Karst Topography [UPSC Geography Notes]

Karst Topography is the formation of landforms due to solution and deposition on any limestone or dolomitic region by the action of groundwater or surface water. Landforms and its evolution is an important segment of the Geography syllabus of the IAS Exam.

Read relevant facts about Karst landforms for the UPSC preparation.

What are the features of Karst Topography?

The features of Karst Topography are listed down below:

  1. Swallow Hole in Section – When the stream of groundwater/surface water disappears in the hole; it is called a swallow hole. It is also called ‘Ponor’, and ‘Serbo-Coat.’
  2. Cave in Section – Due to the erosion caused by either running water or surface water, a cavity is formed in the rock which transforms into a cave.
  3. Sink Holes – It is one of the most common features in Karst Topography.  It is a depression on the limestone/dolomitic region that ranges from a shallow saucer shape to a funnel-shaped or cylindrical pipe.
  4. Valley Sinks/Uvalas – It is defined as a complex dosed depression with several lesser depressions
    within its rim.

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Erosional Landforms of Karst Topography

The table below mentions the erosional landforms that characterize karst topography:

Karst Topography – Erosional Landforms

Pools An opening at the top with water collected in the void of the surface with varying depth
Sinkholes Depression on the limestone/dolomitic region. A great variation is seen in sizes of sinkholes with areas from a few sq. m to a hectare and with depth from a less than half a metre to thirty metres or more
Lapies It is formed due to differential solution activity along parallel to sub-parallel joints. They are also called grooved, fluted and ridge-like features in an open limestone field.
Limestone Pavements It is a smoother form of lapies
Caves Cave formation is prominent in areas where there are alternating beds of rocks (shales, sandstones, quartzites) with limestones or dolomites in between or in areas where limestones are dense, massive and occurring as thick beds
Collapse Sinks It is also referred to as ‘Doline.’

(*source – NCERT)

Depositional Landforms of Karst Topography

The table below mentions the depositional landforms that characterize karst topography:

Karst Topography – Erosional Landforms

Stalactites
  • The hanging icicles varying with diameters are called stalactites
  • Usually, the base is broader than the free end of the hanging stalactites
Stalagmites
  • Unlike stalactites those hang from the ceiling; stalagmites rise from the floor
  • It is formed due to the deposition of the dripping water of either the surface water or the stalactites
  • The shapes of stalagmites range from the column, a disc, with either a smooth, rounded bulging end to a miniature crater-like depression
Pillars
  • The combination or fusion of stalactites and stalagmites form the pillars
  • The diameters of pillars vary

What are the suitable conditions for Karst formation?

The karsts are formed in the regions that meet the following conditions:

  1. Karst topography will be found in such regions which will have a large stretch of water-soluble rocks such as limestone at the surface or sub-surface level.
  2. The limestones of the karst topography are not porous.
  3. The rocks found in the karsts are dense, thinly bedded and well jointed.
  4. As the groundwater/surface water is the factor to form the karst topography hence, there should be a perennial source of water and a low water table to allow the formation of conspicuous features.
  5. The solution or moderate to abundant rainfall to cause the solvent action of water i.e. solution of rocks.

How does erosion take place in Karst region?

As the rocks found in the karst regions are thinly bedded and permeable; the surface water drains underground and erodes the rocks with its horizontal and downward movement. The chemical process of solution and precipitation leads to the formation of the landforms either through erosion or deposition.

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Quick Facts about Karsts Regions

  1. The underground drainage system is one of the significant characteristics of the karst regions.
  2. Karst is most strongly developed in dense carbonate rock, such as limestone, that is thinly bedded and highly fractured. (*source – wiki)
  3. 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
    • Poljes
    • Karst valleys

Question Example on Karsts:

Consider the following statements

  1. Karst topography generally forms in areas of abundant rainfall where bedrock comprises of carbonate-rich rock
  2. Some regions of karst topography are dominated by several caves.

Select the correct ones

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2

Answer: C (Abundant rainfall, carbonate-rich rock, caves all are features of karst topography.)

FAQ about Karst Topography

Why is karst topography dangerous?

Karst topography can be a dangerous location to live because the bedrock of the area slowly erodes away. This unstable land can cause huge sinkholes and other geomorphic hazards.

What is needed for karst topography?

The development of all karst landforms requires the presence of rock which is capable of getting dissolved by water(surface and ground water). Although commonly associated with carbonate rocks (dolomite and limestone) other highly soluble rocks such as evaporites (rock salt and gypsum) can also be sculpted into karst terrain.

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