Shows soil types classification by colors and symbols. 'Field operations Bureau of Soils.' Scale 1:63,360. 1 inch = 1 miles. U.S. Dept. of Agriculture, Bureau of Soils; Purdue University, Agricultural Experiment Station; Soils surveyed by Mark Baldwin and J.A. Slipher, U.S. Dept. of Agriculture and S.C. Jones, Purdue University Agricultural Experiment Station.