Plateau Formation

Definition of a Plateau

A plateau is an elevated flat-topped landform that rises sharply above the surrounding area on at least one side. It is often called a tableland due to its extensive flat surface.

Key Features of Plateaus

• Broad and flat or gently undulating surface
• Bounded by steep slopes or escarpments
• Higher than surrounding plains or valleys
• Formed by endogenic (internal) and exogenic (external) forces
• Found on all continents

Importance of Plateaus

• Storehouse of mineral wealth (e.g., Chota Nagpur Plateau)
• Sites for hydroelectric projects due to deep river valleys
• Fertile soils in some volcanic plateaus (e.g., Deccan)
• Important cultural and ecological regions
• Climatic significance: act as barriers influencing wind and rainfall

Types of Plateaux

a) Dissected Plateaus

• i. Formation Process: Uplifted land is eroded by rivers over time, creating a rugged surface
• ii. Features: Irregular topography, deep valleys, hills
• iii. Examples: Colorado Plateau (USA), Deccan Plateau (India)
• iv. Colorado Plateau: Known for the Grand Canyon carved by the Colorado River
• v. Tibetan Plateau: Though intermontane, parts are dissected in the east

b) Volcanic Plateaus

• i. Formation: Formed from successive lava flows from fissure eruptions
• ii. Lava Flows: Create thick basalt layers (also called traps)
• iii. Examples: Deccan Traps (India), Columbia Plateau (USA)
• iv. Deccan Traps: One of the largest volcanic features on Earth
• v. Columbia Plateau: Formed by flood basalts in western USA

c) Intermontane Plateaus

• i. Definition: Plateaus surrounded by mountain ranges
• ii. Features: High elevation, enclosed, tectonic in origin
• iii. Example: Tibetan Plateau – world’s highest and largest plateau
• iv. Tibetan Plateau: Formed by the collision of Indian and Eurasian plates

d) Continental Plateaus

• i. Definition: Plateaus located on the interior of continents
• ii. Characteristics: Broad, extensive, may be residual or tectonic
• iii. Examples: Australian Plateau, African Plateau

Economic Significance of Plateaus

• Minerals: Coal, iron, manganese, copper, etc.
• Agriculture: Fertile soils in volcanic plateaus
• Forestry and Grazing: Extensive woodlands and grasslands
• Tourism: Natural beauty and unique geography
• Hydropower: Steep slopes ideal for dams and reservoirs

Formation of Plateaus

A) Tectonic Plateaus

Formed by internal earth movements (endogenetic forces)

• i. Crustal Shortening: Compression of tectonic plates causes uplift (e.g., Tibetan Plateau)
• ii. Thermal Expansion: Heated mantle causes uplift of crust (e.g., East African Rift system)

B) Volcanic Flood Basalts (Traps)

Plateaus formed by repeated lava flows from volcanic fissures

• i. Examples:
  • Deccan Traps (India) – ~65 million years old
  • Siberian Traps (Russia) – linked to mass extinctions

C) Other Formation Processes

• i. Uplift and Erosion: Old mountains eroded into flat surfaces and later uplifted
• ii. Example: East African Highlands – uplifted due to tectonic rifting and erosion