CONTEMPORARY AND PRIOR ENVIRONMENTS OF THE HYDE PARK, NEW YORK, MASTODON ON THE BASIS OF ASSOCIATED PLANT MACROFOSSILS

Excavations in 1999 and 2000 for a pond (40°46’45”N, 73°53’40”W; 68 m asl), 3 km east of Hyde Park, Dutchess County, New York, uncovered a nearly complete mastodon skeleton in sediments of a small shallow basin associated with the Hyde Park moraine. Large-volume sediment samples were taken from 10-cm intervals from the wall of an open trench (HPM-2) dug near the mastodon remains (0-100 cm) and by bucket auger and post-hole digger (100-190 cm). Gravel and cobbles prohibited further sampling below 190 cm, and the uppermost peat (above 0 cm) was discarded because of disturbance. Plant macrofossils were present in 250-ìm-mesh sieve residues in all samples. Above 65 cm spruce (Picea sp.) needles occurred in abundance. Below that depth spruce was poorly represented, and the macrofossil record was dominated by indicators of open-ground (tundra) vegetation (Dryas integrifolia, Salix herbacea, Saxifraga spp., Armeria sp., Potentilla sp., Caryophyllaceae). Seeds and fruits of aquatic plants (Myriophyllum sibiricum, Najas flexilis, Potamogeton spp., Callitriche sp., Sagittaria sp., Sparganium sp., Cyperaceae) were present at all depths. Pond water was circumneutral to calcareous (pH range 6.8–9.8), with alkalinity between 13.5 and 123.5 mg/l, on the basis of measurements of water in which M. sibiricum grows at present. The interval 85–55 cm is marked by an increase in marl and a decrease in silt and clay and has been dated elsewhere in the basin at 12,970 ± 40 to 12,410 ± 50 yr B.P. The sediments document a change from an open nearly treeless landscape to spruce-rich forest and conditions that permitted a major increase in spruce abundance. The mastodon skeleton occurred in sediments containing spruce needles.