experiences a rain shadow effect that decreases the unit discharges generated in those basins. The unusually high unit discharge for one of the south facing basins is explained by its basin morphometry. Inverse problem solutions using a rainfall-runoff model demonstrate that both this basin and another with a comparable drainage area but a much lower estimated peak paleoflood discharge can have their peak flood outputs produced by the same storm intensity. The results demonstrate the potential of paleoflood data collection for understanding spatial variability in small basin flood hydrology. -from Authors
- Wohl, E. E., Fuertsch, S. J., & Baker, V. R. (1994). Sedimentary records of late Holocene floods along the Fitzroy and Margaret Rivers, Western Australia. Australian Journal of Earth Sciences, 41(3), 273-280.More infoAbstract: Slackwater sediments and palaeostage indicators record floods occurring prior to discharge gauging along the Fitzroy and Margaret Rivers. In upper Geikie Gorge along the Fitzroy River, preserved sequences record six floods ranging from 5000 to 30 000 m3 s-1 during the last 2000 years. Approximately 13 floods between 2000 and 20 000 m3s-1 are recorded in an unnamed gorge along the upper Margaret River during the last 4000 years. These floods are at the upper limit of world-wide discharge-drainage area curves. Conditions along the Fitzroy and Margaret Rivers are well-suited to preserving long, fairly accessible sedimentary flood records, in comparison to sedimentary records described from similar bedrock channels in the tropical regions of Queensland and the Northern Territory. The Fitzroy and Margaret River flood deposits indicate that, similar to other rivers with highly variable hydrologic regimes, the relatively short-term systematic gauge records from these basins may not adequately represent extreme discharges. -from Authors
- Wohl, E. E., Greenbaum, N., Schick, A. P., & Baker, V. R. (1994). Controls on bedrock channel incision along Nahal Paran, Israel. Earth Surface Processes & Landforms, 19(1), 1-13.More infoAbstract: Nahal Paran drains 3600 km2 of Egypt's Sinai peninsula and Israel's Negev Desert. Much of the channel is alluvial, but a canyon 10.5 km long has been incised into Late Cretaceous chert and dolomite in the lower portion of the basin. Slackwater deposits and paleostage indicators preserved within the canyon record approximately 10 floods of 200 to 2500 m3 s-1 over a period of at least 350 years. The greatest values of stream power occur along the lower half of the study reach, in association with three pronounced knickpoints and an inner channel. The presence of several similar, but buried and inactive, knickpoints along the upper study reach indicates that the locus of most active channel incision has shifted with time, probably in response to baselevel changes associated with tectonic activity along the Dead Sea Rift. Thus, the rate and manner of channel incision along the canyon of Nahal Paran are controlled by lithologic variability and tectonic uplift as they influence channel morphology and gradient, which in turn influence hydraulics and sediment transport. -from Authors
- Baker, V. (1993). Learning from the past. Nature, 361(6411), 402-403.
- Baker, V. R. (1993). Extraterrestrial geomorphology: science and philosophy of Earthlike planetary landscapes. Geomorphology, 7(1-3), 9-35.More infoAbstract: Newly discovered extraterrestrial landscapes afford an opportunity for adventitious change in the discipline of geomorphology. This opportunity contrasts with the various programs of stipulative change to the discipline initiated over the past century and leading to the present Systems-Process-Functional-Modeling (SPFM) paradigm among Anglo-American geomorphologists. Planetary geomorphology has been largely irrelevant to this paradigm and has found its home almost exclusively within geology. As exemplified by Grove Karl Gilbert's classic 1893 study of the moon's surface, planetary geomorphology affords a remarkable interplay of inference and observation in understanding nature. The balanced approach to scientific understanding, illustrated by Gilbert's work, has been lacking in some of the puzzle-solving exercises of modern SPFM geomorphology. Recent discoveries concerning Mars and Venus illustrate the role of extraterrestrial studies for enhancing the science of Earthlike planets and particularly Earth itself. © 1993.
- Baker, V. R., Benito, G., & Rudoy, A. N. (1993). Paleohydrology of late pleistocene superflooding, Altay Mountains, Siberia. Science, 259(5093), 348-350.More infoPMID: 17832349;Abstract: Cataclysmic flooding is a geomorphological process of planetary significance. Landforms of flood origin resulted from late Pleistocene ice-dammed lake failures in the Altay Mountains of south-central Siberia. Peak paleoflows, which exceeded 18 × 106 cubic meters per second, are comparable to the largest known terrestrial discharges of freshwater and show a hydrological scaling relation to floods generated by catastrophic dam failures. These seem to have been Earth's greatest floods, based on a variety of reconstructed paleohydraulic parameters.
- Ely, L. L., Enzel, Y., Baker, V. R., & Cayan, D. R. (1993). A 5000-year record of extreme floods and climate change in the Southwestern United States. Science, 262(5132), 410-412.More infoPMID: 17789949;Abstract: A 5000-year regional paleoflood chronology, based on flood deposits from 19 rivers in Arizona and Utah, reveals that the largest floods in the region cluster into distinct time intervals that coincide with periods of cool, moist climate and frequent El Niño events. The floods were most numerous from 4800 to 3600 years before present (B.P.), around 1000 years B.P., and after 500 years B.P., but decreased markedly from 3600 to 2200 and 800 to 600 years B.P. Analogous modern floods are associated with a specific set of anomalous atmospheric circulation conditions that were probably more prevalent during past flood epochs.
- Enzel, Y., Ely, L. L., House, P. K., Baker, V. R., & Webb, R. H. (1993). Paleoflood evidence for a natural upper bound to flood magnitudes in the Colorado River basin. Water Resources Research, 29(7), 2287-2297.More infoAbstract: Paleoflood data identify the maximum flood discharges that have occurred on individual rivers over the last several hundred to several thousand years. Even with this increase in the observational period, the largest paleoflood discharges do not exceed the upper bound of maximum peak discharges delineated by the envelope curve derived from the available gaged and historical records. This result accords with the hypothesis of an upper physical limit for flood magnitudes and suggests that, for the Colorado River basin, the upper limit can be approximated by existing systematic and historical data for large floods. Similar relationships also hold when paleofloods and gaged records are presented for the subregion of southern Arizona. -from Authors
- Kargel, J. S., Komatsu, G., Baker, V. R., & Strom, R. G. (1993). The Volcanology of Venera and VEGA Landing Sites and the Geochemistry of Venus. Icarus, 103(2), 253-275.More infoAbstract: Magellan images confirm volcanic interpretations of television panoramas and geochemical data obtained by Venera and VEGA landers. Magellan and Venera/VEGA data are consistent with mafic volcanic compositions at all seven landing sites, although such compositions were proven at only three sites. Rock analyses show an unexpectedly high fraction of potassium-rich lavas. If the seven Venera and VEGA samples are approximately representative of the upper crust, just 10 km of the average material distributed globally would contain as much potassium as contained in Earth's continental and oceanic crust. Despite the likelihood that Venus' crust is overwhelmingly mafic, in terms of highly incompatible elements it may represent the differentiated magmatic equivalent of Earth's granitoid continents and of the Moon's anorthositic highlands. Although associated tectonic and petrogenetic aspects of lunar and Venusian crustal genesis were different, crust-forming processes on both objects (and possibly early terrestrial continent formation) may have involved cataclysmic partial melting of large fractions of these planets' mantles. A fairly mafic alkaline character of Venus' crust is attributed to a generally anhydrous, carbonated composition of Venus' mantle, which contrasts with a generally uncarbonated and variably hydrated composition of Earth's mantle. Aside from this important difference, Venus' mantle is geochemically almost identical to Earth's and is distinct from all other planetary objects for which compositional data exist. The compositional similarity of the mantles of Venus and Earth implies that the combined geochemical effects of nebular condensation, planetary accretion, and core formation were not substantially different for these planets. © 1993 Academic Press. All rights reserved.
- Komatsu, G., Baker, V. R., Gulick, V. C., & Parker, T. J. (1993). Venusian Channels and Valleys: Distribution and Volcanological Implications. Icarus, 102(1), 1-25.More infoAbstract: Nearly complete image coverage of Venus by Magellan enabled us to map various venusian channel and valley landforms and to examine their associations with other geological units. Global mapping reveals a nonrandom distribution. The highest total concentration is in the equatorial regions, characterized by highlands, rift and fracture zones, and associated volcanic features. Many channels associated with flow deposits are similar to typical terrestrial lava drainage channels. They are observed to be associated with a wide range of volcanic edifices, such as coronae, shield volcanoes, and rift and fracture zones. One type of channel, similar morphologically to lunar sinuous rilles, is classified as a venusian sinuous rille. Based on the close associations of many venusian sinuous rilles with coronae, we hypothesize that mantle plume or blob volcanism has caused high effusion and sustained lava eruptions essential for sinuous rille formation. Mantle-derived, high-temperature, low-viscosity lava eruptions are responsible for the efficient erosional processes, particularly for thermal erosion that seems to be, at least partially, required for some sinuous rille formation. Many valley networks are observed in highlands and in association with coronae. Fracture systems and source zones for low-viscosity lavas, both key to network formation, were probably concentrated at highlands and coronae. Canali-type channels, which are morphologically unlike other known volcanic channels, are limited to certain plains regions. A wide range of low-viscosity lava types is possible for the channel-forming lava, depending on the formation mechanism. Their lengths exceed the lengths of other common volcanic channel types on Venus, implying a large volume of lava and long duration of the eruption. The close association of canali with plains regions implies that canali formation is probably related to the emplacement of plains. A hypothesized global resurfacing event late in Venusian history may be responsible for canali formation. © 1993 Academic Press. All rights reserved.
- Rudoy, A. N., & Baker, V. R. (1993). Sedimentary effects of cataclysmic late Pleistocene glacial outburst flooding, Altay Mountains, Siberia. Sedimentary Geology, 85(1-4), 53-62.More infoAbstract: Pleistocene glacial outburst floods were released from ice-dammed lakes of the Altay Mountains, south-central Siberia. The Kuray-Chuja lake system yielded peak floods in excess of 1 × 106 m3 s-1 and as great as 18 × 106 m3 s-1. The phenomenally high bed shear stresses and stream powers generated in these flows produced a main-channel, coarse-grained facies of coarse gravel in (1) foreset-bedded bars as much as 200 m high and several kilometers long, and (2) degradational, boulder-capped river terraces. Giant current ripples, 50 to 150 m in spacing, composed of pebble and cobble gravel, are locally abundant. The whole sedimentary assemblage is very similar to that of the Channeled Scabland, produced by the Pleistocene Missoula Floods of western North America. © 1993.
