ON THE ORIGINS OF THE KENT INTERLOBATE MORAINE, NE OHIO

Understanding the genesis of moraines is fundamental for understanding palaeo-ice sheet extent and dynamics. A complex set of moraines that were laid down by the Laurentide Ice Sheet during Late Wisconsinan deglaciation is present in North-east Ohio. These are mostly end and recessional moraines and have been studied in some detail by other researchers. The moraines of most interest are part of a complex here named the Kent Interlobate Complex. This interlobate complex was formed between the Grand River and Killbuck sublobes (part of the larger Erie lobe). The complex is approximately 75 kilometers long and runs from the center of Geauga County, through Portage County, to the southern parts of Stark County. The complex ranges from 11 kilometers to 21 kilometers wide and is easily identified on satellite imagery, air photographs, and Digital Elevation Models as a hummocky, pitted surface.

Several gravel pits are present in the interlobate complex, and each displays sorted, bedded sand with ripple lamination and cross bedding, and massive gravel units of glaciofluvial origin. This demonstrates that the interlobate complex is a primary glaciofluvial feature. White(1982) proposed that hummocky terrain in the studied area is primarily composed of kames and other ice-contact features. However when analyzing the sedimentology of the hummocks present in two sand and gravel pits it was possible to observe that they were composed of undisturbed glaciofluvial sediments that recorded several cycles of sedimentation. This rhythmicity in sedimentation is not a common characteristic of kame sedimentology. Therefore based on these sedimentary characteristics it is also proposed that hummocks in the studied area are not kames but large-scale glaciofluvial dunes that were deposited during the late Wisconsin period by large discharge events.

Recessional moraines situated south of the research area, and lacustrine clays found beneath the glaciofluvial sediments, also seem to indicate that the interlobate complex was deposited time-transgressively on a large proglacial outwash environment between two large glacial lobes and a large proglacial lake