The shore of the Menai Straits on the Carnarvonshire side, nearthe Suspension Bridge, is composed, as is well known, ofsandstones and shales belonging to the Carboniferous Series. Abouta quarter of a mile west of the bridge, however, some fissile, reddishand greenish shales appear on the foreshore, dipping at higherangles than usual. This might easily be ascribed to local disturbance, as a large fault is not far off, though the shale differs somewhat from that which is common in the Carboniferous rocks of the district, a fact which was noticed by Mr. G. H. Morton, who went with me along this part of the section.