- Baker, V. R., Carr, M. H., Gulick, V. C., Williams, C. R., & Marley, M. S. (1992). Channels and valley networks. Mars, 493-522.More infoAbstract: Channels, valleys, and related features of aqueous origin on Mars are of profound importance in comparative planetology. Martian outflow channels formed by large-scale fluid outflow from subsurface sources. Elements of cataclysmic flooding, debris and ice flowage, as modified by volcanism and wind action, seem best to explain observed morphologies. Martian valley networks show their greatest similarity to terrestrial networks formed by sapping as water emanated from seeps and springs. -from Authors
- Baker, V. R., Komatsu, G., Parker, T. J., Gulick, V. C., Kargel, J. S., & Lewis, J. S. (1992). Channels and valleys on Venus: preliminary analysis of Magellan data. Journal of Geophysical Research, 97(E8), 13,421-13,444.More infoAbstract: A preliminary survey of Magellan imagery reveals more than 200 newly discovered relict channel and valley landform complexes. Simple channels include 1) sinuous rilles that closely resemble their lunar counterparts and 2) a newly recognized long sinuous form of high width-to-depth ratio and remarkably constant width. Herein designated canali, the most spectacular of these channels is 6800 km long. Streamlined hills and spill relationships at a cross-axial ridge are similar to features in flood channels. Venusian channels have a global distribution with most of the large canali-type channels developed on volcanic plains. Alternative hypotheses for the channel-forming processes include genesis by the following erosive fluids: ultramafic silicate melts, sulfur, and carbonate lavas. -from Authors
- Komatsu, G., Kargel, J. S., & Baker, V. R. (1992). Canali-type channels on venus: Some genetic constraints. Geophysical Research Letters, 19(13), 1415-1418.More infoAbstract: Canali-type channels on Venus are unique because of their great lengths (up to 6800 km) and nearly constant channel cross sectional shapes along their paths. A simple model incorporating channel flow and radiative cooling suggests that common terrestrial-type tholeiite lava cannot sustain a superheated and turbulent state for the long distances required for thermal erosion of canali within allowable discharge rates. If canali formed mainly by constructional processes, laminar tholeiitic flows of relatively high, sustained discharge rates might travel the observed distances, but the absence of levees would need to be explained. An exotic low temperature, low viscosity lava like carbonatite or sulfur seems to be required for the erosional genesis of canali.
- O'Connor, J., & Baker, V. R. (1992). Magnitudes and implications of peak discharges from glacial Lake Missoula. Geological Society of America Bulletin, 104(3), 267-279.More infoAbstract: New field evidence and discharge calculation procedures provide new estimates of maximum late Pleistocene glacial Lake Missoula Flood discharges for two important reaches along the flood route. Within the Spokane Valley, near the point of release, the peak discharge probably exceeded 17 ± 3 million m3.sec-1, the largest known terrestrial fresh-water flow. Consideration of these discharge values constrains model for the failure of glacial Lake Missoula. The maximum discharges estimated here are larger than theoretical and empirical predictions of maximum subglacial jokulhlaup-style releases for Lake Missoula. We postulate, consistent with geological relations in the glacial Lake Missoula basin and in the Channeled Scabland, that the largest late Wisconsinan Missoula Flood resulted from a cataclysmic falure of the impounding ice dam of glacial Lake Missoula. This large release may have been the result of a complete rupture of the ice dam. Subsequent multiple flows of lesser magnitude may have resulted from repeated subglacial releases from the lake. -from Authors
- Arvidson, R. E., Baker, V. R., Elachi, C., Saunders, R. S., & Wood, J. A. (1991). Magellan: Initial analysis of Venus surface modification. Science, 252(5003), 270-275.More infoPMID: 17769274;Abstract: Initial Magellan observations reveal a planet with high dielectric constant materials exposed preferentially in elevated regions with high slopes, ejecta deposits extending up to 1000 kilometers to the west of several impact craters, windblown deposits and features in areas where there are both obstacles and a source of particulate material, and evidence for slow, steady degradation by atmosphere-surface interactions and mass movements.
- Baker, V. R. (1991). A bright future for old flows. Temperate palaeohydrology, 497-520.More infoAbstract: The first part of this chapter briefly reviewed some of the methodology and results of recent fluvial palaeohydrological research. Judged within the framework of physical theory from other disciplines, it was an easy task to be critical. In contrast to certain trends in allied disciplines, the methodology in fluvial palaeohydrology is evolving in response to the nature of the system under investigation. For its continued health as a science, palaeohydrology should emphasis two goals: the development of accurate reconstructions of past hydrological conditions as a source of testing and verification of models for predicting hydrological change, and the discovery of the workings of important hydrological phenomena as elucidated by their operations in the past. -from Author
- Baker, V. R., & Twidale, C. R. (1991). The reenchantment of geomorphology. Geomorphology, 4(2), 73-100.More infoAbstract: Much of modern Geomorphology lacks the enchantment that the science possessed a century ago. Practical and philosophical impediments are thwarting modern attempts to achieve a satisfying understanding of landforms and their genesis. In recent years, even the security of geomorphologists' academic bases has been threatened within the cognate disciplines of Geography and Geology. During the 1960s these fields experienced so-called "scientific revolutions," which many geomorphologists either uncritically embraced or assumed to be irrelevant. While commendable in spirit, progressive initiatives to establish research traditions in landscape evolution, climatic geomorphology, and process studies all encountered fundamental limitations as unifying themes. More disturbing are ideological impositions that advocate geomorphological concentration on timeless, theoretical, or utilitarian problems. While facilitating precision of explanation and prediction, various geoideological bandwagons may stifle creativity, insight, and intellectual satisfaction. Most insidious is the substitution of elegantly structured methodology and theory for spontaneity, serendipity, and common sense. Hope for the reenchantment of Geomorphology lies in a new connectedness to nature that will facilitate the identification of anomalies and the formulation of outrageous hypotheses of causation. In the words of William Morris Davis, "...violence must be done to many of our accepted principles." Examples of such ideas may be found in fringe areas of the discipline, including planetary geomorphology, tectonic geomorphology, and denudation chronology with emphasis on ancient paleosurfaces. Geomorphologists should consider inverting their belief that they are achieving progressive (timebound) understanding of invariant (timeless) laws in nature. Rather, they may choose a geophysiological view in which the richness of natural history is revealed in a timeless conversation with the Earth. © 1991.
- Baker, V. R., Strom, R. G., Gulick, V. C., Kargel, J. S., Komatsu, G., & Kale, V. S. (1991). Ancient oceans, ice sheets and the hydrological cycle on Mars. Nature, 352(6336), 589-594.More infoAbstract: A variety of anomalous geomorphological features on Mars can be explained by a conceptual scheme involving episodic ocean and ice-sheet formation. The formation of valley networks early in Mars' history is evidence for a long-term hydrological cycle, which may have been associated with the existence of a persistent ocean. Cataclysmic flooding, triggered by extensive Tharsis volcanism, subsequently led to repeated ocean formation and then dissipation on the northern plains, and associated glaciation in the southern highlands until relatively late in martian history.
- Baker, V. R., Strom, R. G., Gulick, V. C., Kargel, J. S., Komatsu, G., & Kale, V. S. (1991). Erratum: Ancient oceans, ice sheets and the hydrological cycle on Mars (Nature (1991) 352 (589-594)). Nature, 354(6348), 86-87.
- Baker, V. R. (1990). Geological fluvial geomorphology. Special Paper of the Geological Society of America, 253, 21-31.More infoAbstract: The history of American fluvial geomorphology over the past century is viewed as one of conflict and crises. From 1888 to 1938, a controversy arose between (1) a rational approach to understanding landscape genesis and history, with its roots in geology, and (2) a spatial-analytical approach to landscape classification and description, with its roots in geography. By the 1960s, geomorphology, led by fluvial studies, had changed its emphasis from historical studies to process studies, and the geology/geography dispute became irrelevant. Since the 1960s, a new conflict has arisen between (1) problem-oriented studies of landform genesis and (2) method-oriented studies. The latter emphasize useful predictions and a methodology that generates respect from other scientific and engineering disciplines. In extreme cases, approach 2 may bypass the understanding of phenomena in order to generate useful predictions of systems assumed to embody the behavior of those phenomena. In order to achieve its goal of intellectually satisfying understanding of phenomena, approach 1 may require the stimulus of the occasional outrageous hypothesis, thereby posing a seeming anathema to an existing scientific program. The identification and explanation of anomalies is critical to approach 1. Because of the inherent conflict in these approaches to fluvial geomorphology, there is a need to balance opposing tendencies.
- Baker, V. R., Demsey, K. A., Ely, L. L., Fuller, J. E., House, P. K., O'Connor, J., Onken, J. A., Pearthree, P. A., & Vincent, K. R. (1990). Application of geological information to Arizona flood hazard assessment. Hydraulics/Hydrology of Arid Lands, 621-626.More infoAbstract: Hydrological modeling procedures applied to regulatory flood-hazard zonation can be misapplied when assumptions concerning flood-hazardous processes are violated. Geomorphological mapping of the Tortolita Mountain piedmont in southern Arizona reveals extensive high-standing nonhazardous inactive, relict Pleistocene fan surfaces within zones mapped by FEMA as subject to active alluvial fan processes and 100-year flooding. Paleoflood analysis of upstream mountain canyons documents that maximum flood discharges for the past century have been about 50% lower than the regulatory (100-year) flood discharges. Geological studies are essential complements to engineering models in order to generate public confidence that regulatory requirements derive from knowledge of real rather than idealized arid-region flood-hazard processes.
- Baker, V. R., Ely, L. L., & O'Connor, J. E. (1990). Paleoflood hydrology and design decision for high-risk projects. Hydraulic Engineering - Proceedings of the 1990 National Conference, 433-438.More infoAbstract: Paleoflood hydrology is not merely one of several alternative methods for risk-based design. Rather, certain kinds of accurate data on the largest paleofloods of recent millennia provide the independent means for testing either (a) flood-frequency analysis of conventional data, or (b) model-based flood parameters like the probable maximum flood. Unless it can be rationalized that such testing is unnecessary, then present flood design practice in the U.S. is subject to the accusation that it largely ignores a critical source of real-world information on precisely that phenomenon which it purports to wisely control: rare, high-hazard flooding.
- Baker, V. R., Kochel, R. C., Laity, J. E., & Howard, A. D. (1990). Spring sapping and valley network development. Special Paper of the Geological Society of America, 252, 235-265.
- Ely, L. L., & Baker, V. R. (1990). Large floods and climate change in the southwestern United States. Hydraulics/Hydrology of Arid Lands, 361-366.More infoAbstract: Floods can have a tremendous impact on water resources but their properties may fluctuate at frequencies that defy recognition in short-term instrumented records. Paleoflood deposits provide insight into this component of the hydrological system by preserving evidence of the largest discharges that have occurred on a given river over time periods that often exceed 1000 years. A regional paleoflood analysis currently in progress in the southwestern United States incorporates study sites on more than twenty rivers. Previous studies on rivers in central Arizona and southern Utah indicate periods of flooding around 800-1000 A.D., 1400-1600 A.D., the late 1800's and the present, separated by periods of relative quiescence. These consistent variations in the long-term flood series within a region suggest a hydroclimatic cause. As the paleoflood dataset from the Southwest becomes more complete, it will indicate variations in the spatial and temporal distributions of large floods in relation to past climatic conditions. The present flooding regime, while not particularly anomalous when viewed in the context of the entire paleoflood record, nevertheless does not contradict the possibility that we are moving into a period of climatic response to general global warming.
