TESTING THE EFFECTIVNESS OF GLACIER EROSION BY CHANNEL ANALYSES: NORTHEASTERN OHIO, USA

A mosaic of multiple-aged channels is incised into a bedrock cuesta in northeastern Ohio and is preserved beneath a veneer of glacial drift. This channelized area is bounded to the north by the cuesta escarpment, the east and west by glaciated lowlands and to the south by the glacial limit. Because of the cuesta's unique position, the relative significance of fluvial and glacial influences on this landscape can be evaluated by channel analyses.

Through GIS analysis of borehole, surficial Digital Elevation Models (DEMs), structure and stratigraphy data from the area, >30 channels composing three independent morphologies have been identified: Type A) Two large >50 kilometers long by >1 kilometer wide by >100 meters deep (>50 km x >1 km x >100 m), linear channels with flat long profiles and steep sides that flank the cuesta; Type B) Four medium (<50 km x ~0.5 km x <100 m) concave-north, curvilinear channels that cross the cuesta and modern drainage divides; and Type C) >25 smaller (~5 km x 0.3 km x 30 m) complex and orthogonally cross-cutting channels incised atop the cuesta. After evaluating each morphology type against established channel origins, it is suggested that Type A and B channels are glacially modified fluvial channels and Type C channels are predominately glacier derived. An analysis of channel thalweg elevations is interpreted as a result of multiple stages and/or intensities of glacial modification. These disparities also suggest that a glacier's ability to efface the landscape is limited on a cuesta; conversely, the adjacent lowlands (e.g., Grand River Low Plateau) suggest spatial differences in a glacier's erosive ability.