Warren County is located in south central Iowa in the third tier of counties north of the Missouri line and is in the fifth tier of counties east of the Missouri River. It is partly in the Mississippi loess and partly in the Southern Iowa loess soil areas, and the soils of the county are mainly of loessial origin. There is, however, a considerable acreage of drift soils such as are found thruout the Southern Iowa loess soil area. These drift soils are derived from the Kansan till underlying the loessial deposits in southern Iowa.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 62—Warren County Soils" (1930). Soil Survey Reports. 58.