181 Quaternary Geology/Geomorphology IV

Thursday, 8 November 2001
1:30 PM - 5:30 PM

QUANTITATIVE ANALYSIS OF MICROSCOPIC CHARCOAL FROM SEDIMENTS OF A LATE PLEISTOCENE LAKE, DUTCHESS COUNTY, NY

Paper number: 181-15
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

The period following the retreat of the Laurentide Ice Sheet in the late Pleistocene is significant in the Lower Hudson Valley of New York State. This span of approximately 5,000 years between glacial retreat and the beginning of the Holocene saw the great megafaunal extinction, the introduction of human populations upon the landscape, and the well-documented cooler and drier Younger Dryas climatic event in the northeastern United States.

It has been shown that charcoal fragments contained in the sedimentological record of Quaternary lakes can be used as indicators of fire frequency, intensity and proximity. A 196 cm core collected from the Hyde Park Mastodon Site in Hyde Park, New York, reveals three distinct units: silty clay (100-196 cm), silty marl (40-100 cm) and organic peat (0-40 cm). Stratigraphic analysis and preliminary pollen counts have shown that this core record extends from about 15,000 to 10,000 years before present. Both macroscopic and microscopic charcoal fragments have been observed in all three units within the core, with the frequency increasing in the carbonate- and organic-rich sections. By quantifying the microscopic charcoal preserved in these lacustrine sediments, it is possible to provide evidence for changes in wildfire regimes within the rapidly shifting ecozones of the recently deglaciated and ameliorating climatic conditions of southeastern New York in the late Pleistocene. Forthcoming radiocarbon dates will allow for increased temporal control of this site, and ongoing research will continue to shed light on this evolving landscape.