EXTRAPOLATION OF THE LITTLETON-BETHLEHEM (OLDER DRYAS) AND PINEO RIDGE MORAINE SYSTEMS ACROSS NEW HAMPSHIRE AND MAINE

The Pineo Ridge moraines in eastern Maine and the Littleton-Bethlehem moraines in northern New Hampshire are among the most prominent moraine systems in northern New England. However, their relations to deglaciation and climate events in other parts of the region are not well defined. Our reconnaissance work suggests mappable continuations of the ice-margins associated with both of these moraine systems. The Pineo Ridge ice margin previously was traced only as far west as the glaciomarine delta complex near Cherryfield, but is now reinterpreted as bending to the southwest and continuing across the state. Ice-marginal deposits vary in type and magnitude along this trend, but include the Waldoboro Moraine and other large moraines, as well as ice-contact glaciolacustrine deltas in western Maine. It may be possible to trace the Pineo Ridge ice margin across central New Hampshire, but ongoing work will need to produce more field evidence and match the radiocarbon and varve chronologies between New Hampshire and SW Maine.

Previous studies indicate an age of ~ 14 cal ka for the Littleton-Bethlehem (L-B) moraine system in the northern White Mountains of New Hampshire, and these moraines are inferred to have resulted from Older Dryas climatic cooling. Cosmogenic exposure ages are being obtained by one of us (B. Hall) from a moraine in Littleton to help test this model. Larsen (2001) equated the L-B Readvance with the Middlesex Reavance of the same age to the west in Vermont. Thompson et al. (1999) further correlated the L-B moraines with other moraine clusters extending east to Randolph, NH (just north of Mt. Washington). We are investigating several possible extensions of this Older Dryas ice margin into western Maine. Newly discovered morainic components include clusters of till ridges and hummocks west of the Androscoggin River in Berlin. These deposits are concentrated in valleys between York Pond and Head Pond. They suggest that the ice front wrapped around the north side of the Crescent Range. The Berlin moraines may be correlated with the Success Moraine and related ice margin positions identified by Gerath (1978) on the proximal flank of the Mahoosuc Range near the ME-NH border, and thus limit the options for extending the Older Dryas ice margin into western Maine.