7 Paleoclimatology/Paleoceanography (Posters)

SEDIMENTOLOGICAL AND POLLEN ANALYSIS OF THE HYDE PARK MASTODON SITE, DUTCHESS COUNTY, NY

Paper number: 7-16
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

During the summer and fall of 2000, the Paleontological Research Institution excavated a newly discovered mastodon skeleton (Mammut americanum) in Hyde Park, New York. Located in a kettle pond just south of the Hyde Park Moraine, it was radiocarbon dated at 11,480 years b.p. Three sediment cores were extracted at the site. Core LP2A was taken through the ribcage of the mastodon and was analyzed in this study. Visual inspection combined with measurements of organic carbon and carbonate content reveal three distinct units in the core. From bottom to top these are: silty clay (100-196 cm), silty marl (40-100 cm), and organic peat (0-40 cm). The ribcage of the mastodon was located within the marl unit between about 70 and 100 cm depth, and therefore provides a minimum age estimate for the marl; the pelvis was found within the overlying peat.

Pollen analysis reveals generally low flux values between 196 and approximately 60 cm, with fluxes increasing dramatically in the upper part of the silty marl and the peat. Percentage abundance data show that spruce and pine forests dominated the region at the time of the mastodon, and that hardwood forests were just beginning to emerge. Hemlock appears only near the top of the record, suggesting that much of the Holocene is missing from the site, perhaps because of human disturbance. We await radiocarbon dates to provide further age control for the site and to look for evidence of proboscidian bioturbation that may have occurred when the mastodon foundered in the pond. Grain size, clay mineralogical, and heavy mineral analyses are also ongoing to characterize the source of sediment to the pond as well as to look for zones of sediment mixing.