Karst Landforms and the Cycle of Erosion
Geography › Rocks, Erosion and Landforms · Topic 5.6
Karst topography is the landscape of limestone and other soluble rocks shaped by the solution of rock by slightly acidic water, producing sinkholes, caves, stalactites and stalagmites and underground drainage. The cycle of erosion, proposed by William Morris Davis, describes how a landscape passes through youth, maturity and old age to a nearly level peneplain.
5 min read · UPSC Prelims · Geography · Rocks, Erosion and Landforms
At a Glance
- Rock Limestone, dolomite, gypsum
- Process Solution by carbonic acid
- Surface forms Sinkholes, uvalas, poljes, lapies
- Underground forms Caves, stalactites, stalagmites, pillars
- Cycle of erosion Youth, maturity, old age (Davis)
- Exam link UPSC Prelims, Geography: Rocks, Erosion and Landforms
Where Does It Fit?
This is the sixth topic of the category on rocks, erosion and landforms. The previous topic described river landforms, and this one covers limestone landscapes and a theory of landscape change. The next topic covers marine landforms and coastlines. Previous topic: Fluvial Landforms and Drainage Patterns. Next topic: Marine Landforms and Coastlines.
What Is Karst Topography?
In short: karst is a landscape where soluble rock has been dissolved by water into sinkholes, caves and underground streams.
The term karst comes from the Kras plateau in Slovenia and Italy. Karst landscapes develop in regions of thick, well-jointed limestone, dolomite or gypsum, with enough rain. Rainwater absorbs carbon dioxide from the air and soil and becomes weak carbonic acid, which dissolves calcium carbonate, a process called carbonation, as described in Exogenic Movements, Denudation and Weathering. The water enlarges joints and bedding planes, and most drainage goes underground, so there are few surface streams. The characteristic features are a pitted surface and a network of caves below. The rock itself is explained in Sedimentary Rocks.
What Are the Surface Karst Landforms?
| Landform | Description |
|---|---|
| Karren or lapies | Small grooves and ridges cut in bare limestone by dissolving rainwater; a surface of ridges and furrows is called a limestone pavement |
| Sinkhole (doline) | A funnel-shaped depression from a few metres to hundreds of metres across, formed by solution or by the collapse of a cave roof |
| Swallow hole | A sinkhole where a stream disappears underground |
| Uvala | A large basin made by the merging of several sinkholes |
| Polje | A very large flat-floored depression, kilometres in size, in karst |
| Karst window and natural bridge | Collapse exposes an underground stream, and a surviving arch forms a natural bridge |
| Tower karst | Isolated steep limestone hills in humid tropical karst, as in Guilin in China |
What Are the Underground Features: Caves, Stalactites and Stalagmites?
Underground water dissolves the rock along joints and creates passages and chambers, which form caves. When water rich in dissolved calcium carbonate drips from the cave roof, part of the carbon dioxide escapes and calcite is deposited. Three kinds of cave deposits, called speleothems, result:
- Stalactites: icicle-like formations hanging from the roof of the cave.
- Stalagmites: columns growing upward from the floor, formed by drips from above.
- Pillars or columns: a stalactite and stalagmite that meet and join.
The longest cave system in the world is the Mammoth Cave system in Kentucky, USA, which has over 650 km of surveyed passages. India’s well-known limestone caves include the Borra Caves in the Araku Valley of Andhra Pradesh, Belum Caves in Kurnool, one of the longest caves in the plains of peninsular India, Mawsmai and Krem Liat Prah in Meghalaya, Gupt Godavari in Chitrakoot, and the Sahastradhara and Robber’s Cave near Dehradun. The Meghalaya caves are among the longest in the subcontinent. Karst is also important for water: the aquifers of limestone are a major source of groundwater, though they are vulnerable to pollution, since water moves rapidly through channels without filtration.
What Is the Cycle of Erosion?
