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Plateaus — Types and Global Distribution
3.1 Definition and Classification
A plateau is an elevated, relatively flat-topped landform with steep sides, distinct from surrounding lowlands. They cover approximately 45% of Earth's total land area — the most extensive landform type.
Formation mechanisms:
- Tectonic uplift — large blocks of land uplifted by tectonic forces
- Lava outpouring — successive basaltic lava flows building flat surfaces
- Erosion — high terrain reduced to flat plateau surface (planation surface)
3.2 Types of Plateaus
1. Intermontane Plateaus
Surrounded or enclosed by mountain ranges — the most rugged type.
| Plateau | Location | Average Elevation | Key Fact |
|---|---|---|---|
| Tibetan Plateau | China-Nepal | 4,500 m | World's highest; "Roof of World"; "Third Pole"; 2.5 million km² |
| Bolivian Plateau (Altiplano) | Bolivia-Peru | 3,800 m | Enclosed by two Andes ranges; Lake Titicaca (3,812 m — world's highest navigable lake) |
| Iranian Plateau | Iran, Afghanistan | 900–1,500 m | Includes deserts; Zagros and Elburz Mts. on sides |
| Mexican Plateau | Mexico | 1,100–2,500 m | Between Sierra Madre Occidental and Oriental |
2. Continental Plateaus / Lava Plateaus
Formed by extensive lava outpourings or tectonic uplift of broad areas.
| Plateau | Location | Key Fact |
|---|---|---|
| Deccan Plateau | Peninsular India | ~6.5 lakh km²; avg 600 m; basaltic; source of major Indian rivers |
| Columbia Plateau | USA (Oregon, Washington, Idaho) | ~400,000 km²; Columbia River flows through it |
| Brazilian Plateau (Planalto) | Brazil | ~5 million km²; world's largest continuous plateau area |
| African Shield Plateaus | Africa | Congo Basin surrounded by plateaus; East African Plateau (1,200–1,500 m) |
| Antrim Plateau | Northern Ireland | Basaltic lava plateau; Giant's Causeway (UNESCO World Heritage) |
3. Piedmont Plateaus
Located at the foot of mountains, separated from lowlands by steep scarps.
| Plateau | Location | Key Fact |
|---|---|---|
| Appalachian Plateau | Eastern USA | West of Appalachian Mountains; coal-bearing Carboniferous rocks |
| Malwa Plateau | Central India (MP, Rajasthan) | Avg 500 m; drained by Chambal, Betwa, Kali Sindh |
| Patagonian Plateau | Argentina | Cold desert plateau east of Andes; world's largest cold desert |
| Piedmont Plateau | Eastern USA (Carolinas, Virginia) | Between Appalachians and Atlantic Coastal Plain |
3.3 Tibetan Plateau — Detailed Study (Most Important Plateau for RPSC)
The Tibetan Plateau (4,500 m average elevation, ~2.5 million km²) is the geographic centrepiece of Asia.
Physical Geography
- Flanked by Himalayas (south), Karakoram (northwest), Kunlun (north), Hengduan (east)
- Contains Nam Tso (4,718 m — Tibet's largest lake) and Qinghai Lake (China's largest freshwater lake)
- Glaciers: 37,000+ glaciers; stores ~37% of world's freshwater in ice — hence "Third Pole"
River Sources
The plateau is the origin of eight major rivers: Yangtze, Yellow River (Huang He), Mekong, Salween, Irrawaddy, Brahmaputra (Tsangpo), Indus, and Sutlej — making it the "Water Tower of Asia."
Climate Impact
The plateau's altitude creates intense heating in summer, driving the Asian Monsoon system through a thermodynamic pressure differential. Loss of Tibetan glaciers threatens downstream water security for 1.5+ billion people.