Castleton, Derbyshire in the context of Civil parish

Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope movement.

Processes that lead to subsidence include dissolution of underlying carbonate rock by groundwater; gradual compaction of sediments; withdrawal of fluid lava from beneath a solidified crust of rock; mining; pumping of subsurface fluids, such as groundwater or petroleum; or warping of the Earth's crust by tectonic forces. Subsidence resulting from tectonic deformation of the crust is known as tectonic subsidence and can create accommodation for sediments to accumulate and eventually lithify into sedimentary rock.

Peakshole Water is a stream in the Derbyshire Peak District of England, named after its source, Peak Cavern. It flows through the village of Castleton to join the River Noe in nearby Hope. Despite its name, much of its flow actually emerges from the Russet Well, a resurgence in a garden on the east side of the gorge below the main Peak Cavern entrance, described as the "main resurgence of the Castleton area", which drains a series of swallets on the other side of the Pennine watershed below Rushup Edge. The resurgence has been explored by cave divers to a depth of 82 feet (25 m) but further exploration was halted by a constriction.

The River Noe flows into the Derbyshire Derwent, which in turn leads to the River Trent and thence to the Humber estuary and the North Sea.

Blue John (also known as Derbyshire Spar) is a semi-precious mineral, a rare form of fluorite with bands of a purple-blue or yellowish colour. In the United Kingdom it is found only at Blue John Cavern and Treak Cliff Cavern at Castleton in Derbyshire. During the 19th century, it was mined for its ornamental value, and mining continues on a small scale.

In engineering, shear strength is the strength of a material or component against the type of yield or structural failure when the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force. When a paper is cut with scissors, the paper fails in shear.

In structural and mechanical engineering, the shear strength of a component is important for designing the dimensions and materials to be used for the manufacture or construction of the component (e.g. beams, plates, or bolts). In a reinforced concrete beam, the main purpose of reinforcing bar (rebar) stirrups is to increase the shear strength.

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.