The cliffs of Carmel Head are made of Precambrian gneiss -- coarsely banded metamorphic rock, dark and grey, with layers folded and bent by heat and pressure over geological time. These are almost certainly the oldest rocks in Wales, formed at least 700 million years ago and possibly much earlier. They were then pushed up and over younger Ordovician rocks along a structural feature now called the Carmel Head Thrust -- a major geological fault that moved a slice of ancient continental basement onto top of younger sea-floor sediments. The geology is so important that the whole headland is designated a Site of Special Scientific Interest. To stand on the cliffs and look down at the gneiss is to stand on stone that was already very old when the first complex life began. The headland peaks at just 81 metres, which is modest by the standards of Welsh hills, but the rock under your feet is anything but.

Off the head lie the Skerries -- a low, rocky archipelago about a mile offshore, with a famous lighthouse on the main island that has been guiding ships into and out of Liverpool, Dublin, and Holyhead since 1717. Closer in are three smaller islands, the Mouses: West Mouse, Middle Mouse, and East Mouse, lined up east to west along the coast. The columns of the Three White Ladies were placed in the 1860s in a specific geometric relationship to West Mouse: lining up the column on West Mouse with the two columns on Carmel Head gives you the bearing of a shallow reef that lies underwater between them. From a sailor's deck at sea level, the columns are visible against the cliffs, and the alignment can be checked in a glance. The columns are unlit and crude by modern lighthouse standards. They are also still working today, the only navigation aids on this particular hazard that ships need.

The history of Carmel Head reads like a maritime ledger of the nineteenth and twentieth centuries. 1829: the brigantine Brown of Whitehaven ran aground with a cargo of cattle; the captain drowned, the cargo was saved. 1854: the Mersey flat John and Mary went onshore at Carmel Point and was flooded by the tide; her crew were saved. 1885: the four-masted ship The Earl of Chatham wrecked here; her crew also saved. 1886: the sailing ship James Kenway, bound from Liverpool to Charleston with cargo, foundered on the rocks; two of her crew drowned. 1890: the Swedish barque Hudiksvall broke her tow line and went up on Carmel Point. 1898: the schooner City of Chester was wrecked on the west side of the head. 1913: the steam trawler Lorwoone ran aground in fog; her captain swam ashore and walked three miles into Holyhead to fetch the lifeboat, which came back and recovered her. 1939: the liner Hilary, inbound from Brazil to Liverpool, ran aground at the head; a hundred passengers were taken off by lifeboat, and the ship refloated under her own power. 1953: the steamer Larchfield was holed on the rocks, refloated and beached, and later returned to service. The reef has not stopped working.

In the early nineteenth century, the Great Carmel's Points copper mine -- also called the Gadair Mine, from Trwyn y Gadair, the Welsh name for the head -- was opened on the slope. The miners hoped they had found an extension of the rich copper vein at Parys Mountain a few miles east, which was at the time the largest copper mine in the world. They had not. The mine was only about 170 feet deep but ran galleries 1,500 feet inland following a vein 30 feet wide. Six vertical shafts connected the levels to the surface. The ore quantities never met expectations. The mine was abandoned around 1880, and its equipment -- a 30-horsepower beam engine, the boiler, the pumping and winding gear -- was sold off in 1883. The ruins of the engine house, offices, and a tall chimney stack still stand on the headland today, weathered and increasingly merged with the cliffs they were built into. The Anglesey Coastal Path passes through them in summer; in winter the head is closed to walkers for pheasant shooting on the National Trust land that covers most of the cliff.