TIMING OF PLEISTOCENE GLACIAL EVENTS IN NEW-YORK-STATE

This review of age data for the Pleistocene of New York identifies both strengths and weaknesses in the temporal framework relating the glacial chronology of the Great Lakes region to that of the middle Atlantic seaboard. The pre-Wisconsinan record involves saprolith and till in the Adirondack Mountains, marine clay on Long Island, multiple tills at Fernbank, Otto, and Gowanda, and major drainage derangement of the Allegheny River. Middle Wisconsinan ice spread into the Allegheny Plateau, damming high-level lakes in Cayuga Trough and southern Ontario. Long Island pollen data show late Middle Wisconsinan warming, the Plum Point Interstade. Glacially overridden organic matter at Rush Creek, Lord Hill, and St. Davids shows that this episode ended by 24 000 BP. Maximum Late Wisconsinan glaciation occurred during the Nissouri Stade, 21 750 - 18 570 BP. The concept of an Erie Interstade implies that ice recession, 15 000 - 16 000 BP, permitted lake drainage across New York. New York evidence allows this interpretation. but fails to establish the extent of ice withdrawal. Port Bruce drift incorporates Erie Interstade take sediments. Radiocarbon data at Nichols Brook suggest that Valley Heads recession began by 14 000 BP. About 13 000 BP, the Port Huron Advance to the Hamburg Moraine dammed Lake Whittlesey. Subsequent glacial recession opened eastward drainage before readvance restored Lake Warren. By 12 000 BP, Lake Iroquois occupied the Ontario plain. Pollen data indicate that marine incursion of the St. Lawrence Valley occurred 500 - 1000 years later than suggested by shell dates.