The only formal morphostratigraphic units recognized in IL are units related to moraines that are called "drifts." Is named for the village of Hildreth, Edgar Co, IL (Illinois basin), 5 mi south of Sidell; is based on the Hildreth Moraine (mapped on pl. 1). Moraine is a weak ridge, only 20 to 25 ft high, and extends eastward from its contact with the Champaign Moraine south of Urbana for about 25 mi. From that point for about 25 mi farther eastward to the IN state line, it is a narrow but distinct ridge generally 40 to 50 ft high. It becomes much weaker again near the state line. It has previously been undifferentiated or included in the Champaign Moraine. It is much smaller than the massive Champaign Moraine, and its relation to that moraine is marked by the overlapping Urbana Moraine. Deposited by the Decatur Sublobe of the Erie Lobe. Assigned to Woodfordian Substage of Wisconsinan Stage in Pleistocene Series.

Source: GNU records (USGS DDS-6; Denver GNULEX).