TIBET · ALTIPLANO
DECCAN · COLUMBIA
COLORADO · BUNDEL.
Plateaus
Intermontane, Piedmont & Continental · Volcanic Flood-Basalt vs. Dissected Plateaus · Mineral Storehouses & Indian Peninsular Mosaic (28 Micro-Realms)
Elevated Tablelands, Flood-Basalt Traps & Planetary Mineral Storehouses
Plateaus (Tablelands) are elevated second-order landforms distinguished from mountains by an extensive, relatively flat or undulating summit bounded on one or more sides by steep escarpments. Formed by epeirogenic uplift, crustal thickening, or fissure lava outpourings, they classify by structural position into Intermontane (Tibet, Bolivian Altiplano), Piedmont (Patagonia, Malwa), and Continental Shield Plateaus, and by process into Volcanic Flood-Basalt Traps (Deccan, Columbia) vs. Dissected Plateaus—serving humanity as the primary storehouses of metallic minerals, fertile black Regur soils, and waterfall hydroelectricity.
I. Tableland Morphology, Genesis & Structural Position Types
Tableland Definition
- Elevated upland (>300 m above surroundings)
- Extensive flat-topped summit surface
- Bounded by steep cliffs / escarpments
Mountain vs. Plateau Key
- Defined by summit shape, NOT altitude!
- Tibetan Plateau (4,500 m) is higher than
- Most mountains, yet flat-topped
Epeirogenic & Plume Uplift
- Broad vertical epeirogenic warping
- Or buoyant thermal mantle plume head
- Lifts cratonic block without folding
Collisional Crustal Doubling
- Continent–continent underthrusting
- Doubles SIAL thickness to 70–80 km
- Drives Tibetan & Altiplano uplift
1. Intermontane Plateaus
- Partly or fully enclosed by fold mountains
- World's highest, largest & most complex
- Formed simultaneously with fold belts
Global Intermontane Key
- Tibetan ("Roof of the World" — 2.5M km²)
- Bolivian Altiplano (Andes), Mexican Plateau,
- Tarim Basin, Anatolian (Turkey) & Iranian
2. Piedmont Plateaus
- Situated at the foot of a mountain range
- Bounded on other side by a plain or sea
- Patagonian (Andes), Piedmont (USA), Malwa
II. Continental Shields & Volcanic Flood-Basalt vs. Dissected Plateaus
3. Continental Plateaus
- Rise abruptly from coastal plains or seas
- Far away from fold mountain belts
- Peninsular India, Brazilian, African, Arabian
4. Domed Plateaus (Up-Warped)
- Landmass lifted into a broad rounded arch
- Develops radial drainage outward
- Ozark Plateau (USA) & Chotanagpur domes
Volcanic (Lava) Plateaus
- Quiet fissure eruptions of basic (mafic) lava
- Low-silica fluid basalt spreads as flat sheets
- Buries pre-existing relief under km-thick lava
"Trap" Staircase Relief
- Swedish "Trappa" = Stair / Step
- Successive horizontal basalt lava flows
- Weather into step-like terraced hill slopes!
Global Volcanic Plateaus
- Deccan Traps (Réunion hotspot ~66 Ma)
- Columbia–Snake (USA), Paraná (Brazil),
- Ethiopian, Siberian Traps & Antrim (UK)
Dissected Plateaus
- Tectonically uplifted plateau incised deeply
- By rejuvenated rivers, glaciers or wind
- Colorado Plateau, Allegheny, Bundelkhand
Volcanic vs. Dissected
LAVA BUILD-UP
RIVER INCISION
- Volcanic: Constructional (lava fills valleys flat)
- Dissected: Destructional (rivers cut canyons)
- Old volcanic plateaus become dissected!
