Jasper County is located in central Iowa in the fourth tier of counties north of the Missouri state line and in the fifth tier west of the Mississippi River. It lies mainly m the Mississippi loess soil area. A small part of the county, however, is covered by soils derived from the Southern Iowa loess and from the Wisconsin drift. By far the largest portion of the soils of the county are of loessial origin.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 42—Jasper County Soils" (1926). Soil Survey Reports. 35.