The Knowles series consists of well drained soils moderately deep to dolomitic limestone. These soils are on ground moraine and formed in loess and the underlying glacial till.
Permeability is moderate.
Slopes range from 0 to 30 percent. Knowles silt loam - on a 4 percent slope in a cultivated field at an elevation of about 893 feet. The solum thickness ranges from 20 to 40 inches and rests on dolomitic limestone. The loess thickness typically ranges from 18 to 30 inches but in some pedons it is as thick as 36 inches. In the 2B horizon, pebbles range from 0 to 10 percent by volume and cobbles from 0 to 2 percent by volume.