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Erosion

Limestone landscapes

Karst landscape, FranceKarst landscape, France Limestone, a type of sedimentary rock, consists of the remains of tiny sea creatures that lived millions of years ago. It is made of calcium carbonate, a substance that dissolves easily in water. Because of this, limestone landscapes, also known as karst topography (from the landscape around the Kras Plateau in Slovenia), have a number of distinctive features. These include caves, pavements, swallow holes and dry valleys.


Clints and grykes on a limestone pavementClints and grykes on a limestone pavement

Limestone pavements

Natural cracks or joints in the limestone criss-cross the surface. These are gradually widened by water dissolving the rock to form a limestone pavement. The raised lumps are called clints, and the eroded cracks are called grykes.



Karst topography and its typical featuresKarst topography and its typical features

Swallow holes

Large, vertical holes in the limestone are called swallow holes or sink holes. These are formed by the the rock being dissolved or worn away by water, or by the collapse of a cavern roof. When the stream no longer flows, the swallow hole becomes a dry pot hole.


Stalactites, stalagmites and a columnStalactites, stalagmites and a column

Caves

Highly eroded karst landscapes in which steep-sided hills are set in flat river floodplains are called tower karst and are a famous feature of the Guilin area in south China.

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