Louisa County is located in southeastern Iowa, bordering the Mississippi river, and in the third tier of counties north of the Missouri state line. It is partly in the Mississippi loess soil area and partly in the southern Iowa loess soil area. All the upland soils of the county are therefore loessial in origin and the terrace and bottomland soils are likewise derived from loess.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 21—Louisa County Soils" (1921). Soil Survey Reports. 31.