THE POST-LAST GLACIAL MAXIMUM GLACIER RECORD OF THE TAMARACK BENCH OF THE EASTERN ROCK CREEK DRAINAGE, EASTERN SIERRA NEVADA MOUNTAINS, CALIFORNIA

The eastern Sierra Nevada Mountains present one of the longest and best preserved paleoglacial records available; however due to the discontinuity of the moraine record and the shortage of reliable absolute dating techniques for paleoglacial research, the late-Pleistocene and Holocene glacial history remains poorly constrained. The Tamarack Bench of the eastern Rock Creek drainage is characterized by a series of moraines and post-glacial lakes that lie between the well developed Tioga (14-32ka) and Matthes (600-100ya) moraines. Four separate Tamarack Bench advances were mapped. Based on stratigraphic and cross-cutting relationships combined with relative dating criteria, the three older moraines are determined to correlate with deposits in the main Rock Creek canyon. The fourth and youngest moraine postdates the series preserved in Rock Creek. Lake sediment cores were extracted from four moraine dammed, post-glacial lakes to obtain radiometric carbon age dates. Well the cores were primarily organic rich mud, three isolated white sandy layers are interpreted to represent glacial advances in the upper water shed, postdating the lake forming moraine. Bounding radiocarbon ages on discrete organic detritus were obtained for the sand layers suggesting neoglacial advances occurred between 1750-1510 cal yr BP, 960-840 cal yr BP, and 770-580 cal yr BP. This evidence provides further insight into the relationship between the regional Sierra Nevada climate record and global climate trends.