Mountains and plateaus of the world

Detail

1. How mountains form: fold mountains at convergent plate boundaries

• Plate tectonics (the idea that the Earth's outer shell is broken into large moving slabs called plates) explains where most mountains stand.
• Convergent boundary (a place where two plates move towards each other):
• Two plates push into each other.
• The rock layers between them bend into folds and break along faults.

• The crust thickens and rises, and fold mountains form.

• Young fold mountains are tall, have sharp peaks and are still rising. Erosion has not yet worn them down.

• Himalaya, a live example:
• The Indian Plate hit the Eurasian Plate about 50 million years ago. The two plates have kept pushing together slowly ever since, raising the Himalaya and the Tibetan Plateau to their present heights [4].
• The two plates still close in at about 40–50 mm a year. India is pushed northward under Eurasia, and this causes many earthquakes in the Himalayan belt [3].
• This is why the Himalaya is still rising and why the whole belt is a high earthquake zone.

2. The two belts of young fold mountains

Belt	Ranges (roughly west → east, or north → south)	Plate setting
Alpine-Himalayan belt	Atlas → Pyrenees → Alps → Apennines → Dinaric Alps → Carpathians → Caucasus → Taurus → Zagros → Elburz → Hindu Kush → Karakoram → Himalaya	African, Arabian and Indian plates pushing north into Eurasia (land plate meeting land plate)
Circum-Pacific belt ("Ring of Fire" mountains)	Rockies (Canada–USA); Andes (South America)	Ocean plates sliding under land plates around the Pacific

Where each range of the Alpine-Himalayan belt lies:

• Atlas: north-west Africa (Morocco, Algeria, Tunisia). Highest peak Toubkal (about 4,167 m, Morocco).
• Pyrenees: on the France–Spain border, with Andorra between them.
• Alps: an arc across France, Switzerland, Italy, Germany and Austria. Highest peak Mont Blanc (about 4,808 m, France–Italy).
• Apennines: the "backbone" running down the length of Italy.
• Dinaric Alps: along the Adriatic coast of the Balkans.
• Carpathians: an arc through Slovakia, Poland, Ukraine and Romania.
• Caucasus: between the Black Sea and the Caspian Sea (see below).
• Taurus: southern Turkey, along the Mediterranean.
• Zagros: western Iran, along the Iraq border. These are folded rocks with oil traps.
• Elburz (Alborz): northern Iran, just south of the Caspian. Highest peak Damavand (about 5,610 m), a volcano.
• Hindu Kush, Karakoram, Himalaya: they meet at the Pamir Knot (see Section 4).

3. Key young fold ranges in detail

Andes, the world's longest continental range

• Length and location: about 7,000 km down the western edge of South America.
• Seven countries (north → south): Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, Argentina.
• How the Andes formed (subduction):
• Subduction means one plate sinks under another. The heavier ocean plate goes down because it is denser.
• The Nazca Plate (an ocean plate under the Pacific) slides under the South American Plate.
• The edge of the land plate is squeezed and folded upward, which builds the Andes.

• The sinking plate melts deep below. The molten rock (magma) rises and forms a chain of volcanoes along the range.

• Altiplano ("high plain"): a high flat basin between two Andean ridges, mainly in Bolivia and Peru. It holds Lake Titicaca on the Peru–Bolivia border.

• Aconcagua (about 6,961 m, Argentina): the highest peak of the Andes and of the Americas, and the highest in the world outside Asia.
• Climate link: the Andes block winds. This helps keep the Atacama Desert (Chile) on the west very dry and creates the dry Patagonia on the east, in the rain shadow (the dry side of a mountain, away from the moist wind).

Caucasus Mountains

• Location: between the Black Sea (west) and the Caspian Sea (east), across Russia, Georgia, Armenia and Azerbaijan.
• The crest of the Greater Caucasus is often taken as part of the Europe–Asia boundary.
• Elbrus (about 5,642 m, Russian side) is a dormant volcano (one that has not erupted in recorded time but may erupt again). It is usually counted as Europe's highest peak, higher than Mont Blanc.
• Trap: Mont Blanc is the highest peak of the Alps. It is Europe's highest only if the Caucasus is counted as part of Asia.

