A GIS STUDY OF GLACIAL AND POST-GLACIAL GEOMORPHOLOGY IN WESTERN NEW YORK

In the early 20th century, Leroy Fairchild correlated beaches, terraces, etc., throughout New York state. He concluded that prior to Post Glacial Rebound (PGR) there had been a northeastward trending tilt of the surface by a foot or so per mile. Today a GIS can be used to manipulate DEMs and see to what extent they support his results. DEMs with a spatial resolution of 10 m (7.5 minute UTM quadrangles) and about 30 m (1 second of arc on a 1 degree geographic quadrangle) were used. Initially, work focused on western New York, particularly regions in the vicinity of glacial Lake Hornell. Fairchild's tilt was restored, and then the distribution of elevations was examined to identify those post glacial elevations most likely representing still stands of proglacial lakes. Because the scale of the features sought was similar to the resolution of the DEMs, spatial averaging to reduce interpolation artifacts was not desirable, and other approaches were used. Results were checked against the DEMs and topographic maps to identify anthropogenic effects (quarries, highways, real estate development, etc.). Field studies confirmed the presence of gently sloping nearly planar surfaces at some of the identified elevations. Projecting the results to the northern parts of the state resulted in maps which may be useful in providing targets for further study.