They formed in 20 to 40 inches of silty material with less than 15 percent sand coarser than very fine sand and the underlying stratified loamy sediments. These are the competing Drummer soils and the Barrington , Brenton , Elburn , Harpster , Mundelein , Peotone , and Wauconda soils. Drummer soils are slightly higher on the landform and commonly are adjacent to or surround areas of Pella. The moderately well drained Barrington soils and somewhat poorly drained Mundelein soils are on higher parts of the landform and form a drainage sequence with Pella. The somewhat poorly drained Brenton and Elburn soils have argillic horizons, lack carbonates within a depth of 40 inches, and are on higher part of the landform.
Harpster soils are on similar or slightly lower parts of the landform and are calcareous throughout.
Peotone soils are on similar or slightly lower positions, have mollic epipedons more than 24 inches thick, and lack carbonates within a depth of 40 inches. Wauconda soils lack mollic epipedons and are on slightly higher parts of the landscape. Runoff is slow and in some places, ponded in late winter and spring or after snow melt or periods of excessive rainfall. The apparent seasonal high water table is at 0.5 foot above the surface to 1.0 foot below the surface during spring in most years. Permeability is moderate.