Rockies

• They run from western Canada through the western USA. They form the western edge of the Great Plains and the continental divide (the ridge that decides whether rivers flow to the Pacific or to the Atlantic and Arctic).

4. Other types of mountains

Type	How it forms	World examples	Indian example
Old fold mountains	Folded hundreds of millions of years ago. Long erosion has left them low and rounded	Appalachians (eastern USA), Urals (Russia; the classic Europe–Asia divide near 60°E; rich in minerals), Scandinavian highlands (Norway–Sweden), Great Dividing Range (eastern Australia), Drakensberg (South Africa–Lesotho; the raised edge of the South African plateau)	Aravallis, among the oldest fold mountains in the world
Block mountains	Faults (cracks) break the crust into blocks. Raised blocks are called horsts and sunken blocks are called grabens	Vosges (France) and Black Forest (Germany), two horsts on either side of the Rhine rift valley (a graben); Sierra Nevada (California, USA)	Satpura is often cited
Volcanic mountains	Lava and ash pile up around a vent	Kilimanjaro (Tanzania, about 5,895 m, Africa's highest; snow-capped though near the equator at about 3°S), Fuji (Honshu, Japan, about 3,776 m), Etna (Sicily, Italy; one of Europe's most active volcanoes)	Barren Island (Andaman Sea), India's only active volcano

5. Pamir Knot and Hindu Kush: the mountain hub of Asia

Pamir Knot ("Roof of the World")

• A mountain knot is a point where several great ranges meet like strings tied together.
• Local name Bam-i-Dunya, Persian for "Roof of the World".
• Location: mainly in Tajikistan (Gorno-Badakhshan), with Afghanistan's Wakhan Corridor (a narrow strip of land) on the south. It reaches the edges of China and Kyrgyzstan.
• Ranges that radiate from it:
• Hindu Kush: south-west, into Afghanistan.
• Karakoram: south-east. The Himalaya joins the knot through the Karakoram.
• Kunlun: east, along the northern edge of Tibet.

• Tian Shan: north-east, into Kyrgyzstan and Xinjiang.

• Wakhan Corridor, India link: the corridor touches Gilgit-Baltistan. India counts Gilgit-Baltistan as part of its Union Territory of Ladakh, though Pakistan occupies it. On that basis India claims a land border with Afghanistan.

Hindu Kush

• Extent: about 800 km through central Afghanistan into northern Pakistan, west of the Pamirs.
• Highest peak: Tirich Mir (about 7,700 m, Chitral district, Pakistan).
• Passes and routes:
• Salang Pass (north of Kabul) crosses the main range. It links Kabul with northern Afghanistan and Central Asia.
• Khyber Pass lies just south, in the Spin Ghar (Safed Koh) range. It links Peshawar (Pakistan) with Kabul.

• Together these formed the old Central Asia → Afghanistan → Indian plains route.

• Why these passes mattered:

• Armies came this way: Alexander, the Ghaznavids, Ghurids, Mughals (Babur) and others.
• Trade and ideas came too, including caravans, Buddhism (Gandhara) and Silk Road links.

• Today the region is central to India–Afghanistan–Central Asia connectivity debates. Since Pakistan blocks direct land transit, India uses routes like Chabahar (Iran).

• Hazard: the Hindu Kush–Pamir zone has frequent deep earthquakes because the plates there are still pushing together.

6. Plateaus

• Plateau: land that rises above the surrounding area, with a flat top and steep sides.
• NCERT calls plateaus "storehouses of minerals", because many are made of old, hard rocks that are rich in ores.

