A LACUSTRINE RECORD OF LATE-QUATERNARY ENVIRONMENTAL CHANGE FROM HARDING LAKE, ALASKAN INTERIOR

Sediment cores recovered from Harding Lake (64.421° N, 146.854° W; 217 m ASL) in March 2010 are used to document late-Quaternary environmental change in the interior of Alaska. During the Last Glacial Maximum (LGM), the Alaskan Mountains were extensively glaciated leaving Beringia and the Alaskan interior largely ice-free. Regional proxy records from the Tanana Valley demonstrate the interior of Alaska was characterized by abrupt climatic transitions during the Holocene, based on pollen analysis and lacustrine sedimentology. The full glacial climate in interior Alaska was extremely arid and cold, producing lower lake-levels resulting in the desiccation of shallow lakes. With a maximum depth of 43 meters, Harding Lake likely persisted during the LGM potentially archiving a continuous record of environmental change from the glacial-interglacial transition. Lacustrine cores were analyzed for bulk density, organic matter, carbonate content, residual mineral matter, magnetic susceptibility, and are dated using Accelerator Mass Spectrometry (AMS) ¹⁴C on discrete terrestrial macrofossils. These results will provide a high-resolution, potentially longer duration record of lake-level change and water balance, elucidating the nature of environmental conditions in the interior of Alaska during the late Pleistocene and Holocene.