DRAINAGE HISTORY OF GLACIAL LAKE HITCHCOCK AND PALEOCLIMATIC IMPLICATIONS OF LATE QUATERNARY SEDIMENTS AND TERRACES IN THE CENTRAL CONNECTICUT VALLEY, NEW ENGLAND

Study of a continuous sequence of 1,389 varves from the Hadley Basin and nearby terraces of the Connecticut River provide confirming evidence for the timing of glacial ice retreat and local drainage of Glacial Lake Hitchcock. Based upon extrapolation to the oldest local varve/till contact, the Laurentide ice sheet retreated from the Amherst/Hadley area by 12.8 ka 14C yrs (15.4 ka cal. yrs BP). An AMS 14C age of 12,370 +/-120 (14.3 +1.2/-0.4 cal kyr BP) between Antevs' varve year 5761-5768 and optical luminescence ages between 14.0 cal. ka and 14.4 cal. ka on fossil sand dunes superimposed on the lake floor indicate that Lake Hitchcock drained from this part of the valley by 12.0 ka 14C yrs (14.0 cal. yrs BP). The late Pleistocene New England (NE) varve chronology from Glacial Lake Hitchcock, spanning the 4000-year period from 17,500 – 13,500 cal. yr BP, has been analyzed for inferences into the nature of interannual and decadal climate variability in New England during early deglaciation. Spectral analysis of the glacial varve chronology indicates a distinct interannual (3-7 year) band of enhanced variability suggestive of El Nino/Southern Oscillation (ENSO) teleconnections into eastern North America during the late Pleistocene. These variations occurred with the Laurentide Ice Sheet near its maximum extent and when climatic boundary conditions were different from today. The signal of El Nino-like variability weakens in the youngest portion of the record consistent with climate modeling. A weak but coherent 22-year period signal suggests the possible influence of solar-magnetic forcing (Hale solar cycle) on climate throughout the late Pleistocene.