NEW STRATIGRAPHIC SECTIONS AND CORES OF LATE QUATERNARY AGE FROM THE ONEIDA BASIN, NEW YORK

Three Quaternary sections were discovered along a remote section of the upper reach of Fish Creek between Blossvale and Becks Grove, New York. Here, Fish Creek has deeply incised some 100 m into an extensive terrace found along the southern boundary of the Tug Hill Plateau with the “Oneida” lowland. These exposures reveal the basal stratigraphy of an important Late Quaternary landform upon which smaller scale features of an eolian dune field reside. Most of the “terrace” is actually cored with ice contact sediments mostly over compacted and highly deformed muddy diamictons. These gray, glacigenic deposits are abruptly overlain by rhythmically laminated sands, silts, and clays with distinctive varved character. The laminated facies are then in turn succeeded by cross bedded and climbing ripple cross-laminated fine-grained sands. These are disconformably cut by coarse, gravelly sands with trough cross beds and overlying soil profiles, thus capping the terrace feature. The three stratigraphic exposures demonstrate that the terrace is a composite feature composed of a combination of several depositional and erosional episodes.

Upon Oneida Lake we utilized a new percussion core system to recover undisturbed cores of up to 2 m in length from seismic sequences first identified from earlier Chirp Surveys of the lake. We recovered for the first time within modern Oneida Lake a relict varved sequence, which we believe represent deposits from Glacial Lake Iroquois. Varves are some 7- 8 cm in thickness in the two intervals which we recovered, promising a high resolution record of the evolution of the lake basin during the late Glacial time. In addition we collected a new suite of cores and excavations from several landform associations in and around the Oneida Basin. The first of these was from the muck land regions south of Oneida Lake where we recovered at least 2 + m of marl which now has radiocarbon ages (gastropods) in succession from 4.4 to 6.ka We have yet to recover the entire thickness of the marl section at this locality so the potential for a nearly complete Holocene record is promising. Taken together these new stratigraphic sections help fill in important knowledge gaps in our understanding of the nature of deglaciation and subsequent environmental changes in the Central Oneida Lowland of New York.