Meaning of Karst Topography

Karst topography is a landscape formed by the dissolution of soluble rocks such as:

• Limestone
• Dolomite
• Gypsum

It is characterised by:

• Underground drainage systems
• Sinkholes
• Caves and caverns

The dissolution occurs when rainwater mixed with carbon dioxide forms carbonic acid, which dissolves limestone.

Rocks Associated with Karst

Limestone

• Sedimentary rock is mainly composed of Calcium Carbonate (CaCO₃).
• Formed from corals, shells, and marine organisms.

Chalk

• Soft and pure form of limestone.
• Highly porous, hence karst is less developed.

Conditions for Karst Formation

Karst landscapes develop best when:

• Limestone rocks are dense and fractured
• Rainfall is moderate to heavy
• Water table is low
• Rocks contain many joints and fissures

These conditions allow groundwater circulation and chemical dissolution.

Distribution of Karst

World Examples

• Causses (France)
• Kwangsi (China)
• Yucatán Peninsula (Mexico)
• Kentucky and Florida (USA)

Karst Regions in India

• Vindhya region
• Dehradun and Eastern Himalayas
• Pachmarhi (Madhya Pradesh)
• Borra Caves (Andhra Pradesh)
• Bastar (Chhattisgarh)
• Gupt Godavari caves (Uttar Pradesh)

Characteristics of Karst Topography

1. Absence of surface drainage
2. Development of underground drainage systems
3. Presence of sinkholes and caves
4. Formation of limestone pavements
5. Presence of dry valleys

Erosional Landforms of Karst

1. Limestone Pavement

• Flat limestone surface with cracks.
• Consists of:

Clints → Limestone blocks
Grikes → Deep cracks between blocks.

2. Sinkholes / Swallow Holes / Dolines

• Circular depressions formed by the dissolution or collapse of limestone.

Local names:

• Cenotes – Mexico
• Blue holes – Underwater sinkholes
• Sotanos – Mexico

3. Blind Valley

• A valley that ends abruptly where a stream disappears underground.

4. Lapies / Karren

• Small grooves, ridges, and pits formed by the solution of limestone.

5. Pinnacles

• Sharp vertical limestone projections formed due to dissolution.

6. Karst Window (Fenster)

• Occurs when the roof of an underground cave collapses, exposing the underground stream.

7. Uvala

• A large depression formed by the merging of several sinkholes (dolines).

8. Polje

• Large flat-floored depression in karst areas.
• Size: 5–400 km².

9. Caves and Caverns

• Underground cavities formed by the dissolution of limestone by groundwater.

Example:

• Borra Caves (Andhra Pradesh)

Depositional Landforms of Karst

Deposits inside caves are collectively called Speleothems.

1. Stalactites

• Icicle-shaped deposits hanging from cave roofs.
• Formed by the precipitation of calcium carbonate.

2. Stalagmites

• Upward-growing deposits on cave floors.
• Formed from dripping water containing minerals.

3. Pillars (Columns)

• Formed when stalactites and stalagmites join together.

4. Drapes / Curtains

• Thin sheet-like calcite deposits hanging from cave ceilings.

5. Tufa

• A porous limestone deposit formed by precipitation of calcium carbonate from water.

6. Travertine

• A harder and more compact form of tufa formed near springs and rivers.

Karst Lakes

• Formed due to the collapse of underground caves.
• Often, temporary lakes appear after heavy rainfall.

Soil in Karst Regions

Terra Rossa

• Reddish clayey soil formed over limestone.
• Well-drained and rich in iron oxide.

Economic Importance of Karst

1. Limestone mining
2. Cement industry
3. Building material
4. Tourism (caves)

However:

• Agriculture is limited due to thin soil cover and poor drainage.