A REEXAMINATION OF MELTWATER ROUTING IN CENTRAL NEW YORK

Ongoing geologic mapping investigation of the Montezuma Wetlands Complex by the New York Geologic Survey has led to the reexamination of the intricate morphology of large glacial meltwater channels and also past glacial lake shore lines. The area under study is in the central portion of New York State and is characterized by the Lake Ontario Lowlands rising in elevation to the south to the Alleghany Plateau. The steep uplands are dissected by the deeply incised Finger Lakes and have most recently been influenced by the Laurentide Ice Sheet. Situated between the northern edge of the Finger Lakes and Lake Ontario, channels on the order of several hundred meters wide and 50 meters deep can be found. These channels that today contain at most underfit streams, probably drained meltwater from the retreating ice sheet. In this same area glacial lake shoreline features such as truncated drumlins, spits and bars can also be observed.

Geographic information system was used to ascertain the discharge pattern and direction of glacial meltwater as well as former glacial lake shorelines across the state. Topography from 10 meter digital elevations models as well as LiDAR, where available, was used to establish drainage routes through these channels as well as a reconstruction of the shoreline of glacial Lake Iroquois in central New York. Stream profiles of the channels provide insight to the relative timing of the drainage as well as the drainage direction. The shoreline of glacial Lake Iroquois was recreated by using tilted water planes at various slopes to match observed shoreline features and field observations with previous thresholds and drainages.

The profiling of the large channels has proved problematic on a regional scale as not only does the morphology of the channels change across central New York but the downward slope of the channel is not consistent with the eastern outlets proposed. Compounding this issue is the fact that there is an inability to match water planes and shoreline features of glacial Lake Iroquois in central New York such that the lake drains to the east.