Loess Distribution in Southeastern Illinois and Southwestern Indiana

Abstract

AbstractTotal loess (predominantly Peorian loess) thickness in southeastern Illinois and southwestern Indiana ranged from somewhat less than 40 inches to more than 300 inches, and the thinning rate of the loess was a linear function of the logarithm of the distance from the source. Peorian loess was present throughout the area, but Farmdale loess was present in significant amounts only in extreme southern Illinois and in extreme southwestern Indiana. Loveland loess was present sporadically beyond the limit of Illinoian glaciation. In the Wabash basin, loess thickens to the south as the valley becomes wider, the loess‐receiving landscapes become older, and the sediments in the valley become more silty. West‐northwest winds were important in the loess deposition of this region, but deposition of loess by easterly and southwesterly winds in the lower Wabash and Ohio river basins was shown to be more important than has been previously noted.