United States Map 1931 Soil Materials Print - Upper Midwest, Mississippi Valley, Appalachians

Francis J. Marschner compiled this Parent Materials of Soils map, Soils Plate 4, for the U.S. Department of Agriculture's Atlas of American Agriculture, engraved by A. Hoen & Co. and printed in Washington as part of a federal reference on the country's land, climate, soils, and vegetation prepared under O.E. Baker of the Bureau of Agricultural Economics. Drawn in 1931 and finished in full color, the sheet classifies American soils not by their surface character but by the geological processes that formed them, distinguishing unconsolidated deposits such as glacial drift and river alluvium from residual materials weathered in place from limestone and sandstone bedrock. The atlas as a whole was compiled during the early 1930s, part of a broader federal push to understand the country's farmland scientifically rather than by regional folklore.

The upper Midwest and Northeast carry the glacial-drift classification across most of their surface, ground scraped and redeposited by ice sheets that retreated only a few thousand years before European settlement. The Mississippi and other major river valleys are marked as alluvial, soil built up from centuries of flooding and sediment deposit that made them among the most fertile farmland in the country. The Appalachians and much of the interior South carry residual classifications, soil formed slowly in place from the weathering of the bedrock beneath it. Together the three parent-material types describe a geological explanation for the same regional soil patterns shown on the companion Great Soil Groups sheet.

For anyone drawn to earth science rather than agriculture alone, this sheet's focus on how soil itself came to exist in a given region makes it a distinctive gift, and it suits a collector or student of American geology and land history just as well. The store also carries six companion sheets from the same Atlas of American Agriculture, covering great soil groups, natural vegetation, physical features, average annual precipitation, summer temperatures, and last spring frost dates; this sheet is the only one in that set tracing soil back to its geological origin rather than its present classification. It's printed unframed and available in a range of sizes to fit whatever wall it's headed for.