Gypsum

Karst in gypsum (hydrated calcium sulphate) is present mainly in the Permian rocks of eastern and north-eastern England, particularly around Ripon and Darlington, and in the Vale of Eden. Gypsum karst also occurs locally in the Triassic strata in the Midlands, but the effects here are much less severe than in the Permian rocks.

Collapse of four garages into subsidence caused by the dissolution of gypsum at Ripon, North Yorkshire.
Collapse of four garages into subsidence caused by the dissolution of gypsum at Ripon, North Yorkshire.

Gypsum karst can form water-filled cave systems, but the rapid solubility rate of the gypsum means that the karst is evolving on a human time scale. Active subsidence occurs in many places, especially around the town of Ripon. The active nature of the dissolution and the ongoing subsidence features cause difficult conditions for planning and development.

Massive Permian gypsum at Ripon Parks, North Yorkshire. The river has dissolved the gypsum, creating a deep undercut at the base of the cliff. Soon after this photograph was taken in 1989 the cliff collapsed.
Massive Permian gypsum at Ripon Parks, North Yorkshire. The river has dissolved the gypsum, creating a deep undercut at the base of the cliff. Soon after this photograph was taken in 1989 the cliff collapsed.

Further reading