karst topography geography upsc

Questions:

Q1. Discuss critically, Development of Karst landforms. ( UPPSC 2005)

Q2. Analyze systematically the development of landforms in the Karst region. ( UPPSC 1994)

Q3. Discuss the conditions required for the development of Karst topography with associated features. ( 63rd BPSC, 2019)

Q4. Explain the evolution of valley sinks or uvulas. (NCERT)

Q5.  The underground flow of water is more common than surface run-off in limestone areas. Why? (NCERT)

Answer. 

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Surface water not only forms landforms, but groundwater also forms many types of landforms. We do not get to see the landforms made by groundwater everywhere, we get to see them in those places where the land is made of limestone or dolomite rock.

In any limestone or dolomite area, the topography formed by the process of dissolution by groundwater and their deposition is called karst topography.

Prerequisites for the development of karst topography:

The following conditions are necessary for the development of karst topography-

• Rocks are eroded by the movement of groundwater both vertically and horizontally. Physical or mechanical erosion of rocks occurs in all regions but it is not sufficient to develop any visible landforms. Therefore, where there is a sufficient amount of carbonate rocks such as limestone and dolomite or soluble rocks such as gypsum and salt rocks as well as a humid climate, there is the development of groundwater erosion or deposition topography, the topography developed in these areas is called karst topography.
• Karst topography is formed by erosion and slurry deposition of carbonate rocks (limestone or dolomite) and water-soluble rocks (gypsum and salt rocks) by underground water.
• The region must have a thick deposit of carbonate rocks or soluble rocks for the development of karst topography.
• The area must have sufficient rainfall or groundwater to dissolve carbonate rocks or water-soluble rocks.

Karst Topography

Erosional landforms of Karst Topography

The following are erosional Karst topography :

• Sinkhole
• Collapse sink
• Uvalas
• Caves

Sinkhole:

• Sinkhole topography is a very common erosional topography of the karst region.
• In the karst zone, swallow holes are first formed which are small to medium-sized round holes or shallow pits.
• Swallow holes are formed through the dissolution process.
• Over time, the swallow holes turn circular at the top and funnel-shaped at the bottom, called sinkholes, from where water seeps into the ground.

Collapse sink;

• The topography formed after merging and collapsing of two or more sinkholes is called collapse sinkholes.

Uvalas:

• When two or more sinkholes join after the collapse of their roof and form long, narrow wide trenches that are like a valley, which is called valley sinks or Uvalas.

Cave:

• Caves are formed in areas where limestone or dolomite rocks are present in between two other hard rocks (quartzite, sandstone). And later, caves are formed after the dissolution and erosion of limestone rocks.
• Usually, the caves are open on one side from which the stream of water comes out.
• Caves that are open from two sides are called tunnels.

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Depositional landforms

Karst deposition landforms are often formed within the cave itself. As we know that the chemical composition of limestone is calcium carbonate which easily dissolves in carbonated water (carbonated water or dissolved carbon in rainwater). This is the deposition of calcium carbonate (and the water evaporates and the carbon dioxide is released) and creates a variety of landforms in the cave

Three types of landforms are created:

• Stalactites
• Stalagmite
• Pillars

Stalactites: 

These stalactites are hanging pillars of various thicknesses that hang on the ceiling of caves. It is formed by the dripping of a mixed solution chosen from the ceiling.

Stalagmite: 

Stalagmite is formed by the deposition of calcium carbonate which rises up from the cave floor. It is also made from a mixed solution.

Pillar: 

When stalagmite accumulates from the floor of the cave to the ceiling. Such deposits are called pillar landforms.

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• UPPSC Geomorphology: (भू- आकारिकी) PYQ Solutions
• कार्स्ट स्थलाकृति भूगोल

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