Black Hawk county is located in northeastern central Iowa, in the fourth tier of counties south of the Minnesota state line and in the fourth tier west of the Mississippi river. It is in the Iowan drift soil area and hence the major portion of its soils are glacial in origin. Much of the county has been covered by loess deposits, however, and the soils on a considerable area are mapped as loessial.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 14—Black Hawk County" (1920). Soil Survey Reports. 20.