- Gulick, V. C., & Baker, V. R. (1990). Origin and evolution of valleys on Martian volcanoes. Journal of Geophysical Research, 95(B9), 14,325-14,344.More infoAbstract: Morphological analyses of six Martian volcanoes, Ceraunius Tholus, Hecates Tholus, Alba Patera, Hadriaca Patera, Apollinaris Patera, and Tyrrhena Patera, indicate that fluvial processes were the dominant influence in the initiation and subsequent development of many dissecting valleys. Lava processes and possibly volcanic density flows were also important as valley-forming processes. The presence of anomalously young fluvial valleys on Alba Patera indicates that fluvial valley activity did not entirely cease near the end of late heavy bombardment but rather persisted in isolated regions until mid to late Amazonian. -from Authors
- Gulick, V. C., & Baker, V. R. (1989). Fluvial valleys and martian palaeoclimates. Nature, 341(6242), 514-516.More infoAbstract: NETWORKS of small fluvial valleys are extensively developed throughout the ancient heavily cratered terrains of Mars. The existence of the valleys has been cited as compelling evidence for a relatively dense primordial atmosphere capable of maintaining an Earth-like hydrological cycle. Theoretical models of early atmospheric evolution describe the maintenance of a dense CO2 atmosphere and a warm, wet climate until the end of the heavy-bombardment phase of impacting. However, the presence of very young, Earth-like fluvial valleys on the northern flank of Alba Patera conflicts with this scenario. Whereas the widespread ancient martian valleys generally have morphologies indicative of sapping erosion by the slow outflow of subsurface water, the local Alba valleys were probably formed by surface-runoff processes. Because subsurface water flow might be maintained by hydro-thermal energy inputs and because surface-runoff valleys developed late in martian history, when planet-wide climatic conditions were presumably similar to the present, it is not necessary to invoke drastically different planet-wide climatic conditions to explain valley development on Mars. The Alba fluvial valleys can be explained by hydrothermal activity or outflow-channel discharges that locally modified the atmosphere inducing precipitation and local overland flow on low-permeability volcanic ash. © 1989 Nature Publishing Group.
- Baker, V. R. (1988). Cataclysmic processes in geomorphological systems. Zeitschrift fur Geomorphologie, Supplementband, 67, 25-32.More infoAbstract: The study of cataclysmic geomorphological processes is the basic science complement to the applied study of natural geomorphological hazards. Because of problems in field measurement, the scaling of experimental models, and the testing of theoretical simulations, cataclysmic geomorphological processes are probably best analyzed by event reconstruction. New developments in the mathematical modeling of geomorphological processes, geochronology, and the statistical treatment of geological data are converging to improve greatly the understanding of natural cataclysms and their effects on the landscapes. -from Author
- Baker, V. R. (1988). Flood erosion. Flood geomorphology, 81-95.More infoAbstract: Emphasizes the importance of resistance factors as well as dynamic ones in establishing the erosive effects of floods. Especially important is the distinction between alluvial channels and nonalluvial (resistant boundary) channels. -from Editors
- Baker, V. R. (1988). Flood geomorphology and palaeohydrology of bedrock rivers. Geomorphological studies in southern Africa. Proc. symposium, Transkei, 1988, 473-486.More infoAbstract: The emerging science of palaeoflood hydrology allows the accurate, quantitative reconstruction of flood histories in appropriate settings. Work in the Northern Territory, Australia, demonstrates the technique in tropical, savanna, and desert settings for rivers flowing through fold belts and plateau uplands. Numerous analogous settings in southern Africa afford excellent potential study sites. -from Author
- Baker, V. R. (1988). Geological fluvial geomorphology. Geological Society of America Bulletin, 100(8), 1157-1167.More infoAbstract: The history of American fluvial geomorphology over the past century is viewed as one of conflict and crises. Since the 1960s, a new conflict has arisen between 1) problem-oriented studies of landform genesis and 2) method-oriented studies. Because of the inherent conflict in these approaches of fluvial geomorphology, there is a need to balance opposing tendencies. -from Author
- Baker, V. R., & Kochel, R. C. (1988). Flood sedimentation in bedrock fluvial systems. Flood geomorphology, 123-137.More infoAbstract: Flood flows in such rivers produce phenomenally high flow velocity, shear stress, and stream power per unit area. Documents considerable field experience and observations of bedrock channel sedimentation in China, northern Australia, and the southwestern United States. In addition, recent flume experiments on the flood slackwater sedimentation are described. -from Editors
- Baker, V. R., Kochel, R. C., & Patton, P. C. (1988). Flood geomorphology. Flood geomorphology.More infoAbstract: Flood geomorphology is here considered to be the study of the role of floods in shaping the landscape, including the analysis of flood causes, flood processes, resistance factors to flood-induced landscape change, and changes in flood-related processes and forms through time. The 27 papers (abstracted separately) are arranged in sections: 1) external controls and geomorphic measurements; 2) flood erosional and depositional processes; 3) the interactions of floods, climate and landscapes; 4) paleofloods; 5) environmental management. -M.A.Bass
- Kochel, R. C., & Baker, V. R. (1988). Paleoflood analysis using slackwater deposits. Flood geomorphology, 357-376.More infoAbstract: The most accurate and detailed reconstructions of large paleofloods over long time periods are achieved in studies of certain stable-boundary fluvial reaches characterized by slackwater deposits and paleostage indicators (SWD-PSI). -from Editors
- Pickup, G., Allan, G., & Baker, V. R. (1988). History, palaeochannels and palaeofloods of the Finke River, central Australia. Fluvial geomorphology of Australia, 177-200.More infoAbstract: Summarises recent work in the Finke bedrock gorge, one of central Australia's larger and most spectacular river systems. The Finke has the best-explored slackwater deposit sequence on the continent. It therefore offers some insights on the magnitude and frequency of catastrophic floods and how they are expressed in the landscape. -from Authors
- Webb, R. H., O'Connor, J., & Baker, V. R. (1988). Paleohydrologic reconstruction of flood frequency on the Escalante River, south-central Utah. Flood geomorphology, 403-418.More infoAbstract: Typical of many streams in the arid or semi-arid western United States, Escalante River floods have heretofore been documented by a fragmentary, short-term systematic record. Here in contrast, historical data, tree ring data, and SWD-PSI data is given for as many as 20 paleofloods. Hydraulic flow modeling procedures are used to calculate paleoflood discharges. Of particular interest are the silt lines that are interpreted as precise paleostage indicators for ancient floods. Channel stability for bedrock reaches of the Escalante River is demonstrated with historic photographs. Of considerable importance for the Escalante River is the apparent clustering of flood events. Large floods occurred approximately 1000 years ago, about 500 years ago, and in historic times. The largest flows in the last 2000 years were comparable to the largest floods observed on similar-sized drainage basins in the region. -from Editors
- Baker, V. R. (1987). Paleoflood hydrology and design applications.. Array, Baton Rouge, U.S.A.: May 14-17, 1986, Dordrecht, The Netherlands, D. Reidel Publishing Co., 1987,.More infoAbstract: The use in China of historic flood records covering the last 2000 years is described. In the U.S.A., methods of using paleoflood data are not sufficiently well known. As an example of the usefulness of such methods, a project for the modification of a system of dams in Arizona is examined in the light of paleoflood data.
- Baker, V. R. (1987). Paleoflood hydrology and extraordinary flood events. Journal of Hydrology, 96(1-4), 79-99.More infoAbstract: Paleoflood hydrology is the study of past or ancient flood events. The most accurate technique involves the analysis of slackwater deposits and paleostage indicators (SWD-PSI). Slackwater deposits are sand and silt emplaced from suspension in exceptionally deep, high-velocity floods that characterize narrow, deep canyons in resistant geologic materials. These and other paleostage indicators are used to establish hydraulic grade lines for the generating flow events. Favorable sites for slackwater deposition include channel-margin areas where stresses and velocities are reduced below critical values necessary to maintain fine-grained bedload material (sand and silt) in suspension. Computerized procedures for hydraulic flow modeling are used to tie the elevations of the highest slackwater deposits to surveyed river cross sections. The flood discharges calculated by this method can be calibrated through the study of modern floods on gaged rivers. Correlation of multiple SWD-PSI sites along a river reach is used to identify the maximum paleostage achieved by a given flood. Advances in the dating of flood deposits permit estimates of flood frequency to be made extending over a data base of thousands of years. The major geochronologic tool is radiocarbon dating of various kinds of organic matter intercalated with the slackwater deposits. An important development is the use of the tandem accelerator mass spectrometer for direct measurement of 14C. Tiny blebs of charcoal, seeds and other organics can be analyzed in order to date ancient flood deposits of hydrologic significance. Since SWD-PSI studies yield very accurate determinations of paleoflood ages and magnitudes, there is a pressing need for new statistical procedures that make optimum use of the information content in paleoflood records for flood-frequency analysis. Nevertheless, SWD-PSI paleoflood hydrology has moved beyond the research phase; its use should be encouraged in evaluating past experience of extraordinary floods at appropriate hazardous sites. © 1987.
- Baker, V. R., & Costa, J. E. (1987). Flood power. Catastrophic flooding, 1-21.More infoAbstract: Channel boundary shear stress and stream power per unit boundary area are very useful concepts in assessing the role of rare, great floods in producing major geomorphic responses in fluvial systems. These variables were determined for the largest known flash floods in small drainage basins and for six historic dam-failure floods, predominantly in the United States. Even more powerful floods can be analyzed by paleohydraulic procedures. The Pleistocene Missoula floods and floods on the planet Mars approached ultimate limits of flood power defined by the onset on cavitation in fluvial flows. -from Authors
- Baker, V. R., & Pickup, G. (1987). Flood geomorphology of the Katherine Gorge, Northern Territory, Australia.. Geological Society of America Bulletin, 98(6), 635-646.More infoAbstract: Paleoflood hydrologic analysis of the deposits, employing step-backwater flow modeling, allows quantitative estimates to be made of geomorphologically significant flows.-from Authors
- Baker, V. R., Greeley, R., Komar, P. D., Swanson, D. A., & Waitt Jr, R. B. (1987). Columbia and Snake River Plains. Geomorphic systems of North America, 403-468.More infoAbstract: Sections here are 1) geomorphic evolution of the Columbia Plain and river; 2) the Spokane flood debate and its legacy; 3) cataclysmic flood processes and landforms; 4) the Snake River Plain. Volcanic features are compared with features on Mars. -K.Clayton
- Baker, V. R., Webb, R. H., & Pickup, G. (1987). Paleoflood hydrologic analysis at ungaged sites, central and northern Australia.. Array, Baton Rouge, U.S.A.: May 14-17, 1986, Dordrecht, The Netherlands, D. Reidel Publishing Co., 1987,.More infoAbstract: Paleohydrologic analyses were conducted in Katherine Gorge and upper Finke Gorge, Northern Territory, Australia. Maximum paleofloods were quantified and dated using carbon 14 methods. Further research on stacked flood slackwater depositional sequences is needed for the use of such data in flood frequency analysis.