Main types of plateau:

Type	Meaning	Examples
Intermontane	Surrounded by mountains	Tibetan, Bolivian Altiplano, Mongolian, Anatolian, Iranian
Piedmont	At the foot of mountains, on one side	Patagonia; Malwa (India)
Continental / shield	Large, old, stable blocks	Arabian, Brazilian Highlands, Laurentian (Canadian) Shield, Deccan
Lava (volcanic)	Built by layers of hardened lava	Deccan, Columbia, Ethiopian

Tibetan Plateau, the world's largest and highest plateau

• Location: between the Himalaya (south) and the Kunlun (north), mostly in China (Tibet and Qinghai).
• Size: it averages about 4,500 m in height and stretches about 2,500 km from east to west.
• How it formed: the push of the Indian Plate against Eurasia raised the Himalaya and also lifted the whole plateau [4]. The plates are still closing in at about 40–50 mm a year [3].
• "Third Pole": after the Arctic and Antarctic, it holds the largest store of ice. It is also the source of great Asian rivers:

River	Source on or near the plateau	Mouth
Indus	Near Mount Kailash–Mansarovar	Arabian Sea (Pakistan)
Sutlej	Rakas Tal, near Mansarovar	Joins the Indus system (via the Chenab–Panjnad)
Brahmaputra (Yarlung Tsangpo)	Chemayungdung glacier, near Mansarovar	Bay of Bengal (via Bangladesh)
Yangtze	Qinghai–Tibet	East China Sea (Shanghai)
Mekong	Qinghai–Tibet	South China Sea (Vietnam delta)
Yellow (Huang He)	Qinghai	Bohai Sea

• Link to the monsoon:
• In summer the high plateau heats up strongly and warms the air above it.
• This heating helps set up the upper-air wind pattern, including the Tropical Easterly Jet (a fast east-to-west wind high over southern India in summer). It also deepens the low pressure over South Asia.

• The result is a stronger pull of moist south-west monsoon winds from the Indian Ocean.

• In the news: China's Medog (Motuo) dam:

• China has approved a mega dam project on the lower Yarlung Tsangpo (the upper Brahmaputra) in Tibet. The site is near the Great Bend, close to Arunachal Pradesh, where the river enters India as the Siang [2].
• India registered its concerns with China on 30 December 2024. It asked for transparency and for consultation with downstream countries [2].
• India raised the issue again at the Foreign Secretary–Vice Foreign Minister meeting in Beijing on 26–27 January 2025 [2].
• Cross-border river issues are discussed under the Expert Level Mechanism (set up in 2006). The two sides agreed to an early meeting on resuming the sharing of hydrological (river-flow) data [2].
• India says it closely watches developments on the Brahmaputra and takes steps to protect people living downstream [2].
• This is a live issue; check the latest status before the exam.

Other plateaus of the world and India

• Deccan (India): one of the oldest plateaus. Thick lava flows (the Deccan Traps) hardened into basalt (dark volcanic rock), which weathered into black soil (regur), good for cotton.
• East African Plateau: Kenya, Tanzania, Uganda. Known for gold and diamonds (NCERT).
• Ethiopian Highlands: a high volcanic plateau. Source of the Blue Nile (Lake Tana). The Great Rift Valley cuts through it.
• Brazilian Highlands: an old, hard shield in eastern Brazil, rich in iron ore.
• Anatolian Plateau: Turkey, between the Pontic and Taurus ranges.
• Iranian Plateau: Iran, between the Zagros and the Elburz.
• Arabian Plateau: a tilted block, high in the west (Red Sea side) and sloping east towards the Gulf.
• Mongolian Plateau: Mongolia and Inner Mongolia, with the Gobi Desert.
• Colorado Plateau (USA): the Colorado River cut down through its rock layers to form the Grand Canyon.
• Columbia Plateau (USA, north-west): built of thick lava (basalt) flows, like the Deccan.
• Bolivian Altiplano: a high plateau between Andean ridges, with Lake Titicaca.
• Patagonia (Argentina): a dry plateau in the Andes' rain shadow.
• Laurentian (Canadian) Shield: a very old rock base around Hudson Bay, rich in minerals.
• Chhota Nagpur (India, mainly Jharkhand): India's mineral heartland, with coal, iron ore and mica (NCERT).

7. Major plains

• Plain: a large stretch of flat, low land, usually built of soil laid down by rivers. Plains are good for farming, so many people live on them.

