This coverage outlines the boundary of the Loess Hills in Iowa at 1:100,000 scale. Criteria applied to the delineation of the Loess Hills included drainage density, drainage divides, density of isolated hillforms, crenulated contours, slopes greater than 15%, presence of catstep features, general loess thickness and earlier mapping. The following sources were utilized: 1:100,000 and 1:24,000 scale USGS topographic maps, USDA-NRCS STATSGO Soil Survey Grid Information, Digital Elevation Module, and the 1:2,000,000 Landforms of Iowa Coverage.
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