Vol. 43, No. 1, Spring/Summer 2005- "The Pennsylvania Geographer"

MODELING THE EFFECTS OF GLACIAL ISOSTASY ON STREAM TERRACE FORMATION

Brent J. Zaprowski

Joshua Floyd

Department of Geography and Geosciences

Salisbury University

Salisbury, MD

Abstract

Field studies of streams and stream terraces in the northern High Plains show that the area has undergone several phases of base level adjustment during the Pleistocene resulting in the formation of multiple terraces in those drainage basins. It was hypothesized that the streams were responding to crustal adjustments caused by the advance and retreat of nearby continental ice sheets. Using a hinged stream table, experiments were run to see if glacial isostacy could cause permanent base level lowering and stream terrace formation. These experiments successfully demonstrated that downwarping of a stream can lead to base level change and terrace formation. Although several design factors may have played a role in the results, it is believed that the results of these experiments show that glaciers can affect landscapes in non-glaciated areas adjacent to glaciated areas through the formation and migration of knickpoints.