Martinsburg soils have thicker E horizons. Minnith soils commonly have thinner sola, are formed in residuum from sandstone, and are commonly more yellow. Flagg soils are on gently sloping to strongly rolling till plains and moraines. Slope gradient ranges from 0 to 20 percent. These soils formed in 30 to 50 inches of loess and late Sangamon paleosols formed in sandy loam, loam, or clay loam Illinoian till.
Summers are hot and winters are cold.
Mean annual temperature is between 45 and 57 degrees F, and mean annual precipitation ranges from 28 to 40 inches. These are the Myrtle , Ogle , Pecatonica , and Westville soils. The Myrtle and Ogle form a biosequence with the Flagg soils. The well drained or moderately well drained Pecatonica and Westville soils have thinner mantles of loess than Flagg soils. Permeability is moderate.