KARST OR LIMESTONE TOPOGRAPHY

KARST OR LIMESTONE TOPOGRAPHY
In dry regions, mainly in highlands composed of limestone-like rocks on a large scale, 'karst' topography is caused by the movement of underground water as an agent of gradation. It is so named after a province of Yugoslavia on the Adriatic Sea coast where such fOrmations are most noticeable. Karst is a region of well-jomted carboniferous limestone in which carbonation is the domi­nant weathering process. Carbonation in the karst region produces features such as sink hole, swallow holes, and caves or caverns (a large cave is called a cavern). The most striking features of caves are stalactites and stalagmites.

Sink Holes Sink hole is a funnel-shaped depression which has an average depth of three to nine metres and in area, it may vary from one square metre to more. In the limestone plateau of Kentucky in the USA, the number of sink holes is well over 60,000.
Swallow Holes Swallow holes are cylindrical in shape lying underneath the sink hole. These holes swallow the sub-surface streams which may re-appear from rock open­ings.

Caves or Caverns A cave is an underground chamber that is accessible from the surface. Caves are most fre­quently found in cliffs along coasts and in limestone areas. In limestone regions, caves are the result of the rock being dissolved through carbonation by underground streams. The water seeps through the roof of the caverns in the form of a continuous chain of drops. A portion of the drop hangs on the roof and on the evaporation of water, a small deposit of limestone is left behind contributing to the formation of a stalactite, growing downwards from the roof. The remaining portion of the drop falls on the floor of the cavern. This also evaporates and forms a stalagmite, rising upwards from the floor.
Stalactites and stalagmites often meet to merge into a column.