A series of large, Late Wisconsinan meltwater floods through the Champlain and Hudson Valleys, New York State, USA

The Champlain Valley in northeastern New York lies at the junction of two important Late Wisconsinan proglacial outflow routes, the Hudson Valley to the south and the St. Lawrence Valley to the northeast. Freshwater outflow from proglacial lakes in the Hudson/Champlain valleys (glacial lake Albany/Vermont) and the combined Ontario and St. Lawrence valleys (glacial Lake Iroquois) may have affected ocean circulation and thereby altered climate during the last deglaciation. We have estimated steady-state and three flood pulse discharges from these large meltwater reservoirs into the North Atlantic using channel geometry and a high resolution digital elevation model of the Late Wisconsinan paleogeography of the region. We estimate the steady-state meltwater discharge into the North Atlantic to be 0.3–0.6 Sv. The first flood event was a combined Iroquois/Vermont outflow at around 10,900 14C yr BP that released 700 km3 of meltwater into the North Atlantic through the Hudson Valley with an estimated discharge of 1.1 Sv. A second outflow event released 2500 km3 through the Hudson Valley shortly after the first event. Finally, approximately 1500 km3 was released to the North Atlantic through the Gulf of St. Lawrence at the incursion of the Champlain Sea about 150–300 years later.