- Partridge, J., & Baker, V. R. (1987). PALAEOFLOOD HYDROLOGY OF THE SALT RIVER, ARIZONA.. Earth Surface Processes and Landforms, 12(2), 109-125.More infoAbstract: Geomorphic evidence along bedrock-confined reaches of the Salt River in east-central Arizona provides a record of the river's largest flood events. Fine-grained flood slackwater deposits accumulated at channel margin irregularities several meters above the low-flow channel. Discharges associated with flow events responsible for the deposits were estimated by computer flowing modeling. These estimates document flood magnitudes in excess of gaged historic streamflows. A maximum discharge estimate of 4600 m**3 s**31**1 affixed to the flood scar represents the largest flood event in the record, and is given a minimum recurrence interval of 1000-2000 y. The 1952 flood is the largest historic flow event experienced along the study reach and is estimated at 2900 m**3 s**31**1. Two palaeoflood events preserved in the slackwater stratigraphy exceed the 1952 event, and are given recurrence intervals of 300 and 600 y. Discharge estimates affixed to these infrequent, large-magnitude flood events approach a maximum with decreased probabilities. This suggests that a physical limit on the discharge may exist within the Salt River drainage basin and is perhaps directly related to drainage basin size.
- Stedinger, J. R., & Baker, V. R. (1987). Surface water hydrology: historical and paleoflood information flood frequency analyses.. Reviews of Geophysics, 25(2), 119-124.More infoAbstract: Advances in the dating of paleofloods, and in methods for estimating paleoflood discharges, have had their greatest impact on a relatively new procedure: the analysis of slackwater deposit - paleostage indicators. Statistical procedures have also evolved that make better use of historical and paleoflood data in flood- frequency analyses. -from Author
- Webb, R. H., & Baker, V. R. (1987). Changes in hydrologic conditions related to large floods on the Escalante River, south-central Utah.. Array, Baton Rouge, U.S.A.: May 14-17, 1986, Dordrecht, The Netherlands, D. Reidel Publishing Co., 1987,.More infoAbstract: The history of flooding and consequent channel changes on the Escalante River in south central Utah are discussed. The consideration of paleohydrologic evidence of past major floods leads to the conclusion that a more robust test for non stationarity is needed for such rivers, particularly when using historical data in flood frequency analyses.
- O'Connor, J., Webb, R. H., & Baker, V. R. (1986). Paleohydrology of pool-and-riffle pattern development: Boulder Creek, Utah.. Geological Society of America Bulletin, 97(4), 410-420.More infoAbstract: Stratigraphic relationships and archaeologic and radiometric age constraints indicate that at least four large-magnitude, low-frequency flow events have occurred within the past 500 to 1000 radiocarbon years B.P.-from Authors
- Baker, V. R. (1985). Field trip: geomorphic surfaces in the Tucson Basin, Arizona.. Global mega-geomorphology. Proc. workshop, Oracle, AZ 1985, 121-122.More infoAbstract: Describes a one-day field trip designed to view prominent geomorphic features which can be seen on Landsat Thematic Mapper images. -K.Clayton
- Baker, V. R. (1985). Models of fluvial activity on Mars.. Models in geomorphology. Binghamton symposia in geomorphology: international series 14, 287-312.More infoAbstract: Improved images from the Viking missions reveal many features, including large-scale sinuous channels, streamlined forms and evidence of ponding. Rejecting other agents of erosion, Baker concludes that these features can only be explained by a model that invokes vast quantities of flowing water. Ice-rich permafrost is considered to be the source of the water. Valley networks are morphometrically similar to terrestrial and simulated sapping networks.-from Editor
- Baker, V. R. (1985). Relief form on planets.. Themes in geomorphology, 245-259.More infoAbstract: Exemplifies the classic 'comparative method' of geography, as the study of planetary surfaces relies on analogic reasoning; equally, some planetary surfaces contain excellent analogues for little-understood terrestrial processes. Thus, the study of relief forms on other planets is a natural extension of the science of landforms on our own planet.-from Editor
- Baker, V. R., & Bunker, R. C. (1985). Cataclysmic Late pleistocene flooding from glacial Lake Missoula: A review. Quaternary Science Reviews, 4(1), 1-41.More infoAbstract: Late Wisconsin floods from glacial Lake Missoula occurred between approximately 16 and 12 ka BP. Many floods occurred; some were demonstrably cataclysmic. Early studies of Missoula flooding centered on the anomalous physiography of the Channeled Scabland, which J. Harlen Bretz hypothesized in 1923 to have developed during a debacle that he named 'The Spokane Flood'. Among the ironies in the controversy over this hypothesis was a mistaken view of uniformitarianism held by Bretz's adversaries. After resolution of the scabland's origin by cataclysmic outburst flooding from glacial Lake Missoula, research since 1960 emphasized details of flood magnitudes, frequency, routing and number. Studies of flood hydraulics and other physical parameters need to utilize modern computerized procedures for flow modeling, lake-burst simulation, and sediment-transport analysis. Preliminary simulation models indicate the probability of multiple Late Wisconsin jökulhlaups from Lake Missoula, although these models predict a wide range of flood magnitudes. Major advances have been made in the study of low-energy, rhythmically bedded sediments that accumulated in flood slack-water areas. The 'forty floods' hypothesis postulates that each rhythmite represents the deposition in such slack-water areas of separate, distinct cataclysmic floods that can be traced from Lake Missoula to the vicinity of Portland, Oregon. However, the hypothesis has numerous unsubstantiated implications concerning flood magnitudes, sources, routing and sedimentation dynamics. There were multiple great Late Wisconsin floods in the Columbia River system of the northwestern United States. Studies of high-energy, high altitude flood deposits are necessary to evaluate the magnitudes of these floods. Improved geochronologic studies throughout the immense region impacted by the flooding will be required to properly evaluate flood frequency. The cataclysmic flood concept championed by J. Harlen Bretz continues to stimulate exciting and controversial research. © 1985.
- Baker, V. R., & III, J. H. (1985). Global megageomorphology: workshop summary, conclusions and recommendations.. Global mega-geomorphology. Proc. workshop, Oracle, AZ, 1985, l13-120.More infoAbstract: Remote sensing has provided an exciting new technique to geomorphology and deserves exploitation at the global scale. It allows the chance to 'think big'. The summary includes recommendations for implementation. -K.Clayton
- Baker, V. R., Pickup, G., & Polach, H. A. (1985). Radiocarbon dating of flood events, Katherine Gorge, Northern Territory, Australia.. Geology, 13(5), 344-347.More infoAbstract: Radiocarbon analyses of organic materials provide accurate dating of flood events in the Katherine Gorge, Northern Territory, Australia. Selected flood events in the period 1955-1980 can be very precisely dated, essentially to the calendar year, through the use of curves showing the time variation of anomalously high 14C activity in the troposphere that was generated by nuclear testing. Conventional radiocarbon analysis of alluvial charcoal and organic litter is used to establish dates for the largest Katherine River floods of the past several centuries. The improved geochronologic techniques demonstrated here will help improve paleoflood hydrologic interpretations. -Authors Dept. of Geosciences, Univ. of Arizona, Tuczon, Arizona 85721, USA. English
- Brakenridge, G. R., Newsom, H. E., & Baker, V. R. (1985). Ancient hot springs on Mars: Origins and paleoenvironmental significance of small Martian valleys. Geology, 13(12), 859-862.More infoAbstract: At least two classes of small valleys (subparallel slope ravines and flat-floored branching valleys) shown on Viking imagery of Mars exhibit spatial relationships to impact structures. Cessation of their formation at the terminus of the heavy bombardment period, about 3.8 Ga, also implies a causal relationship between valley formation and cratering. We hypothesize that these valley types originated through the interaction of ground ice and hot springs located along the permeable fringes of slowly cooling impact melts. The valleys grew by a combination of headward sapping and down-valley water and ice fluid flow. The probable widespread operation of impact-related hydrothermal systems early in Mars history indicates that it is not necessary to infer atmospheric changes to explain valley origin. © 1985 Geological Society of America.
- Ely, L. L., & Baker, V. R. (1985). Reconstructing paleoflood hydrology with slackwater deposits: Verde River, Arizona.. Physical Geography, 6(2), 103-126.More infoAbstract: Fine-grained slackwater flood deposits provide a key to the paleoflood history of the Verde River in central Arizona. During large flows, the slackwater deposits accumulate in areas of sharply reduced flow velocity at channel expansions and contractions or in back-flooded tributaries. The upper surfaces of the highest deposits approximate the peak stages of the associated floods. Stratigraphic analysis, radiocarbon and archaeological dating, and correlation between slackwater sites along the study reach revealed multiple floods, including two paleofloods that pre-date the 80-year observational record of flows on the Verde River. Discharges calculated with the HEC-2 computer flow model extended the record of rare flood events by 1000 years. The largest flow in that time period measured only 5000-5400 cms, which supports the contention of an upper limit on the maximum flood that can be reasonably expected. Revised recurrence intervals based on the extended paleoflood record were used as a basis to compare various methods of flood frequency analysis. A combination of the log-Pearson Type III distribution for recurrence intervals up to 100 years, and a regional envelope curve for less frequent flow events, produced a frequency curve that coincided with both the modern and paleoflood discharges.-Authors
- Baker, V. R. (1984). Planetary geomorphology.. Journal of Geological Education, 32(4), 236-246.More infoAbstract: Images of planetary surfaces returned by the Mariner, Viking, and Voyager spacecraft show landforms that can only be understood by careful comparison to terrestrial analogs. This has resulted in renewed interest in terrestrial impact craters, large-scale volcanism, eolian erosion, cataclysmic landslides, debris flows, relict landforms, flood channels, and erosion surfaces. Geomorphic processes and the resulting landforms must be evaluated for various gravitational, atmospheric, tectonic, and temporal constraints. -from Author
- Baker, V. R. (1983). Late-Pleistocene fluvial systems.. Late-Quaternary environments of the United States. Vol. 1, 115-129.More infoAbstract: Classical models of river incision and aggradation are much too simple for universal application. Although detailed fluvial chronologies may be usefully developed in some local settings, regional correlation requires great caution. River metamorphosis, especially underfitness, was widely achieved during the late Pleistocene. However, this phenomenon involved the adjustment of multiple variables in addition to stream flow. Large-scale flooding was locally important around the many ice margins during the late Pleistocene. In the northwestern United States, catastrophic flooding played a dominant role in the development of landscapes such as the Channeled Scabland. -from Author
- Baker, V. R. (1983). PALEOFLOOD HYDROLOGIC TECHNIQUES FOR THE EXTENSION OF STREAMFLOW RECORDS.. Transportation Research Record, 18-23.More infoAbstract: Paleoflood hydrology includes geomorphic-botanic studies of the effects of ancient floods on the landscape and the study of ancient slack-water deposits. Slack-water deposits consist of sand and silt that accumulated relatively rapidly from suspension during major floods. Useful slack-water sediment accumulations occur along bedrock canyons at the mouths of tributaries and at other protected localities. Where individual flood-sedimentation units can be recognized, various dating techniques are used to assign ages to the responsible flood events. Problems with incomplete flood records at any one slack-water site, the relating of deposit heights to paleoflood stages, and the age relationships of dated materials to flood ages require the analysis and correlation of numerous sites and flood layers along a given river reach. Paleostage determinations and flood ages can be converted to discharge and recurrence-interval estimates for the large, rare floods recorded in a slack-water sequence.