The American geographer William Morris Davis proposed the geographical cycle, also called the cycle of erosion, in 1899. He suggested that a land uplifted rapidly is then worn down by rivers through a regular sequence of stages, if there is no further uplift, as structure, process and time determine the landscape.
| Stage | Features |
|---|---|
| Youth | Upland with steep, V-shaped valleys, rapids, waterfalls, and broad flat interfluves; vertical erosion |
| Maturity | Maximum relief; well-developed streams, gentle valley floors and meanders; rounded hills |
| Old age | Very gentle slopes, wide floodplains and meanders; the land is reduced to a nearly flat surface, the peneplain, with occasional resistant hills called monadnocks |
Davis described a cycle that could be interrupted by renewed uplift, called rejuvenation, which produces features such as river terraces and incised meanders. Later geomorphologists criticised the theory. Walther Penck in the 1920s argued that uplift and erosion occur at the same time, and that slopes retreat parallel to themselves, and L. C. King’s pediplanation theory, based on arid and semi-arid landscapes of Africa, stressed parallel retreat of slopes leading to extensive plains called pediplains. As an analytical point, Davis’s model is now seen as an idealised teaching framework, but its vocabulary of youth, maturity and old age remains useful for describing landscapes.
Why Is This Topic Important?
- Karst Frequent Prelims theme
- Indian caves Map-based facts
- Theory Davis, Penck and King
What Came Next?
The next topic describes marine landforms and coastlines. Next topic: Marine Landforms and Coastlines.
Key People and Terms
- Karst Landscape on soluble rock
- Sinkhole Funnel-shaped depression
- Speleothem Cave mineral deposit
- Peneplain Almost flat old-age surface
- Monadnock Resistant hill on a peneplain
- Rejuvenation Renewed erosion after uplift
Exam Corner
Points to Remember
- Karst forms on limestone by solution.
- Stalactites hang; stalagmites rise.
- Davis proposed the cycle in 1899.
- End stage of the cycle is a peneplain.
- Borra and Belum are caves in Andhra Pradesh.
Do Not Confuse With
- Stalactite and stalagmite Hanging versus rising
- Peneplain and pediplain Davis versus King
- Sinkhole and polje Small versus very large depression
Memory Hook
Tites hang tight from the ceiling, mites rise from the floor; youth cuts, maturity bends, old age planes.
Mains Angle
Questions ask for karst features and theories of erosion. These points add depth.
- Process Carbonation of limestone
- Water Aquifers and pollution risk
- Theory Davis versus Penck
A Question You May Face
An original practice question, not a past paper question.
“Describe the characteristic landforms of karst regions and give examples from India.”
How to Answer
- Process Solution of limestone.
- Surface Sinkholes and poljes.
- Underground Caves and speleothems.
- India Borra and Belum caves.
GS Relevance
Frequently Asked Questions
What is karst topography?
Karst topography is the landscape formed in regions of soluble rock, mainly limestone, by the dissolving action of slightly acidic water. It has sinkholes, caves, underground streams and few surface streams, and is named after the Kras plateau of Slovenia.
What is the difference between stalactites and stalagmites?
Stalactites are icicle-shaped deposits of calcite that hang from the roof of a cave, formed by dripping water. Stalagmites are columns that grow upward from the floor beneath the drips. When they meet, they form a pillar or column.
What is a sinkhole?
A sinkhole or doline is a funnel-shaped or circular depression in karst land, formed by the solution of limestone at the surface or by the collapse of the roof of an underground cave. Several sinkholes may merge into a larger basin called an uvala.
What is Davis's cycle of erosion?
The cycle of erosion proposed by William Morris Davis in 1899 describes the evolution of a landscape after uplift through youth, maturity and old age. The end stage is a nearly flat peneplain with occasional resistant hills called monadnocks.
Where are the famous limestone caves of India?
Famous limestone caves of India include the Borra Caves in the Araku Valley, Andhra Pradesh, the Belum Caves in Kurnool, Mawsmai and Krem Liat Prah in Meghalaya, Gupt Godavari in Chitrakoot, and the Sahastradhara and Robber's Cave near Dehradun.
PYQ Practice — Statement Analysis
1 Stalactites grow upward from the floor of a cave.
Stalactites hang from the roof; stalagmites rise from the floor.
2 Karst topography is characteristic of limestone regions.
The rock is dissolved by weak acid.
3 The cycle of erosion was proposed by W. M. Davis.
He proposed it in 1899.
4 A peneplain is the youthful stage of the cycle of erosion.
It is the end stage of old age.
Related Topics
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