Guthrie County is located in the west central part of Iowa, in the fourth tier of counties north of the Missouri state line and in the fourth tier east of the Missouri River. It is partly in the Wisconsin drift soil area and partly in the Mississippi loess, the Missouri loess and the Southern Iowa loess soil areas. The soils are, therefore, partly of glacial origin and partly of loessial origin, loess types representing all three loess areas occurring in the county.
Brown, P. E.; Orrben, C. L.; Meldrum, H. R.; and O'Neal, A. M., "Soil Survey of Iowa, Report No. 75—Guthrie County Soils" (1935). Soil Survey Reports. 77.