Rozetta, Ruma, and Stookey soils average less than 7 percent sand throughout the particle size control section. Westbend soils have a lithic contact with shale between 40 and 60 inches. Rush soils have more than 10 percent gravel in the lower part of the control section. Westmore soils have more than 5 percent shale and sandstone fragments in the lower part of the control section. Yellowriver soils average more than 10 percent sand in the surface and upper part of the particle size control section and less than 10 percent sand in the lower part of the series control section.
Ridgway soils are on outwash plains, stream terraces, and high flood plains.
They are thought to be of late Wisconsinan Age. Slope gradients are between 0 and 10 percent. These soils formed in 24 to 40 inches of loess or other silty sediments and in loamy or sandy outwash. In the area of the typifying pedon the lower part of the solum formed in sandy outwash that has eluvial E layers and illuvial Bt lamella. Mean annual temperature ranges from 54 to 57 degrees F, and the mean annual precipitation ranges from 40 to 48 inches.