III. Dissection Chain, Special Plateaus & Economic Significance
Plateau → Mesa → Butte
- Fluvial & arid dissection fragments tableland
- Into flat-topped Mesas ($W > H$)
- And isolated narrow Buttes ($H > W$)
Loess, Glacial & Karst Plateaus
- Aeolian: Loess Plateau (China) & Potwar (Pak)
- Glacial: Greenland & Antarctic Ice Plateaus
- Karst: Yunnan–Guizhou & Rohtas (Bihar)
Submarine Oceanic Plateaus
- Submerged large igneous provinces (LIPs)
- Ontong Java (Pacific) & Kerguelen (Indian)
- Mascarene Plateau (Seychelles–Mauritius)
"Storehouses of Minerals"
- Denudation strips sedimentary cover off
- Exposes Archaean/Proterozoic metallogenic veins
- #1 economic significance of plateaus!
Global Mining Plateaus
- Katanga / Shaba (DRC-Zambia): Copper & Cobalt
- Kimberley (W. Australia) & Bié: Gold/Diamonds
- Brazilian Highlands (Carajás): High-grade Iron
Lateritic Bauxite Duricrusts
- Flat plateau tops retain monsoon water
- Deep desilication leaches silica downward
- Concentrates Bauxite caps (Odisha/Jharkhand)
Black Regur Soil (Vertisols)
- In-situ weathering of Deccan & Malwa basalt
- High moisture retention (montmorillonite clay)
- Prime belt for Cotton, Sugarcane & Citrus
Waterfall Hydroelectricity
- Rivers plunge off steep plateau escarpments
- Ideal hydraulic head for turbines
- Jog (Sharavathi), Shivasamudram, Hundru
IV. Climate Role & The Indian Peninsular Plateau Mosaic (NCERT India Ch 2)
Tibetan Thermal Monsoon Pump
- Tibet acts as an elevated mid-tropospheric heat source
- Drives Tropical Easterly Jet (TEJ)
- And semi-arid plateaus host Merino/Pashmina grazing
Central Highlands (India)
- North of Narmada river, sloping NE (Chambal/Betwa)
- Malwa: Volcanic basalt + Chambal badland gullies
- Bundelkhand: Dissected senile granite-gneiss
Chotanagpur & "Pat" Lands
- "Ruhr of India": Damodar coal graben + Singhbhum Fe/Cu
- Multi-level polycyclic peneplain
- Capped by flat laterite-basalt mesas ("Pat" lands)
Deccan Plateau Sub-Units
- Maharashtra: Step-like Deccan Trap lava beds
- Karnataka: Hilly forested Malnad + rolling Maidan
- Telangana/Rayalaseema: Archaean gneissic tors
Meghalaya & Malda Fault Gap
- Garo, Khasi, Jaintia & Mikir (Karbi-Anglong)
- Geologically part of Peninsular Plateau (NOT Himalaya!)
- Detached by down-faulting of Malda Gap
Master Plateaus Matrix
- Synthesizes all Plateau classes & resources
- Links World L Mountains (59) to Plateaus (60)
- Transitions to Realm 61 (Plains)
Core Distinctions
• Intermontane Plateaus: Enclosed between fold mountain ranges; highest and most extensive in the world (Tibetan Plateau between Kunlun and Himalayas; Bolivian Altiplano in the Andes; Anatolian, Iranian, Mexican).
• Piedmont Plateaus: Bordered by mountains on one side and a plain or ocean on the other (Patagonian Plateau, Piedmont Plateau USA, Malwa Plateau between Aravalli and Vindhya).
• Continental Plateaus: Rise abruptly from coastal plains or seas away from fold mountains (Deccan/Peninsular India, Brazilian, African, Arabian, Western Australian).
• Volcanic Plateaus: Constructional tablelands built by quiet fissure eruptions of fluid basaltic lava that bury pre-existing relief into step-like Traps (Deccan, Columbia-Snake, Ethiopian, Antrim).
• Dissected Plateaus: Uplifted plateaus deeply incised by rejuvenated rivers into gorges, canyons, mesas, and buttes (Colorado Plateau, Bundelkhand).
The Meghalaya (Garo, Khasi, Jaintia) and Karbi-Anglong Plateau is NOT part of the Northeastern Himalayas—it is a detached northeastern extension of the ancient Peninsular Chotanagpur Plateau, separated by the down-faulted Malda (Garo–Rajmahal) Gap filled by Ganga-Brahmaputra alluvium.
Global Plateaus Matrix
Type, Exemplar & Economic Value Key