Complex sentence: All six of these formations are primarily composed of quartzite and argillite, with some limestone and dolomite occurring in the Wallace and Prichard, and a smaller amount of carbonate in the St. Regis.
Split into simpler sentences: All six of these formations are primarily composed of quartzite and argillite. Some limestone and dolomite also occur in the Wallace and Prichard, and a smaller amount of carbonate occurs in the St. Regis.