What is Limestone?
Erosion of Limestone
Limestone (Karst) Features - overview
Limestone features above ground
Limestone features below ground
Limestone and Recreation
Case Study - Malham, The Yorkshire Dales

What is Limestone?

Limestone is an organic, sedimentary rock. This means it was formed from the remains of tiny shells and micro-skeletons deposited on the sea bed. They were compressed to form solid rock. Limestone is made up of calcium carbonate and reacts with diluted hydrochloric acid. Limestone is formed in layers - called bedding planes. These bedding planes contain vertical cracks called joints. Joints and bedding planes make the rock permeable.

Erosion of Limestone

Weathering is the breakdown of rock by physical, chemical or biological processes. Limestone areas are weathered when rainwater, which contains a weak carbonic acid, reacts with limestone. When it rains limestone is dissolved. Rainwater erodes the joints and bedding planes. In doing this Karst scenery is created.

Limestone (Karst) Features - overview

Limestone (Karst) Features - above ground

Karst scenery includes:

Swallow hole - An exposed limestone joint down which a surface river 'disappears'.

Clints and grykes - Rainwater flowing over an impermeable surface will, on reaching (permeable) limestone, be able to dissolve the joints into grooves called grykes, leaving blocks or clumps of limestone in between called clints

Limestone pavements - Exposed clints and grykes.

Limestone (Karst) Features - below ground

Stalactite - Water dripping from the roofs of caves leave behind microscopic particles of calcium carbonate. These build up as icicle shaped stalactites.

Stalagmite - Drips splashing onto the cave floor create stalagmites.

Limestone and Recreation

Limestone areas offer a wide range of opportunities to recreationists. This includes - pot holing, caving, walking, climbing, abseiling and many other outdoor pursuits.