Holocene Paleoclimatic History of the Rainfall Gradient in the Southern Great Plains: Evidence from Stable Isotopes in Land Snail Shells

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SBR-9510869 Glenn A. Goodfriend, Principal Investigator (PI) G.L. Ellis, Co-PI Texas Historical Commission Holocene Paleoclimatic History of the Rainfall Gradient in the Southern Great Plains The Great Plains represent the climatic transition between moist eastern and semiarid western North America. This project investigates the climate history of this rainfall gradient in the southern Great Plains over the course of the Holocene (the period following the end of the last ice age or the last 10,000 years). The paleoclimate reconstruction is based on the stable isotope composition of the carbonate fraction of shells of the land snail, Rabdotus, which is abundant in the late Quaternary record of the region. Samples from four Texas sites spanning the modern rainfall gradient in the region are analyzed for stable carbon and oxygen isotope ratios. These ratios serve as proxies for determining plant types and seasonal variations in temperature. Documenting the recent history (last 10,000 years) of this rainfall gradient is of critical importance in evaluating paleoclimatic models of the Holocene and understanding how the gradient could change in the future in response to human-induced modifications. The data also provides a basis for reinterpreting and refining current understanding of the patterns of cultural adaptation in the region.