- Baker, V. R. (1983). Paleoflood hydrologic analysis from slack-water deposits.. Quaternary Studies in Poland, 4, 19-26.More infoAbstract: Slack-water sedimentation analysis has been successfully applied to the paleohydrologic interpretation of the late Pleistocene Missoula floods (13 000 14C yr BP in the northwestern US). It is especially useful in Holocene studies, as demonstrated by work in semi-arid regions (Texas, Utah, northern Australia) and humid temperate regions (Connecticut, Virginia, Pennsylvania). -from Author
- Baker, V. R., Boothroyd, J. C., Carr, M. H., Cutts, J. A., Komar, P. D., Laity, J. E., Pieri, D., Thompson, D. E., Lucchitta, B. K., Masursky, H., Malin, M. C., Nummedal, D., & Patton, P. C. (1983). Channels and valleys on Mars. Bulletin of the Geological Society of America, 94(9), 1035-1054.More infoAbstract: The discovery of channels, valleys, and related features of aqueous origin on Mars is of profound importance in comparative planetology. Models of the evolution of planetary surfaces and atmospheres must be reconciled with the diversity, abundance, and origins of channels and valleys on Mars. The term "channel" is properly restricted to those Martian troughs that display at least some evidence of large-scale fluid flow on their floors. Outflow channels show evidence of flows emanating from zones of chaotic terrain. The term "valley" applies to those elongate Martian troughs, or systems of troughs, that also appear to have formed by fluid flow, but which lack a suite of bed forms on their floors. The Martian valleys of greatest interest consist of interconnected, digitate networks that dissect extensive areas of heavily cratered uplands on the planet. The diversity of Martian channels and valleys is nearly as great as that of their terrestrial counterparts. Even though polygenetic and highly modified features abound, water was a necessary ingredient in the various channel- and valley-forming processes. The outflow channels involved large-scale fluid flow, entailing as yet unresolved percentages of liquid and solid phases, entrained sediment, and debris flowage. The formation of valley networks required ground water or ground ice, contributing to sapping and various other hillslope phenomena. Channels and valley networks probably require an ancient epoch with surface temperatures and pressures higher than at present. The aqueous formation of channels is release-limited, requiring short-duration floods of immense volumes. The origin of valley networks is perseverance-limited, requiring the maintenance of prolonged seepage and surface flow. Both phenomena are consistent with a thick, ice-rich Martian permafrost formed either during a volatile-rich early epoch or by very effective recycling of planetary water. © 1983 Geological Society of America.
- Baker, V. R., Kochel, R. C., Patton, P. C., & Pickup, G. (1983). Palaeohydrologic analysis of Holocene flood slack-water sediments.. Modern and ancient fluvial systems, 229-239.More infoAbstract: Estimates of the frequency and discharge of large floods can be refined and extended over the past 10 000 years through the study of slack-water sediments deposited in bedrock canyons and gorges. Slack-water deposits are typically fine-grained sand and silt that accumulate during major floods in protected areas where current velocity is reduced, such as in back-flooded tributary mouths, at channel expansions, and downstream from bedrock spurs. Relatively narrow bedrock canyons in arid, savanna, and semi-arid regions provide excellent areas for estimating flood discharges from the elevation of slack-water deposits. The accumulation and preservation of slack-water sediment sequences appear to be controlled by tributary-mainstream junction morphology and by tributary drainage basin efficiency. -from Authors
- Baker, V. R., Kochel, R. C., Patton, P. C., & Pickup, G. (1983). Palaeohydrologic analysis of Holocene flood slack-water sediments.. Special Publication - International Association of Sedimentologists,, 6, 229-239.More infoAbstract: Relatively narrow bedrock canyons in arid, savanna, and semi-arid regions provide excellent areas for estimating flood discharges from the elevation of slack-water deposits because: 1) relatively small discharge increases are accompanied by large increases in river stage, 2) the bedrock canyons provide stable cross-sections for slope-area calculations, and 3) the paucity of vegetation limits sediment bioturbation. Along the lower Pecos River of western Texas the slack-water sediment stratigraphies record between six and ten major flood events. This record extends back at least 2000 years in some canyons, and as far as 10 000 years at the Arenosa Shelter site. In this region we have been able to apply geological data to extend observational records of major floods to achieve flood-frequency curves over a time base in millennia, rather than in decades. The procedure allows for the realistic assessment of recurrence intervals for large-magnitude events. -from Authors
- Baker, V. R., Pickup, G., & Polach, H. A. (1983). Desert palaeofloods in central Australia. Nature, 301(5900), 502-504.More infoAbstract: Hydrological conditions in arid regions are notoriously difficult to characterize in time and space. The inherent variability of rainfall and the resulting runoff poses problems for both economic development and palaeoenvironntental studies. Quantitative data on past floods are especially useful because the extreme rainfalls that generate desert floods are important environmental determinants in the world's arid environments. Unfortunately these are the environments that lack long-term hydrological records. We report here on the application of a palaeohydrological procedure1,2 that utilizes flood sediments as palaeostage indicators. By determining the ages of the responsible palaeofloods it is possible to evaluate their frequency of occurrence. The magnitude and frequency of floods on major desert stream or wadi systems provide critical palaeoclimatic information by delimiting areal and temporal shifts in rainfall-inducing weather systems. Central Australia is an ideal region in which to illustrate this technique because major phases of flooding correspond to the increased extratropical influence of the north Australia monsoons and/or tropical cyclones. We demonstrate here the use of palaeoflood hydrology to evaluate the recent phase of immense floods on the Finite River near Alice Springs in arid central Australia. The method approximates the magnitudes of the three great floods of 1967, 1972 and 1974, and it proves to be useful in other desert regions where conventional hydrological information is lacking. © 1983 Nature Publishing Group.
- Kochel, R. C., & Baker, V. R. (1982). Paleoflood hydrology. Science, 215(4531), 353-361.More infoAbstract: The difficult task of estimating recurrence intervals for large floods has long plagued hydrologists because statistical measures fail when return intervals of floods exceed the length of historical data sets. Sediments deposited in the backwaters of large floods may accumulate thick sequences in tributary mouths. Stratigraphic and sedimentologic studies of these sequences combined with radiocarbon dating have established a 10,000-year paleoflood record for the lower Pecos and Devils rivers in southwestern Texas. This technique is rapid and relatively inexpensive and can be used where historical records are short or entirely absent.
- Kochel, R., Baker, V., & Patton, P. C. (1982). PALEOHYDROLOGY OF SOUTHWESTERN TEXAS.. Water Resources Research, 18(4), 1165-1183.More infoAbstract: The paper presents a review of the literature that deals with the paleoflood discharge and frequency estimates which are extended over 10,000 years by the study of slack-water flood sediments. Morphostratigraphic approach that combines recorded data with geomorphic evidence to derive estimates of flood frequency is discussed. This technique offers an inexpensive and rapid way to assess catastrophic flood risk.
- Patton, P. C., Baker, V. R., & Kochel, R. C. (1982). Slack-water deposits: a geomorphic technique for the interpretation of fluvial paleohydrology.. Adjustments of the fluvial system. Proc. 10th geomorphology symposium, Binghamton, 1979, 225-254.More infoAbstract: During large floods overbank sedimentation is greatest in slack-water areas associated with channel expansions and the mouths of tributaries which are either back-flooded or hydraulically dammed. Slack-water deposits in eastern Washington and central and west Texas provide information on the magnitude, frequency and areal extent of past floods. The paleohydrologic record derived from studies of slack-water alluvial stratigraphy is useful in assessing the rates of geomorphic change in river channels that result from infrequent processes that cannot be measured directly.-from Authors
- Baker, V. R. (1981). The geomorphology of Mars.. Progress in Physical Geography, 5(4), 473-513.More infoAbstract: The Martian environment is best described as an exceedingly cold dry desert. Features discussed include impact craters, volcanic and structural landforms, weathering and aeolian features, hillslopes and mass movement, periglacial and permafrost features, polar terrains and glaciation, and channels and valleys.-K.Clayton
- Baker, V. R. (1980). A preliminary assessment of the fluid erosional processes that shaped the Martian outflow channels.. Proceedings, 9th Lunar & Planetary Science Conference 1978, (Pergamon Press, New York), 3205-3223.More infoAbstract: Whatever process is invoked to explain the Martian outflow channels must also explain a distinctive assemblage of channel landforms: regional and local anastomosing patterns, expanding and contracting reaches associated with flow constrictions, streamlined uplands, inner channels with recessional headcuts, pendant forms (bars or erosional residuals) on the downcurrent sides of low obstacles, longitudinal grooves, irregular 'etched' zones on channel floors, and scour marks around obstacles. -from Author
- Baker, V. R., & Kochel, R. C. (1980). Morphological mapping of Martian outflow channels.. Proceedings, 9th Lunar & Planetary Science Conference (1978), (Pergamon Press, New York), 3181-3192.More infoAbstract: Geomorphic mapping of selected portions of Martian outflow channels was performed in order to facilitate comparisons to terrestrial landforms. We interpret the maps to illustrate a correspondence between Martian channel features and terrestrial landforms developed by catastrophic flood erosion in the Channeled Scabland. The following features all occur in remarkably similar arrangements on the flood-channel floors of both planets: streamlined uplands, longitudinal grooves, scour marks, inner channel cataracts, etched zones, and possible pendant bars. - Authors
- Baker, V. R., & Kochel, R. C. (1980). Morphometry of streamlined forms in terrestrial and Martian channels.. Proceedings, 9th Lunar & Planetary Science Conference 1978, (Pergamon Press, New York), 3193-3203.More infoAbstract: Although the forms on both planets are not identical, they are similar enough to have been produced by similar processes. Relationships of width vs. length, length vs. area, and width vs. area suggest that the forms have developed an ideal shape, elongated sufficiently to reduce pressure drag in the responsible fluid, but not so long that they created excessive skin resistance. -from Authors
- Baker, V. R., Kochel, R. C., & Patton, P. C. (1979). Long-term flood frequency analysis using geological data ( Pecos River Texas).. The hydrology of areas of low precipitation. Proc. Canberra symposium, December 1979, (International Association of Hydrological Sciences, Washington DC; IAHS-AISH Publication 128), 3-9.More infoAbstract: A geological approach to palaeoflood analysis is demonstrated. The most useful data for geological flood frequency analysis come from confined bedrock canyons in which relatively small discharge variations produce relatively large changes in stage. The Lower Pecos River of western Texas contains several sites with correlative slack-water sequences for 10-12 major flood events. The data show that the Pecos flood of 1954, which was nearly an order of magnitude larger than any other in 40 years of record, had a recurrence interval of 2000+ years.- from Authors
- Holz, R. K., Baker, V. R., Sutton Jr, S. M., & Penteado-Orellana, M. (1979). South American river morphology and hydrology.. Apollo-Soyuz Test Project, Vol 2: earth observations and photography, 545-594.More infoAbstract: A guide to the hydrologic properties of streams in the Amazon and Paraguay Basins is presented. Photographs are presented from the Apollo Soyuz Test Project of the Amazon Basin. Stream regimes, including analyses of meander wavelengths, flood plain development, and basin morphology are discussed. Adjustments of changes in river morphology caused by altered water and sediment discharges and by Quaternary climatic changes are discussed. -from STAR, 18(1), 1980
- Baker, V. R. (1978). The spokane flood controversy and the martian outflow channels. Science, 202(4374), 1249-1256.More infoAbstract: In a series of papers published between 1923 and 1932, J Harlen Bretz described an enormous plexus of proglacial stream channels eroded into the loess and basalt of the Columbia Plateau, eastern Washington. He argued that this region, which he called the Channeled Scabland, was the product of a cataclysmic flood, which he called the Spokane flood. Considering the nature and vehemence of the opposition to his hypothesis, which was considered outrageous, its eventual scientific verification constitutes one of the most fascinating episodes in the history of modern science. The discovery of probable catastrophic flood channels on Mars has given new relevance to Bretz's insights. Copyright ©1978 AAAS.
