A New Map of Pleistocene Proglacial Lake Tight Based on GIS Modeling and Analysis

Abstract

Glacial-age Lake Tight was first mapped by John F. Wolfe in 1942. Wolfe compiled his map from photographs of 50 USGS topographic maps, and used the 900-foot contour to delineate its shoreline. An estimate, as reported by Hansen in 1987, suggested an area of approximately 18,130 km2 (7,000 mi2) for the lake. Using a geographic information system (GIS) environment, an updated map of Lake Tight was developed employing the 275-meter (902-foot) elevation contour. Calculations now suggest the area of Lake Tight was 43 percent larger or approximately 26,000 km2 (10,040 mi2) and the volume approximately 1,120 km3 (268 mi3). The reconstruction of Lake Tight in a GIS creates a spatial analysis platform that can support research on the origin and development of the lake, the geologic processes that occurred as a consequence of the advance of the pre-Illinoian ice, and the origin of the Ohio River. The development of the upper Ohio Valley during the Quaternary Period remains one of the outstanding problems in North American geology. The details of the transition from the Teays River to Lake Tight, and from Lake Tight to the Ohio River, are poorly understood despite more than 100-years passing since the first significant study of those changes. A refined understanding of the area and depth of Lake Tight is essential but is complicated by fundamental unknowns—such as the location of the pre-Illinoian ice margin and the extent and consequence of isostatic flexure of the lithosphere due to ice-loading and lake-loading. Given the assumptions required for the model, the accuracy of both the raster data and the 1942 topographic maps, and the paucity of essential field data, mapping the lake shoreline at the widely cited 274.32-meter (900-foot) contour would not provide increased verifiable accuracy.