A Procedure for Projecting And Correlating Ice-Margin Positions

Abstract

Recognition and correlation of ice-marginal positions on the Appalachian Plateau is based on the distribution of depositional landforms. Valley floors provided a much more conducive environment for glacial deposition than did adjacent valley slopes and divides, where ice-marginal landforms are poorly developed if preserved at all. The projection of a glacier surface from a mapped valley position serves to direct attention to divide areas in which subtly expressed ice-marginal landforms are most likely to be found. The projection technique involves a graphic method for placing a hypothetical glacier lobe at a known valley position and projecting its surface gradient onto contiguous valley slopes in order to trace the trend of the ice margin across the landscape. The technique was field tested in areas of documented ice-marginal trends and found to be valid for general use. Essential items include topographic map coverage (1:24,000), a Quaternary map, and water-well data from which depth to bedrock can be i...