Clayton County is located in northeastern Iowa in the second tier of counties south of the Minnesota state line and is separated by the Mississippi River from Wisconsin on the east. It is partly in the Iowan Drift and partly in the Mississippi loess soil areas, and the soils are, therefore, of loessial and glacial origin.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 65—Clayton County Soils" (1930). Soil Survey Reports. 55.