CHANGES IN ATTITUDES #1 THE SLOPE OF THE WATER PLANES OF GLACIAL LAKE ALBANY, HUDSON LOWLANDS, NY

The early studies of the glacial features in the Hudson Lowlands have focused primarily on ice margins and lake deposits. Maps of ice margins were published by J.B. Woodworth in 1905. He also noted various lake features and postulated an isostatic tilt of 2 ft/mile on lake planes that he assigned to “Lake Albany.” He wrote that the ice retreated from the uplands, leaving a relatively narrow, active glacial tongue in the Lowlands centered on the Hudson Gorge. In 1918, H. Fairchild postulated a narrow marine strait through the Hudson and Champlain Lowlands to the Champlain Sea. He charted a 2.2 to 2.5 ft/mile isostatic tilt caused by delayed uplift. Later workers determined that the water planes recorded several lake stages and had gradients of 2.7 to 2.1 ft/mi. They also noted landforms that documented both stagnant and active ice retreat. Mapping for the Surficial Geologic Map of New York generated a flood of reconnaissance surficial maps. The maps confirmed or identified deltas, subaqueous fans, beaches, and lake plains that provided an expanded data base for additional studies. A challenge to the isostatic tilt interpretation and lake stages emerged as workers in the Ontario Basin (D. Pair and others) and the Connecticut Lowlands (Kotef, the Stones, and others) proposed isostatic tilts of 4 to 5 ft/mi. In 2009, S. Stanford suggested a tilt of 4 ft/mi with rising sea level being the control on the lake outlet. The ice-contact deltas on his rebound chart mark a slope of approximately 2 ft/mile.