Coming along the cliffs from Boscastle towards Tintagel, at the part just seawards of the village of Trevalga, and between the outlying rocks known as “Short Island” and “Long Island,” we see one or two limited outcrops of a schistose rock different from the surrounding slates, shales, etc. A thoroughly good sight of it is not, however, obtained till we reach the extreme north side of Bossiney Cove, a little way south of Long Island, when a very fine exposure of the sheet in question is observed, lying in among the sedimentary rocks, sharply marked off from them at contact, so that the junction-lines can be seen distinctly even from some distance.