Which one of the following karst landforms is the largest in size?

The correct answer is Polje.

Key Points

• Karst Landforms-
  • Karst is a landscape which is underlain by limestone which has been eroded by dissolution, producing towers, fissures etc.
  • A Polje Karst is a large flat plain found in karstic geological regions of the world, with areas usually 5–400 km².
  • A polje or karst polje covers the flat bottomed lands of closed basins which may extend over large areas.

Additional Information

• Karst is a distinctive topography in which the landscape is largely shaped by the dissolving action of water on carbonate bedrock such as limestone and dolomite etc.
• When the rain falls through the atmosphere, it picks carbon dioxide which dissolves in the droplets.
• Once the rain hits the ground, it percolates through the soil and picks more carbon dioxide to form a weak solution of carbonic acid.
• The infiltrating water naturally exploits cracks in the rock.
• Over long periods, carbon bedrock begins to dissolve.
• Opening in bedrock increases in size and an underground drainage system begins to develop and allows more water to pass which further accelerate the formation process of karst.
• Some of the landforms develop within the bedrock such as pools, sinkholes, doline, stalactites, stalagmites etc.
• Certain other features of Karst are:
  • Solution flutes (or rillenkarren)
  • Runnels
  • Limestone pavement (clints and grikes)
  • Sinkholes or cenotes (closed basins)
  • Vertical shafts
  • Foibe (inverted funnel-shaped sinkholes)
  • Disappearing streams
  • Reappearing springs
  • Limestone pavements
  • Karst valleys