Treak Cliff Cavern

Treak Cliff Cavern is a show cave near Castleton in Derbyshire, England. It is part of the Castleton Site of Special Scientific Interest and one of only two sites where the ornamental mineral Blue John is still excavated (the other is the nearby Blue John Cavern). As part of an agreement with English Nature, the Blue John that can be seen in the show cave is not mined but it is extracted in small quantities from other areas of the cave and made into saleable items like bowls, jewellery, and ornaments. The cave comprises three sections, the Old Series, discovered by lead miners in the 18th century, the New Series, discovered during blasting in the 1920s, and the New Series Extensions, discovered in 2014. Only the Old Series contains Blue John, but the New Series is well decorated with flowstone, stalagmites, and stalactites. The New Series Extensions are also highly decorated, but are only accessible by experienced cavers. Three human skeletons and flint implements from the Neolithic era were found in a small cave nearby in 1921.