DIFFERENCES IN RESOLUTION AND GEOMORPHOLOGICAL INTERPRETATION BETWEEN SSURGO SOIL MAPS AND LEGACY GLACIAL GEOLOGY MAPS, ASHTABULA AND TRUMBULL COUNTIES, OH

The Ohio Department of Natural Resources, Division of Geological Survey is currently mapping surficial materials in three dimensions for the Ashtabula and Youngstown 1:100,000-scale quadrangles. The maps are to be used for ground-water management, land-use planning, mineral exploration, and geohazard susceptibility. Mapping is based on parent-material interpretations from NRCS SSURGO (Soil Survey Geographic) digital soil surveys (1:24,000 scale), boring data from water wells and highway corridor investigations, legacy maps of bedrock topography, bedrock geology, glacial geology, and digital elevation models. The end product is a two-dimensional GIS polygon layer with three-dimensional layer (“stack”) information attached as digital tabular files. Parent-material base maps (interpreted from SSURGO data) were compared to the glacial-geology maps in Ashtabula County (White and Totten, 1979) and Trumbull County (White, 1971) Ohio to investigate differences in resolution and interpretations. SSURGO appears to offer more detailed spatial information on surface materials due to increased mapping resolution. Marked differences in interpretation of surface material type were also noted. For example, an extensive area of glaciolacustrine deposits in the Newton Falls and Warren quadrangles is indicated from SSURGO data but is not present on the glacial-geology map. Field investigations are being planned to resolve interpretive differences between the maps.