- Patton, P. C., & Baker, V. R. (1978). New evidence for pre-Wisconsin flooding in the channeled scabland of eastern Washington. Geology, 6(9), 567-571.More infoAbstract: Flood-gravel deposits capped by loess sequences that display well-developed argillic, calcic, and petrocalcic paleosols indicate pre-Wisconsin catastrophic flooding in the Cheney-Palouse tract of the channeled scabland, eastern Washington. The most complete stratigraphic exposure reveals two flood-gravel units, one of pre-Wisconsin age and the other representing the last major phase of scabland flooding (late Wisconsin). The two gravel units are separated by three loess units. Each period of loess deposition was followed by a soil-forming interval. The older of the two flood-gravel units contains cobbles of an early pre-Palouse Formation (that is, pre-Bull Lake) loess. It is capped by a loess unit displaying superimposed argillic and petrocalcic soil horizons. Above the petrocalcic horizon are two younger layers of loess (the Palouse Formation), each of which displays a paleosol having a weakly developed argillic B horizon and a calcic C horizon. These units are overlain by gravel from the last major phase of scabland flooding, which is, in turn, overlain by late Wisconsin and Holocene loess. The earliest flood probably carved part of the Cheney-Palouse scabland morphology during a glaciation prior to that responsible for the Palouse Formation. © 1978 Geological Society of America.
- Baker, V. R. (1977). Stream-channel response to floods, with examples from central Texas. Bulletin of the Geological Society of America, 88(8), 1057-1071.More infoAbstract: The principle that most geomorphic work is accomplished by relatively frequent events of moderate intensity requires modification for application to stream channels in certain climatic and physiographic settings. Small drainage basins in regions of highly variable flood magnitudes appear to have a high potential for catastrophic response. Flash-flood potential for small basins can be regionally mapped by computing the standard deviation of the logarithms of the annual flood peaks. Highly right-skewed flood-frequency distributions indicate that a high potential exists in certain arid regions of the southwestern United States and in the seasonal subtropical-to-steppe climate region of central Texas. High-magnitude flood response is also promoted by physiographic factors, such as hillslope morphology, soils, rock type, and drainage density. The relative importance of overland flow, which produces intense flood peaks, versus interflow and ground-water flow, which produce more uniform streamflow, appears to integrate both the climatic and the physiographic influences on the potential for catastrophic floods. Another factor in realizing the climatic-hydrologic potential for catastrophic stream-channel response is the resistance of the channel itself to scour. Small limestone streams in central Texas show significant channel modification only during the rare high-magnitude floods characteristic of that region. This is mainly because of the high response threshold required to scour bouldery alluvium and dense valley-bottom vegetation. Effects of especially intense floods on such streams include the following: entrainment of jointed bed rock and boulders as much as 3 m in diameter, uprooting of trees that usually bind coarse-grained point bars, macroturbulent transport of boulders even over divides into adjacent drainages, local scour of chutes on meander bends, and passive boulder deposition on other preflood valley-bottom surfaces. © 1977 Geological Society of America.
- Patton, P. C., & Baker, V. R. (1977). Geomorphic response of central Texas stream channels to catastrophic rainfall and runoff.. Geomorphology in arid regions. Proc. 8th Binghamton symposium in geomorphology, 1977, 189-217.More infoAbstract: In central Texas the morphology of the streams incised into the Cretaceous limestone bedrock of the Edwards Plateau is controlled by catastrophic floods. This is partly a response to a climatic regime which has produced near record intensity rainfalls of up to 24 hours duration. Flooding on two small streams in 1972, resulting from 406mm of rainfall in four hours, produced spectacular erosion and transport of limestone bedrock. Radiocarbon dates of buried floodplain sediments indicate a minimum recurrence interval of 400 yr for geomorphically significant flooding of these streams. -from Authors Author's address(es) ) Dept. of Earth and Environmental Sciences, Wesleyan Univ., USA. ) Dept of Geological Sciences, Univ. of Texas at Austin, USA.
- Baker, V. R. (1976). Hydrogeomorphic methods for the regional evaluation of flood hazards. Environmental Geology, 1(5), 261-281.More infoAbstract: The "upstream" approach to flood hazard evaluation involves the estimation of hydrologic response in small drainage basins. This study demonstrates the application of geomorphology to such studies in a region of unusually intense flooding in central Texas. One approach to flood hazard evaluation in this area is a parametric model relating flood hydrograph characteristics to quantitative geomorphic properties of the drainage basins. A preliminary model uses multiple regression techniques to predict potential peak flood discharge from basin magnitude, drainage density, and ruggedness number. After mapping small catchment networks (4 to 20 km2) from remote sensing imagery, input data for the model are generated by network digitization and analysis by a computer-assisted routine of watershed analysis. The study evaluated the network resolution capabilities of the following data formats: (1) large-scale (1:24,000) topographic maps, employing Strahler's "method of v's", (2) low altitude black-and-white aerial photography (1:13,000 and 1:20,000 scales), (3) NASA-generated aerial infrared photography at scales ranging from 1:48,000 to 1:123,000, and (4) Skylab Earth Resources Experiment Package S-190A and S-190B sensors (1:750,000 and 1:500,000 respectively). Measured as the number of first order streams or as the total channel length identified in small drainage areas, resolution is strongly dependent on basin relief. High-density basins on the Edwards Plateau were poorly depicted on orbital imagery. However, the orbital network definition of low-relief basins on the inner Texas Coastal Plain is nearly as accurate as results from large-scale topographic maps. Geomorphic methods are also useful for flood hazard zonation in "downstream" flood plain areas. Studies of the Colorado River valley near Austin, Texas, easily distinguished infrequent (100- to 500-year recurrence interval), intermediate (10- to 30-year), and frequent (1- to 4-year) hazard zones. These mapping techniques are especially applicable to the rapid regional evaluation of flood hazards in areas for which there is a lack of time and money to generate more accurate engineering-hydraulic flood hazard maps. © 1976 Springer-Verlag New York Inc.
- Patton, P. C., & Baker, V. R. (1976). MORPHOMETRY AND FLOODS IN SMALL DRAINAGE BASINS SUBJECT TO DIVERSE HYDROGEOMORPHIC CONTROLS.. Water Resources Research, 12(5), 941-952.More infoAbstract: Field surveys of a high-density limestone basin in central Texas show that 1:24,000 scale topographic maps accurately portray the efficient stream channel system but fail to reveal numerous small gullies that may form portions of hillslope hydrologic systems. Flood potential in drainage basins can be defined by a regional index computed as the standard deviations of the logarithms of the annual maximum streamflows. Transient controls on flood response, such as differences between local rainstorm intensities, appear to be the major influences on hydrographs in areas of moderate dissection and relief.
- Baker, V. R. (1975). Urban geology of boulder, colorado: A progress report. Environmental Geology, 1(2), 75-88.More infoAbstract: A cooperative program in urban geology between the city of Boulder, Colorado, and the Department of Geological Sciences, University of Colorado, has been in effect since late 1969. The principal geological problems in the rapidly growing urban environment of Boulder include: 1. Swelling clays in the Pierre Shale have been related to foundation failure, pavement heaving, and landsliding on hillslopes. 2. Colluvium and ancient landslides have been made unstable by removal of support, by loading with buildings or fill, and by increases over natural moisture contents through lawn watering and septic-tank seepage. 3. Flooding on high-gradient mountain streams has been caused by sedimentation induced by the constriction of natural channels through urban development. In May, 1969, Bear Canyon Creek overflowed its banks with a discharge of less than one-fifth its design capacity. Flooding was caused by coarse bedload deposited upstream from a culvert. The Boulder city geologist collects data on soils exposed in open excavations within the city, maps ancient and modern landslides, provides information for contractors bidding on public works projects, and reviews the geologic aspects of all consulting work prepared for the city. Examples of formats used for the communication of information to responsible city officials include geotechnic maps of all open cuts, street pavement design maps, and input into the city-wide standard specifications for enginnering projects. © 1975 Springer-Verlag New York Inc.
- Baker, V. R., & Ritter, D. F. (1975). Competence of rivers to transport coarse bedload material. Bulletin of the Geological Society of America, 86(7), 975-978.More infoAbstract: Shear-stress analyses provide easily determined estimates of the competence of rivers to transport coarse bedload material. Relevant data from diverse geological and engineering reports are integrated, and a good correlation between competent particle size and shear stress results when data points are derived in a uniform way. Because flow mechanics differ in contrasting fluvial environments, the shear stresses needed to entrain large sediment may diverge considerably from values based on theoretical grounds. In shallow rivers, entrainment may occur at lower shear stresses than predicted by the Shields theory because hydrodynamic lift and bank caving provide additional transporting force. In very deep flows, the shear stresses needed to initiate particle movement are greater than theoretical values. Potential use of the empirical relationship between particle size and shear stress is limited by the following considerations: (1) random nature of turbulent life forces, (2) problems in interpreting the significance of the sedimentary deposit, (3) sediment finer than 5 cm in diameter is not considered, and (4) the analysis ignores special considerations of sediment packing, shape, and grain-size distributions. © 1975 Geological Society of America.
- Baker, V. R. (1974). Paleohydraulic interpretation of Quaternary alluvium near Golden, Colorado. Quaternary Research, 4(1), 94-112.More infoAbstract: Quaternary terraces and pediments along Ralston Creek and Clear Creek, near Golden, Colorado, are associated with Verdos, Slocum, Louviers, and Broadway Alluviums. Terrace deposits can be locally correlated on the basis of elevation and relict paleosols. The terrace sediments probably represent aggradation by braided streams flowing from glaciated drainage basins. Engineering hydraulic calculation procedures suggest that flood flows were 2-3 m deep on steep gradients (0.008-0.01). Discharges were as great as 1400 m3/sec, nearly an order of magnitude greater than modern flood discharges. The most useful paleohydraulic calculation techniques were found to be the dimensionless shear approach applied to stream competence and bedload function theory applied to stream capacity. © 1974.
- Baker, V. R., & Milton, D. J. (1974). Erosion by catastrophic floods on Mars and Earth. Icarus, 23(1), 27-41.More infoAbstract: The large Martian channels, especially Kasei, Ares, Tiu, Simud, and Mangala Valles, show morphologic features strikingly similar to those of the Channeled Scabland of eastern Washington, produced by the catastrophic breakout floods of Pleistocene Lake Missoula. Features in the overall pattern include the great size, regional anastomosis, and low sinuosity of the channels. Erosional features are streamlined hills, longitudinal grooves, inner channel cataracts, scour upstream of flow obstacles, and perhaps marginal cataracts and butte and basin topography. Depositional features are bar complexes in expanding reaches and perhaps pendant bars and alcove bars. Scabland erosion takes place in exceedingly deep, swift floodwater acting on closely jointed bedrock as a hydrodynamic consequence of secondary flow phenomena, including various forms of macroturbulent votices and flow separations. If the analogy to the Channeled Scabland is correct, floods involving water discharges of millions of cubic meters per second and peak flow velocities of tens of meters per second, but perhaps lasting no more than a few days, have occurred on Mars. © 1974.
