Interglacial Intervals

In this photo, taken at Tuscola Quarry in central Illinois, tills of three glacial episodes (from top down, Wisconsin, Illinois, and pre-Illinois) and three interglacial soils (modern, m; Sangamon, S; Yarmouth, Y) can be seen along with a preglacial soil developed in bedrock. The soil B horizons are oxidized to an orange-brown hue and soil A horizons are lacking, except for in the modern soil, which is buried beneath spoil material from the quarry pit.