Late Pleistocene Chronology of Lake Terreton, Southeastern Idaho, Poster 22

A better understanding of Late Pleistocene climate change in the western US is important because it can help to calibrate climate models designed to predict future climate change. Shorelines of closed lake basins provide... [ view full abstract ]

A better understanding of Late Pleistocene climate change in the western US is important because it can help to calibrate climate models designed to predict future climate change. Shorelines of closed lake basins provide excellent climatic records, and are particularly valuable as records of high stands caused by wetter and/or cooler conditions. Lake Terreton was a large lake situated on the eastern Snake River Plain, an area with relatively few direct climate proxies. The lake occupied the Mud Lake and Big Lost Trough sub-basins around the time of the last glacial maximum. 35 samples of shoreline-proximal sands were collected from outcrops and hand-dug soil pits. OSL ages for 19 of the samples indicate that the lake reached its highest level three times during the Late Pleistocene; first at ~8.0 ka, second at ~11,000 ka, and third at ~34.5 ka. The mechanisms responsible for the high stands may vary. One sample indicates a lower high stand at ~23 ka, which matches the timing of the Big Lost River Flood which flowed into the Terreton Basin. The younger high stands tentatively correlate with known climatic anomalies in the North Atlantic although additional work is required to place them in a regional context.