USING LIDAR TO RECONSTRUCT GLACIAL LAKES IN CAYUGA COUNTY, NEW YORK

Located in the Finger Lakes Region of Central New York State, Cayuga County has been the focus of investigation by the New York Museum/New York Geological Survey since 2009. Encompassing a portion of New York’s drumlin swarm in the north, the county becomes rolling to the south as elevation increases and is dissected by deep glacial troughs. As the Laurentide Ice Sheet retreated across this area it acted as a dam creating a series of proglacial lakes. Landforms such as deltas, fans, and strandlines delineate portions of these former lake levels.

Using light detecting and ranging (LiDAR) elevation data, deltas, fans, and strandlines were noted and analyzed in an attempt to reconstruct the former proglacial lake levels. Reconstruction had to take into account glacial rebound as features for the same lake did not align horizontally. Using Arcmap10.1, elevation points of the features were used to create a sloping, planar surface that would connect each point. This water plane represents the former lake level. Reconstruction of the lake involved flattening this sloping plane which lowers the modern elevation of the features closest to the former ice margin.

At least 10 lake levels were recognized across Cayuga County. At 336 m above mean sea level (modern elevation) the highest elevation lake was along the southern boundary of the county. Near the northern edge of the county the lowest lake was 145 m amsl corresponding to Glacial Lake Iroquois. Reconstructed water planes ranged from 0.6 m/km to 0.9 m/km.