The Fluvial Response to Late Quaternary Climatic Change of Large Rivers in France

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The mechanisms that produced past climate changes may have been global in extent, but the manifestation of such changes in the climate system and on terrestrial environments varied regionally. The need for increased understanding of this spatial and temporal variability has become even more significant in light of the recent results from ice core and marine records, which provide exciting new glimpses of the complexity the transition from the last full-glacial to Holocene transition. Unraveling the spatial and temporal variability of terrestrial systems and their responses to climate changes requires clearly dated stratigraphic records from representative parts of Earth's surface. Toward that end, this research project involving geographers and Earth scientists from the U.S., France, and the United Kingdom will develop a region record of late Pleistocene and Holocene landscape evolution for the Loire, Rhone, and Garonne rivers of southern France. Long-term project goals are to develop and refine geomorphic, stratigraphic, sedimentologic, and paleohydrologic models for the three systems in order to analyze how they operated over the course of a complete glacial-interglacial cycle. More specifically, the project will develop a general stratigraphic, sedimentologic, and chronologic framework for these river systems during the "Wurm glacial cycle." It also will develop a detailed stratigraphic, sedimentologic, and chronologic framework at millennial-scale resolution for the three river systems during the very dynamic period of deglaciation and transition to the Holocene. The chronology of glacio-fluvial sediments will be developed through the use of optically stimulated luminescence (OSL) and accelerator mass spectrometry (AMS) 14C dating procedures,. These data will be used to evaluate the frequency, magnitude, differential sensitivities, and thresholds for change in these fluvial systems over that critical time period. This research project will generate a valuable new database and contribute new insights into a range of important issues, including (1) linkages between regional climate and hydrological systems and global atmosphere-cryosphere-ocean processes and (2) regional sensitivities to climate change. The database will complement information gathered from individual river systems elsewhere and from relatively small regions, and it will provide a reference standard for future studies conducted on a regional scale. The project is jointly supported by the Geography and Regional Science, Geology and Paleontology, and Western European programs at the National Science Foundation in collaboration with the French National Center for Scientific Research (CNRS).