ADVANCES AND READVANCES: A REVIEW OF RECENT QUATERNARY MAPPING AND RESEARCH IN NEW ENGLAND AND ADJACENT CANADA

The past decade of Quaternary studies in the Northeast has seen progress on many fronts. Geologic mapping by government agencies is clarifying the region's glacial and postglacial stratigraphy. Mapping capabilities are enhanced by imaging techniques such as ground-penetrating radar and DEM's. The new Quaternary geologic map of Connecticut provides a synthesis of a state where detailed quadrangle mapping is already complete. Academic research on Northeastern Pleistocene geology remains focused on the latest deglaciation. “Growth industries” include the increasingly precise dating of glacial and climate events, and establishing connections with global terrestrial, marine, and ice-core climate records. Radiocarbon dating is augmented by luminescence and cosmogenic isotope dating methods, enabling age determinations for inorganic materials and insights concerning erosion history. The glacial Lake Hitchcock varve sequence in the Connecticut River valley has been calibrated by radiocarbon dates and correlated with other Northeastern varve series and the paleomagnetic record. This varve chronology now anchors much of the regional deglaciation history, but correlation with the glaciomarine chronology in Maine remains problematic because of uncertainties in the reservoir correction for marine fossil ages. Recent work in Québec points to a larger correction than previously assumed, thus helping to reconcile the SE Québec deglaciation chronology with western New England. Other developments include refinements in relative sea-level curves and related crustal isostatic history. End moraines supporting oscillatory retreat of active ice are being found in the interior of New England, and some of these deposits probably were climatically induced. Workers have validated the Littleton-Bethlehem moraine system in the White Mountains and tied it to the Older Dryas cold interval through dating of nearby Lake Hitchcock varves, the correlative Middlesex Readvance in Vermont, and basal sediments from pond cores. Mapping in Canada's Maritime Provinces reveals a complex ice-flow history related to growth and decay of local ice masses. Dated sub-till organics and moraine belts in Nova Scotia and New Brunswick, and pond cores from New England, indicate glacial expansion during the Younger Dryas climate event.