Identification of Mapped Ice-Margin Positions in Western New York from Digital Terrain-Analysis and Soil Databases

Abstract

Geographic Information Systems (GIS) are rarely applied to problems associated with Wisconsinan ice-margins. This study identifies inconsistencies in ice extent in the Salamanca Re-entrant in western New York as mapped using soil properties and surficial geology. In essence, previous studies have revealed a zone of disagreement between those areas that were clearly glaciated and those that were not. This study uses a raster-based approach to extract the soil pH, silt, and clay contents from digital soil databases; and the morphometric parameters of elevation, slope, terrain ruggedness, and planform and profile curvature from mosaiced 10-m digital elevation models. Two-way ANOVA indicates a close correspondence between the zone of disagreement and the glaciated area when soil information is used; however on the basis of morphometry, the area of disagreement is analogous to the unglaciated terrain. These results highlight both previous difficulties and the source of the mapped differences, suggesting that a GIS analysis of former ice margins is a productive preliminary step to their precise delineation.