Physiography of the Des Moines Lobe GIS Data
Author: Bradley Miller
This GIS package includes two spatial datasets developed to support physiographic and geomorphic studies of the Des Moines Lobe region in north-central Iowa. The first is a surficial geology raster derived from the USDA-NRCS gSSURGO database, representing parent materials to a depth of 2 meters. The second is a vector dataset delineating physiographic regions within the Des Moines Lobe, defined by major moraines and associated topographic and geologic differences.
Interpretation Method
The surficial geology raster was created by extracting attributes from NRCS Official Soil Series Descriptions (OSD), supplemented by additional interpretation based on soil profile properties and spatial context. The physiographic region boundaries were developed by identifying and mapping distinct landform surfaces, particularly those associated with prominent moraines and glacial history.
Applications and Visualization Tips
This dataset is well suited for analyzing landscape evolution, glacial geomorphology, soil genesis, and land use planning in the Des Moines Lobe region. For optimal visualization, overlay the data on high-resolution digital elevation models (DEMs) from the USGS to emphasize terrain–geology relationships.
Resolution and Coverage
Surficial geology raster: 10-meter resolution
Physiographic regions: vector delineation
Geographic extent: Des Moines Lobe and surrounding landform regions in Iowa
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GIS Map Details
This raster is a highly detailed map of geologic materials at the surface (delineations made from maps at 1:24,000 to 1:12,000 scale). The smaller extent maps were merged together by USDA-NRCS to produce the gSSURGO spatial database, covering the entire state at a 10m resolution. The gSSURGO map was then interpreted by Iowa State University’s Geospatial Laboratory for Soil Informatics (GLSI) for parent material, which is equivalent to the geologic material to a depth of 2 meters from the surface. Surficial material attributes were extracted from the NRCS official soil series descriptions (OSD), but at times some additional interpretation was needed based on typical soil profile properties and spatial relationships with better-defined soil series. Because of the common relationship between surficial geology and topography, digital elevation models would be complementary to this data set. Draping this surfical geology data set over hillshades derived from fine resolution elevation data works especially well.
References
Miller, B.A., C.L. Burras, W.G. Crumpton. 2008. Using soil surveys to map Quaternary parent materials and landforms across the Des Moines Lobe of Iowa and Minnesota. Soil Survey Horizons 49(4):91-95. doi:10.2136/sh2008.4.0091
Soil Survey Staff. 2014. Official Soil Series Descriptions (OSD). United States Department of Agriculture, Natural Resources Conservation Service. https://soilseries.sc.egov.usda.gov/osdname.asp
Soil Survey Staff. 2014. Gridded Soil Survey Geographic (gSSURGO). United States Department of Agriculture, Natural Resources Conservation Service. http://datagateway.nrcs.usda.gov
Miller, B.A. and C.L. Burras. 2015. Comparison of surficial geology maps based on soil survey and in depth geological survey. Soil Horizons 56(1). doi:10.2136/sh14-05-0005.
Soil Survey Staff. 2014. Official Soil Series Descriptions (OSD). United States Department of Agriculture, Natural Resources Conservation Service. https://soilseries.sc.egov.usda.gov/osdname.asp
Soil Survey Staff. 2014. Gridded Soil Survey Geographic (gSSURGO). United States Department of Agriculture, Natural Resources Conservation Service. http://datagateway.nrcs.usda.gov