The low, but rocky headland of Dwlban Point forms the western corner of Red Wharf Bay, on the east coast of Anglesey; and is on the coastline of the principal tract of Carboniferous rocks in the island, not very far from the boundary fault which runs out to sea beneath the sands of the bay. The Carboniferous Limestone near the Point is for the most part a light-grey, crystalline rock, with abundant crinoids, corals, and other marine fossils. There are, however, four beds of sandstone, varying from 2 to 9 feet thick, and some of the Limestone itself also contains scattered grains of quartz. The sandstones are clean white rocks, generally fine, but with occasional thin seams of small pebbles.