PMF IAS Current Affairs
PMF IAS Current Affairs

Karst Landforms & Cycle of Erosion | Stalactite & Stalagmite

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Karst Landforms – Cavern, Arch/Natural Bridge, Sink Hole/Swallow Hole, Karst Window, Sinking Creeks/Bogas, Stalactite and Stalagmite.

Landforms and Cycle of Erosion

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.

Cavern

  • This is an underground cave formed by water action by various methods in a limestone or chalk area.

Cavern - karst landforms - karst cave

Arch/Natural Bridge

  • 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.

Sink Hole-Swallow Hole-karst landformsSink Hole-Swallow Hole-karst landforms

Karst Window

  • When a number of adjoining sink holes collapse, they form an open, broad area called a karst window.

Karst Window - karst landform

Sinking Creeks/Bogas

  • 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.

Sinking Creeks-Bogas-karst

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.

Stalactites - stalagmites karst landforms

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6 Comments

  1. SIR PLEASE EXPLAIN STALACTITE FORMATION. I AM UNABLE TO UNDERSTAND FROM THE TEXT. PLEASE EXPLAIN IN SOME DETAIL.

    • In a Karst Cavern (let us simply call it karst cave), when water seeps through the ceiling (upper part of the cave) it trickles drop by drop . Small amount of water drop evaporates even before falling down from the ceiling leaving behind very minute limestone particles (Take a look at these images: https://goo.gl/m0TKU0 & https://goo.gl/ZqaoVy). Over a period of time (few years) the process of evaporation continues as the limestone particles keep accumulating at to the ceiling forming a inverted cone like structure).

      This a common phenomenon that we observe in our daily lives. A leaky ceiling is the simple example (See image: https://goo.gl/O1JsM8)

  2. Sir, these geography notes are very helpful, appreciate your efforts. Please provide notes for history and polity also.

  3. Sir, these geography notes are very helpful, appreciate your efforts. Please provide notes for history and polity also.

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