- Baker, V. R., Holz, R. K., & Hulke, S. D. (1974). HYDROGEOMORPHIC APPROACH TO EVALUATING FLOOD POTENTIAL IN CENTRAL TEXAS FROM ORBITAL AND SUBORBITAL REMOTE SENSING IMAGERY.. Array, 1, 629-645.More infoAbstract: Central Texas is subject to flooding of extraordinary magnitude, particularly in the frequency range of 10-50 years. Assuming that stream network geometry has been adjusted to these floods, quantitative drainage network analysis can be used to relate stream morphology to potential flood discharge. Stream network geometries were digitized from Skylab S-190B imagery, high-altitude and low-altitude aerial photographs, and large scale topographic maps. The digitzed data were then used to generate significant hydrogeomorphic parameters with the W. A. T. E. R. System, a computer program for watershed analysis. Refs.
- Baker, V. R. (2019, Fall). The abductive approach to synthetic autonomous reasoning. In Proc. SPIE 10982, Micro- and Nanotechnology Sensors, Systems, and Applications XI.
- Fink, W., Baker, V. R., & Others, . (2018, May/Spring). Tip- or Rollover protection mechanisms for planetary rovers enabling exploration of high-risk sites. In IEEE Aerospace Conference 2018 Proceedings, DOI: 10.1109/AERO.2018.8396821, 1-11.
- Liu, T., & Baker, V. R. (2018, August/Summer). Hydraulic modeling of megaflooding using terrestrial and Martian DEMs. In Geomorphometry Conference.
- Fink, W., Baker, V. R., Flammia, M., & Tarbell, M. A. (2015, March). Rover Traverse-‐Optimizing Planner For Multi-‐Objective Deployment Scenarios. In 2015 IEEE Aerospace Conference, 1-9.More infoInvited Speaker
- Fink, W., Fink, W., Baker, V. R., Baker, V. R., Hamilton, C. W., Hamilton, C. W., Schulze-Makuch, D., Schulze-Makuch, D., Tarbell, M. A., & Tarbell, M. A. (2015, March). Autonomous Exploration of Planetary Lava Tubes Using a Multi-Rover Framework. In IEEE Aerospace 2015.More infoFink, W., Baker, V.R., Schulze-Maduch, D., Hamiliton, C. W., and Tarbell, M.A., 2015, Autonomous exploration of planetary lava tubes using a multi-rover framework, in IEEE Aerospace Conference Proceedings, Big Sky, Montana. Paper number 2723, 9 p. doi: 10.1109/AERO.2015.7119315
- Baker, V. R. (2020, April). A machine learning approach to geomorphometry-extreme flooding links in the Lower Colorado River Basin. El Dia del Agua Conference. Tucson, Arizona: University of Arizona Department of Hydrology and Atmospheric Sciences.More infoAbstract for poster presentation by Lin Ji, V.R. Baker, V. Gupta, T.P.A. Ferre, T.P.A., and T. Liu
- Baker, V. R. (2020, June). Interpreting historical, botanical, and geological evidence to aid preparations for future floods. Sustainability Research and Innovation. Brisbane, Australia.More infoWilhelm, B., Ballesteros Canovas, J.A., Macdonald, N., Toonen, W.H.J., Baker, V., and 17 others, 2020, Interpreting historical, botanical, and geological evidence to aid preparations for future floods, in Abstract for the conference Sustainability Research and Innovation, Brisbane, Australia, June 14-17, 2020
- Ji, L., Baker, V. R., Gupta, H. V., Ferre, P. A., & Liu, T. (2020, Fall). Machine learning analysis of morphometry-extreme flood links in the Lower Colorado River Basin. 2020 Fall Meeting of the American Geophysical Union, Online, Dec 7-11. Online: American Geophysical Union.More infoL Ji, VR Baker, HV Gupta, PA Ferre, T Liu (2020), Machine learning analysis of morphometry-extreme flood links in the Lower Colorado River Basin, Session NH004 - Data Science and Machine Learning for Natural Hazard Sciences, presented at 2020 Fall Meeting of the American Geophysical Union, Online, Dec 1-17.
- Baker, V. R. (2019, April/Spring). An abductive approach to synthetic autonomous reasoning. SPIE DCS19 Micro-Nanotechnology Sensors, Systems and Applications Conference. Baltimore, Maryland: SPIE.
- Baker, V. R. (2019, September/Spring). 50 Years of Imaging Fluvial Features on Mars: A Continuing History of Thrilling Discovery. Geological Society of America Annual Meeting. Phoenix, Arizona: The Geological Society of America.
- Baker, V. R. (2019, September/Spring). Cataclysmic Flooding and Catastrophism: 350 Years of Geological Controversy. Geological Society of America Annual Meeting. Phoenix, Arizona: The Geological Society of America.
- Baker, V. R. (2019, September/Spring). The Sciences of Global Megaflooding, Paleoflood Hydrology, and Modern Flood Risks. Prognostics and Health Management Conference. Scottsdale, Arizona: Prognostics and Health Management Society.
- Baker, V. R. (2019, September/Spring). The modern evolution of geomorphology – Binghamton and personal perspectives, 1970-2019 and beyond. Binghamton Geomorphology Symposium, 50th Anniversary Meeting. Metropolitan State University of Denver, Denver, Colorado,.
- Liu, T., Baker, V. R., Harden, T., & Cline, M. (2019, November/Winter). Holocene floods and their climatological context, upper Colorado River Basin, U.S.A.. Floods in a Warmer World: Insights from Paleohydrology, Workshop of the PAGES Flood Working Group. Geneva, Switzerland: PAGES Flood Working Group.
- Liu, T., Greenbaum, N., Baker, V. R., Onken, J., Weisheit, J., Porat, N., & Rittenauer, T. (2019, December/Winter). Paleoflood Hydrology on the lower Green River, upper Colorado River Basin, USA. American Geophysical Union Annual Meeting. San Francisco, California: American Geophysical Union.
- Riedesel, S., Pearce, N. J., Roberts, H. M., Duller, G. A., Jenson, B., O'Connor, J. E., & Baker, V. R. (2019, July/Summer). Establishing a tephra- and luminescence-based chronology for glacial lake outburst flood deposits in the Channeled Scabland of North America. International Quaternary Association (INQUA) Congress. Dublin, Ireland: INQUA.
- Rodriguez, A., Kargel, J. S., Baker, V. R., Robertson, D. K., Komatsu, G., Berman, D. C., & Leonard, G. J. (2019, March/Spring). A NASA spacecraft may have landed on an early Mars mega-tsunami deposit in 1976. 50th Lunar and Planetary Science Conference. Houston, Texas: Lunar and Planetary Institute.
- Rodriguez, A., Kargel, J. S., Oehler, D. Z., Crown, D. A., Baker, V. R., & Komatsu, G. (2019, March/Spring). Potential cryospheric mud volcanism in he northern plain of mars: Geologic and astrobiological implications. 50th Lunar and Planetary Science Conference. Houston, Texas: Lunar and Planetary Institute.
- Baker, V. R. (2017, September). Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coast of Early Mars. Fourth International Conference on Early Mars. Flagstaff, Arizona: Lunar and Planetary Institute.More infoRodriguez, J.A.P., Linares, R., Zarroca, M., Komatsu, G., Oehler, D., Davila, A., Berman, D., and Baker, V., 2017, Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coast of Early Mars, in Fourth International Conference on Early Mars, Lunar and Planetary Institute, Houston, Texas, Abstract Number 3032.
- Baker, V. R. (2018, April/Spring). Models and Morphology: Achieving Planetary Geomorphological Uberty (Abstract Number 8376). European Geosciences Union, Annual Conference. Vienna, Austria: European Geosciences Union.
- Baker, V. R. (2018, August/Summer). Philosophy of science and John Shaw’s subglacial megaflooding hypothesis. CANQUA/AMQUA Biennial Conference. Ottawa, Canada: Canadian Quaternary Association (CANQUA).
- Baker, V. R. (2018, December/Winter). Failing to communicate: The “hundred-year” flood concept (Abstract PA51A-03). American Geophysical Union Annual Meeting. Washington, D.C.: American Geophysical Union.
- Baker, V. R. (2018, December/Winter). G.K. Gilbert’s investigative scientific methodology: Philosophical foundations and continuing relevance (abstract U32A-03).. American Geophysical Union Annual Meeting. Washington, D.C.: American Geophysical Union.
- Baker, V. R. (2018, March/Spring). Long-term hydrological cycling on early Mars (Abstract Number 1831). 49th Lunar and Planetary Science Conference. Houston, Texas: Lunar and Planetary Institute.
- Baker, V. R. (2018, November/Fall). What has happened can happen: Commonsense warnings about the future. Geological Society of America Annual Meeting. Indianapolis, Indiana: The Geological Society of America.
- Liu, T., & Baker, V. R. (2018, April 2018). Paleoflood hydrology of the lower Green River, upper Colorado River Basin, Utah. El Dia del Agua e la Atmosfera, School of Earth and Atmospheric Sciences. University of Arizona: Department of Hydrology and Atmospheric Sciences.
- Liu, T., & Baker, V. R. (2018, April/Spring). Epistemic Uncertainty, Extreme Flood Risk, and Paleoflood Hydrology (Abstract Number 9435). European Geosciences Union Annual Meeting. Vienna, Austria: European Geoscieces Union.
- Liu, T., & Baker, V. R. (2018, December/Fall). Modeling Megafloods: Using 2D Hydraulic Simulation to Understand the Megaflood Landscapes of the Northwestern U.S.. American Geophysical Union Annual Meeing. Washington, D.C.: American Geophysical Union.
- Lotsari, E., House, K., Alho, P., & Baker, V. R. (2017, April). Comparison of long-term evolutionary trajectories of two ephemeral channels after channel-forming extraordinary floods. European Geosciences Union Annual Conference. Vienna, Austria: European Geosciences Union.More infoLotsari, E., House, K., Alho, P., and Baker, V.R., 2017, Comparison of long-term evolutionary trajectories of two ephemeral channels after channel-forming extraordinary floods, in European Geosciences Union, Geophysical Research Abstracts, v. 19, number 8952.
- Rodriguez, A., Domingue, D. L., Kargel, J. S., & Baker, V. R. (2018, March/Spring). Evidence Of Pervasive Collapse Over A Buried Volatile-Rich Crust On Mercury. 49th Lunar and Planetary Science Conference. Houston, Texas: Lunar and Planetary Institute.
- Rodriguez, A., Domingue, D. L., Kargel, J. S., & Baker, V. R. (2018, May/2018). The Chaotic Terrains of Mercury: A History of Large-Scale Crustal Devolatilization. Mercury: Current and Future Science of the Innermost Planet. Columbia, Maryland: Lunar and Planetary Institute.
