This is one of the geological and scenic highlights of the Peak District National Park. Alport Castles is said to be the largest landslip in Britain, but it is rarely visited because of its remoteness.
The Alport Valley is made up of weak Carboniferous shales (fine-grained rocks made of mud) overlain by harder Millstone Grit. The large cliff face we see here is the Birchin Hat escarpment. Alport Castles formed when the softer sandstones and shales of Birchin Hat slipped away from the rock-face. The Millstone Grit on the top broke up into blocks and tumbled down the valley side, creating a chaotic landscape of fallen boulders. With a little imagination, they can resemble castles – hence the name.