Plateaus are elevated, flat-topped landforms that rise sharply above the surrounding terrain on at least one side, covering roughly 45 percent of the Earth's land surface. Often referred to as 'tablelands', they are shaped by endogenic forces such as tectonic uplift, volcanism, and crustal warping, as well as exogenic forces like denudation, glacial scouring, and fluvial dissection. Their genesis is fundamentally tied to dynamic mantle plume activities, orogenic compression, and continental rifting. From a climatic and economic perspective, plateaus act as formidable barriers to atmospheric circulation, creating rain-shadow deserts on their leeward sides while housing rich mineral wealth due to ancient cratonic roots and exposed shield rocks. Understanding their types—intermontane, continental, piedmont, and dissected—along with spatial patterns like the Tibetan Plateau and the Deccan Trap, is critical for candidates preparing for UP TGT/PGT Geography and UGC-NET examinations.
1. Morphogenetic Classification & Types of Plateaus
Classification of plateaus based on their mode of origin, tectonic environment, and topographic evolution.
- Intermontane Plateaus: Highest and most extensive, enclosed by fold mountains (e.g., Tibetan Plateau, Bolivian Plateau).
- Continental Plateaus: Formed by extensive continental uplift or massive basaltic lava flows, bordered by plains or oceans (e.g., Deccan Plateau, Canadian Shield).
- Piedmont Plateaus: Located at the base of high mountain ranges, bounded by plains on one side (e.g., Malwa Plateau, Piedmont Plateau of USA).
- Dissected Plateaus: Formed by vertical fluvial erosion and uplift of ancient tablelands, creating rugged relief (e.g., Chota Nagpur Plateau, Scottish Highlands).
- Volcanic Plateaus: Built by fissure eruptions of fluid basic lava accumulating in thick horizontal layers (e.g., Columbia Plateau, Antrim Plateau).
- Tibetan Plateau is the highest and largest intermontane plateau globally.
- Deccan Plateau represents a classic flood basalt province associated with the Réunion hotspot.
- Dissected plateaus exhibit youthful-to-mature river valleys cutting through ancient horizontal strata.
2. Endogenic & Exogenic Formative Mechanisms
Geomorphic processes responsible for the creation, evolution, and destruction of plateau topography.
- Epeirogenic Movements: Broad vertical uplift of continental crust without significant folding or faulting.
- Orogenic Compression: Crustal shortening and tectonic thickening leading to high-altitude intermontane basins and plateaus.
- Fissure Volcanism: Upwelling of low-viscosity basaltic magma through deep crustal fractures, forming horizontal trappean topography.
- Fluvial Dissection: Downcutting by rivers transforming smooth tablelands into deeply incised plateau-and-valley systems.
- Glacial Scouring: Plucking and abrasion by continental ice sheets smoothing high-latitude shield surfaces (e.g., Laurentian Plateau).
- Plateaus act as geological archives preserving ancient cratonic roots and shield structures.
- Exogenic denudation continuously reduces plateau surface areas, eventually converting them into peneplains.
3. Major Global Plateaus & Tectonic Settings
Spatial distribution of world plateaus in relation to lithospheric plates and global climatic belts.
- Tibetan Plateau: Formed by the collision of the Indian and Eurasian tectonic plates (Cenozoic Orogeny).
- Colorado Plateau: Broad epeirogenic uplift cut by the entrenched meanders of the Colorado River, showcasing horizontal sedimentary strata.
- Patagonian Plateau: Classic rain-shadow desert plateau east of the Andes Mountains, shaped by arid denudation.
- Anatolian Plateau: Intermontane plateau nestled between the Pontic and Taurus mountain ranges in Turkey.
- Azn/African Shield Plateaus: Ancient Precambrian platforms rich in metallic minerals and surrounded by narrow coastal plains.
- Most high plateaus coincide with active or inactive convergent plate boundaries.
- Rain-shadow effect is the dominant climatic control on arid plateaus like Patagonia and Colorado.
Spatial Patterns & Regional Distribution
🌐 Global Geographic Belts & Spatial Variation
Global plateaus are primarily concentrated in two structural belts: the Alpine-Himalayan belt (featuring the Tibetan, Anatolian, and Iranian plateaus formed by plate convergence) and the stable Precambrian cratonic shields (such as the Laurentian, Brazilian, and African plateaus formed by long-term epeirogenesis and denudation). Volcanic plateaus cluster around major mantle hotspots and continental flood basalt provinces like the Deccan, Columbia, and Siberian Traps.
🇮🇳 Indian Subcontinent Context & Regional Corridors
In India, plateaus dominate the peninsular shield region. The Deccan Plateau spans Maharashtra, Karnataka, and Andhra Pradesh, formed by Cretaceous-Eocene basaltic volcanism. The Chota Nagpur Plateau in Jharkhand and Chhattisgarh is rich in metallic minerals (iron, coal, mica) and dissected by the Damodar River. The Malwa Plateau lies between the Aravalli and Vindhyan ranges, while the Shillong Plateau represents an outlying detached fragment of the Indian Peninsula separated from the Rajmahal Hills by the Malda Gap.
Mnemonics, Memory Shortcuts & Exam Traps
I = Intermontane (Tibetan), V = Volcanic/Lava (Deccan), C = Continental (Shields), P = Piedmont (Malwa/Piedmont).
C = Chota Nagpur (Ruhr of India, Coal/Iron), C = Chhattisgarh (Bauxite/Iron), M = Malwa (Agricultural, Black soil).