TIMING OF PLEISTOCENE GLACIAL EVENTS IN NEW-YORK-STATE

This review of age data for the Pleistocene of New York identifies bot h strengths and weaknesses in the temporal framework relating the glac ial chronology of the Great Lakes region to that of the middle Atlanti c seaboard. The pre-Wisconsinan record involves saprolith and till in the Adirondack Mountains, marine clay on Long Island, multiple tills a t Fernbank, Otto, and Gowanda, and major drainage derangement of the A llegheny River. Middle Wisconsinan ice spread into the Allegheny Plate au, damming high-level lakes in Cayuga Trough and southern Ontario. Lo ng Island pollen data show late Middle Wisconsinan warming, the Plum P oint Interstade. Glacially overridden organic matter at Rush Creek, Lo rd Hill, and St. Davids shows that this episode ended by 24 000 BP. Ma ximum 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 Yor k. New York evidence allows this interpretation. but fails to establis h the extent of ice withdrawal. Port Bruce drift incorporates Erie Int erstade 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. Subsequen t 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.