- Baker, V. R. (2017, June). High-Energy Megafloods and Ice Sheets. Geological Society of America, Rocky Mountain Section Meeting. Calgary, Alberta, Canada: The Geological Society of America.More infoBaker, V.R., 2017, High-Energy Megafloods and Ice Sheets, in Geogical Society of America Abstracts with Programs. Vol. 49, No. 5, doi: 10.1130/abs/2017RM-293123
- Baker, V. R. (2017, May). Paleoflood Data and Increasing Flood Extremes. PAGES Zaragoza Open Science Meeting: Global Challenges for Our Common Future: A Paleoscience Perspective. Zaragoza, Spain: PAGES - Past Global Changes.More infoBaker, V.R., 2017, Paleoflood Data and Increasing Flood Extremes: Abstract Book for PAGES Zaragoza Open Science Meeting: Global Challenges for Our Common Future: A Paleoscience Perspective, Zaragoza, Spain, p. 15.
- Baker, V. R. (2017, October). The Supreme Importance of Geological Thinking for Coping with Natural Hazard Events. Geological Society of America Annual Meeting. Seattle, Washington: The Geological Society of America.More infoBaker, V.R., 2017, The Supreme Importance of Geological Thinking for Coping with Natural Hazard Events, in Geological Society of America Abstracts with Programs, Vol. 49, No. 6doi: 10.1130/abs/2017AM-297273
- Baker, V. R. (2017, September). Early Mars as an Evolving “Ocean World”. Fourth International Conference on Early Mars. Flagstaff, Arizona: Lunar and Planetary Institute.More infoBaker, V.R., 2017, Early Mars as an Evolving “Ocean World,” in Fourth International Conference on Early Mars, Lunar and Planetary Institute, Houston, Texas, Abstract Number 3067.
- Baker, V. R., Maruyama, S., & Dohm, J. M. (2017, March). The Watery Origin and Evolution of Mars: A Geological Perspective. Lunar and Planetary Science Conference XLVIII. Houston, Texas: Lunar and Planetary Institute.More infoBaker, V.R., Maruyama, S., and Dohm, J.M., 2017, The Watery Origin and Evolution of Mars: A Geological Perspective, in Lunar and Planetary Science Conference XLVIII, Lunar and Planetary Institute, Houston, Texas, Abstract No. 3015.
- Lotsari, E., Hous, K., Alho, P., & Baker, V. R. (2017, April). Comparison of long-term evolutionary trajectories of two ephemeral channels after channel-forming extraordinary floods. European Geosciences Union Annual Conference. Vienna, Austria: European Geosciences Union.More infoLotsari, E., House, K., Alho, P., and Baker, V.R., 2017, Comparison of long-term evolutionary trajectories of two ephemeral channels after channel-forming extraordinary floods, in European Geosciences Union, Geophysical Research Abstracts, v. 19, number 8952.
- Lotsari, E., Lotsari, E., Hous, K., House, K., Alho, P., Alho, P., Baker, V. R., & Baker, V. R. (2017, April). Comparison of long-term evolutionary trajectories of two ephemeral channels after channel-forming extraordinary floods. European Geosciences Union Annual Conference. Vienna, Austria: European Geosciences Union.More infoLotsari, E., House, K., Alho, P., and Baker, V.R., 2017, Comparison of long-term evolutionary trajectories of two ephemeral channels after channel-forming extraordinary floods, in European Geosciences Union, Geophysical Research Abstracts, v. 19, number 8952.
- Rodriguez, A., Baker, V. R., Many Others, ., & Baker, V. R. (2017, September). Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coast of Early Mars. Fourth International Conference on Early Mars. Flagstaff, Arizona: Lunar and Planetary Institute.More infoRodriguez, J.A.P., Linares, R., Zarroca, M., Komatsu, G., Oehler, D., Davila, A., Berman, D., and Baker, V., 2017, Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coast of Early Mars, in Fourth International Conference on Early Mars, Lunar and Planetary Institute, Houston, Texas, Abstract Number 3032.
- Rodriguez, A., Many Others, ., & Baker, V. R. (2017, September). Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coast of Early Mars. Fourth International Conference on Early Mars. Flagstaff, Arizona: Lunar and Planetary Institute.More infoRodriguez, J.A.P., Linares, R., Zarroca, M., Komatsu, G., Oehler, D., Davila, A., Berman, D., and Baker, V., 2017, Detecting Astrobiologically Significant Ocean Floor Sediments in the Tsunami-Battered Coast of Early Mars, in Fourth International Conference on Early Mars, Lunar and Planetary Institute, Houston, Texas, Abstract Number 3032.
- Baker, V. R. (2016, December). An Outrageous Geological Hypothesis for the Early Mars Hydroclimatic Conundrum. American Geophysical Union Annual Meeting. San Francisco, CA: American Geophysical Union.
- Baker, V. R. (2016, December). Paleoetiological Extreme Flood Hydrology: Letting Nature’s Realities Inform Risk, Resilience, and Reduction of Vulnerabilities to Extreme Flooding During an Uncertain Future of Climate Change. American Geophysical Union Annual Meeting. San Francisco, CA: American Geophysical Union.
- Baker, V. R. (2016, December). Scientific Thinking to Remedy “Black Swans,” Wicked Problems,” and Assorted Science/Policy Failures. Water Resources Researches Institute Seminar Series. Tucson, Arizona: University of Arizona Water Resources Research Instiute.
- Baker, V. R. (2016, June). Global Extreme Flood Archive for Advancing Science and Hazard Mitigation. Cross Community Workshop on Past Flood Variability. Grenoble, France: PAGES (Past Global Changes).
- Baker, V. R. (2016, May). Channeled Scabland Megaflooding: Past, Present, and Future. Rocky Mountain Section Meeting, Geological Society of America. Pullman, Washington: Geological Society of America.
- Baker, V. R. (2016, September). A Half-Century of Paleoflood Hydrology: What Next?. 5th International Paleoflood Conference. Rapid City, South Dakota: International Paleoflood Conference.
- Baker, V. R. (2016, September). History and development of paleoflood hydrology in China. 5th International Paleoflood Conference. Rapid City, South Dakota: International Paleoflood Conference.
- Baker, V. R., & Baker, V. R. (2016, October). The Supreme Scientific Importance of Geological Thinking. University of Arizona Geosciences Department Colloquium Series. Tucson, AZ: Geosciences Department, University of Arizona.
- Baker, V. R. (2015, July). Extreme Events and Catastrophism in Geomorphology: Some Historical and Philosophical Perspectives. International Conference on Gradualism and Catastrophism in Landscape Evolution. Altai State University, Barnaul, Russia: International Association of Geomorphologists.
- Baker, V. R. (2015, July). The Role of Cataclysmic Flooding in Landscape Evolution. International Conference on Gradualism and Catastrophism in Landscape Evolution. Altai State University, Barnaul, Russia: International Association of Geomorphologists.
- Baker, V. R. (2014, October). Geological Hypotheses: Multiple, Working and Outrageous. “Great Ideas in Geology” session at Geological Society of America Annual Meeting. Vancouver, Canada: The Geological Society of America.
- Baker, V. R. (2014, October). Late Pleistocene Megaflooding from the Cordilleran Ice Sheet: New Data and New Questions. Geological Society of America Annual Meeting. Vancouver, Canada: The Geological Society of America.
- Baker, V. R. (2017, March). Tsunami Waves Extensively Resurfaced Shorelines of an Early martian Ocean. Lunar Lunar and Planetary Science Conference XLVII. Houston, Texas: Lunar and Planetary Institute.More infoRodriguez, J.A.P. , Fairén, A.G., Linares, R., Zarroca, M., Platz, T., Komatsu, G., Kargel, J.S., Gulick, V., Jianguo, Y., Higuchi, K., Miyamoto, H., Baker, V.R., and Glines, N., 2017, Tsunami Waves Extensively Resurfaced Shorelines of an Early martian Ocean, in Lunar Lunar and Planetary Science Conference XLVII, Lunar and Planetary Institute, Houston, Texas, Abstract Number 1680.
- Baker, V. R. (2016, March). Non-unique systems of features on Mars and Earth: Possible telltale signatures of ancient dynamic lithospheric mobility including plate tectonism. Lunar Lunar and Planetary Science Conference XLVII. Houston, TX: Lunar and Planetary Institute, Houston, Texas.
- Baker, V. R. (2016, March). Tsunami Waves Extensively Resurfaced Shorelines of an Early martina Ocean. Lunar and Planetary Science Conference XLVII. Houston, TX: Lunar and Planetary Institute, Houston, Texas.
- Baker, V. R., Hirschboeck, K. K., & Roy, T. (2016, September). Changes in channel geomorphology and their potential impacts on flood behavior: A case study for the Rillito Creek in Tucson, Arizona. 2016 Annual Symposium Arizona Hydrological Society. Tucson, Arizona: Arizona Hydrological Society.
- Baker, V. R. (2016. Co-Leader: Field trip for 5th International Paleoflood Conference. Rapid City, South Dakota. From Portland, Oregon, to Rapid City, South Dakota: International Paleoflood Conference.More infoI was a co-leader for the pre-meeting field trip, September 6-10, 2016, from Portland, OR, to Rapid City, SD, covering the Pleistocene megaflooding landscapes of the northwestern U.S. The impoverished limitations of the on-line format for this performance report does not allow for proper reporting of the diverse creative acts of scholarship that make for the most productive contribution to the intellectual health of the university environment. I suggest that those in power re-think the means of reporting on things are most creative for a fruitful university experience.
- Baker, V. R. (2016. Field Trip Leader: “Pleistocene Megaflood Landscapes of the Channeled Scabland". Rocky Mountain Section Meeting, Geological Society of America, Pullman, Washington. East-Central Washington State: Geological Society of America.More infoI led a 3-day geological field trip through the Pleistocene megaflooding landscapes of the Channeled Scabland region of eastern Washington state. The on-line system has not appropriate category for this activity.
- Baker, V. R. (2015. Co-Leader: Field trip for 5th International Paleoflood Conference. Rapid City, South Dakota. From Portland, Oregon, to Rapid City, South Dakota: International Paleoflood Conference.More infoI was a co-leader for the pre-meeting field trip, September 6-10, 2016, from Portland, OR, to Rapid City, SD, covering the Pleistocene megaflooding landscapes of the northwestern U.S. The impoverished limitations of the on-line format for this performance report does not allow for proper reporting of the diverse creative acts of scholarship that make for the most productive contribution to the intellectual health of the university environment. I suggest that those in power re-think the means of reporting on things are most creative for a fruitful university experience.
- Baker, V. R. (2015. Field Trip Leader: “Pleistocene Megaflood Landscapes of the Channeled Scabland". Rocky Mountain Section Meeting, Geological Society of America, Pullman, Washington. East-Central Washington State: Geological Society of America.More infoI led a 3-day geological field trip through the Pleistocene megaflooding landscapes of the Channeled Scabland region of eastern Washington state. The on-line system has not appropriate category for this activity.
- O'Connor, J. E., Baker, V. R., Waitt, R., & Balbas, A. (2017, October). Co-Leader Field Trip 402: "Late Pleistocene Glaciation and Megafloods: The Cordilleran Ice Sheet and Columbia River Valley, Drainage Diversions and Megafloods from Glacial Lake Missoula and Glacial Lake Columbia". The Geological Society of America.More infoOctober 18-21, I Co-led a Field Trip for the Geological Society of America Annual Meeting (Seattle, Washington)
- Baker, V. R. (2016, August). Foreword. BOOK: Lake Bonneville: A Scientific Update.