Illite is the dominant clay material in the Hagerstown, Laidig, and Leck Kill soils, but weathering has produced some vermiculite in the surface layer. Kaolinite is the dominant clay mineral in the Morrison soils, and the other soils have only a small amount of kaolinite. Kaolinite clay is associated with the parent rock and is not the result of present weathering. Other soils, such as Hublersburg soils, can have a moderate to large amount of kaolinite where developed from the same geologic formation as the Morrison soil. An interstratified vermiculite-illite complex is in surface horizons of all four soils. Chlorite was present in only trace amounts.

10/15/98