Limestone reef, Derbyshire

Image to left: shelly limestone

This limestone cliff shown at the base of this page is made up of the remains of corals, crinoids and shells that formed a reef within a tropical lagoon that covered much of the Peak District around 325 million years ago.

Thinner layers of limestone, formed as carbonate mud, surround and cover the hump-like reef structure that now forms a cliff above the river Derwent, and is popular

Derrick Clements, www.heathbank.co.uk