The southern part of this parish includes the whole of the granite of
Kit Hill, which is for the most part of the coarse-grained crystalline
variety so common in Cornwall. Proceeding northward, the rest of the
parish is found to belong to the schistose rocks; those next to the
granite are felspathic, and contain beds of porphyry, but those more
remote, which form the greater part, must be referred to the
calcareous series.