Gravel content ranges from 15 and 70 percent. Sand content ranges from 75 to 98 percent. These are the Chalmers , Chetomba , Dolbee , Drummer , Elpaso , Elvira , Garwin , Hartsburg , Madelia , Mascoutah , Maxcreek , Maxfield , Ossian , Patton , Pella , Rushmore , Sable , and Wacousta series. All competing series except the Rushmore series contain less than 15 percent rock fragments in the lower part of the series control section. Rushmore soils average less than 75 percent sand in the lower part of the series control section.
Dunham soils are in depressions or on nearly level parts of outwash plains and stream terraces.
Slope gradients range from 0 to 2 percent. Dunham soils formed in 24 to 50 inches of loess or other silty material and in the underlying loamy outwash over sandy and gravelly deposits. The associated soils are on higher positions on the landform. The somewhat poorly drained Grundelein and well drained Waupecan soils form a drainage sequence with Dunham soils. The well drained Bowes and Rush soils and somewhat poorly drained Millstream soils do not have mollic epipedons.