A petrographic study of the pre-Cambrian of Kansas

Many wells have penetrated the pre-Cambrian surface along the "granite ridge" and elsewhere in Kansas. Microscopic examination of cuttings from wells which have gone some distance into the ancient crystallines confirms the idea that the Kansas pre-Cambrian rocks compose a metamorphic complex, mainly gneiss and schist, rather than granite. Some wells have gone directly from the sedimentary rocks into schist, but the pre-Cambrian rocks have not been recognized as such until a much deeper granite (probably gneiss) was struck.