Karst Landforms – Cavern, Arch/Natural Bridge, Sink Hole/Swallow Hole, Karst Window, Sinking Creeks/Bogas, Stalactite and Stalagmite.
Landforms and Cycle of Erosion
- Fluvial Erosional Landforms [Done]
- Fluvial Depositional Landforms [Done]
- Glacial landforms and Cycle of Erosion [Done]
- Marine landforms and Cycle of Erosion [Done]
- Arid landforms and Cycle of Erosion [Previous Post]
- Karst landforms and Cycle of Erosion [This Post]
Karst Landforms and Cycle of Erosion
- Karst is a landscape which is underlain by limestone which has been eroded by dissolution, producing towers, fissures, sinkholes, etc.
- It is so named after a province of Yugoslavia on the Adriatic sea coast where such formations are most noticeable.
- Karst topography is a landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum.
- It is characterized by underground drainage systems with sinkholes, caves etc..
Conditions Essential for Full Development of Karst Topography
- Presence of soluble rocks, preferably limestone at the surface or sub-surface level.
- These rocks should be dense, highly jointed and thinly bedded.
- This is an underground cave formed by water action by various methods in a limestone or chalk area.
- When a part of the cavern collapses the portion which keeps standing forms an arch.
Sink Hole/Swallow Hole
- Sink holes are funnel-shaped depressions having an average depth of three to nine metres.
- These holes are developed by enlargement of the cracks found in such rocks, as a result of continuous solvent action of the rainwater.
- The surface streams which sink disappear underground through swallow holes.
- When a number of adjoining sink holes collapse, they form an open, broad area called a karst window.
- In a valley, the water often gets lost through cracks and fissures in the bed. These are called sinking creeks, and if their tops are open, they are called bogas.
Stalactite and Stalagmite
- The water containing limestone in solution, seeps through the roof in the form of a continuous chain of drops.
- A portion of the roof hangs on the roof and on 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 to the floor. This also evaporates, leaving behind a small deposit of limestone aiding the formation of a stalagmite, thicker and flatter, rising upwards from the floor.
- Sometimes, stalactite and stalagmite join together to form a complete pillar known as the column.