Plain	Location	Key fact
North European Plain	France to Russia, up to the Urals	Fertile farmland and dense cities
West Siberian Plain	Russia, Ob–Irtysh basin	Among the flattest large plains on Earth; large marshes
Great Plains	USA–Canada, east of the Rockies	Wheat and cattle
Amazon basin	Brazil and its neighbours	The largest river basin; rainforest
North China Plain	Along the lower Huang He (Yellow River)	Fertile loess (fine wind-blown silt) soils; very densely populated
Mesopotamia	Iraq, between the Tigris and Euphrates	One of the earliest homes of farming and cities
Indo-Gangetic Plain	India, Pakistan, Bangladesh	Home to about 40 crore people (NCERT, Class 6)

8. Great Rift Valley

• Rift valley: a long, sunken strip of land between two parallel faults. It forms where the crust is being pulled apart (a divergent movement).
• Extent: from the Red Sea, through Ethiopia (Afar region), Kenya and Tanzania, to Mozambique.
• How it forms:
• Heat rising from deep below lifts and stretches the crust.
• The crust cracks along faults.

• The middle block sinks and forms a valley.

• Rift lakes: long, narrow and deep lakes such as Tanganyika (Africa's deepest), Malawi (Nyasa) and Turkana.

• Trap: Lake Victoria sits in a shallow basin between the two arms of the rift. It is not a rift lake.

Prelims Hooks

• Andes: about 7,000 km long; seven countries; formed by the Nazca Plate subducting under the South American Plate; highest peak Aconcagua (Argentina).
• Elbrus, a dormant volcano in the Russian Caucasus, is Europe's highest peak. Mont Blanc is the highest peak of the Alps.
• Ranges that meet at the Pamir Knot: Hindu Kush, Karakoram, Kunlun, Tian Shan. The Himalaya joins through the Karakoram. The knot lies mainly in Tajikistan.
• Tirich Mir is the highest peak of the Hindu Kush and lies in Pakistan. The Khyber Pass is in the Spin Ghar, not the main Hindu Kush. The Salang Pass crosses the Hindu Kush.
• Block mountain pairs: the Vosges and the Black Forest are horsts on either side of the Rhine graben.
• Old vs young (trap): Urals, Appalachians, Aravallis and the Great Dividing Range are old. Atlas, Zagros, Andes and Rockies are young.
• Rivers rising on the Tibetan Plateau: Indus, Sutlej, Brahmaputra, Yangtze, Mekong, Huang He. The Ganga does not rise there (it rises at Gangotri in Uttarakhand).
• Lava plateaus: Deccan, Columbia, Ethiopian. Intermontane plateaus: Tibetan, Bolivian Altiplano.
• Grand Canyon is on the Colorado Plateau. The West Siberian Plain lies in the Ob basin.
• Great Rift Valley: Tanganyika, Malawi and Turkana are rift lakes. Victoria is not.

Mains Points

• Plate tectonics and hazards (GS-I/III):
• The young fold belts follow convergent plate boundaries. India and Eurasia still close in at about 40–50 mm a year [3].
• So the Himalaya, Hindu Kush and Andes face earthquakes, landslides and volcanic risk.

• This calls for earthquake-safe buildings, careful planning of dams and roads, and early-warning systems.

• Tibetan Plateau as Asia's "water tower" and climate engine (GS-I/III):

• Its summer heating supports the Indian monsoon.
• Its glaciers feed rivers that serve over a billion people downstream.

• Upstream projects like the Medog dam raise risks of flash floods, changed river flow and data-sharing gaps. India's response so far: registering concerns, using the Expert Level Mechanism and seeking resumed hydrological data [2].

• Mountain passes and geopolitics (GS-I/II):

• The Pamir–Hindu Kush–Khyber corridor shaped invasions, trade and the spread of Buddhism.

• Today it shapes connectivity: the Wakhan Corridor, India's land-border claim with Afghanistan, and the search for routes to Central Asia that avoid Pakistan.

• Plateaus as mineral and settlement zones (GS-I/III):

• Old shields hold most mineral wealth: Chhota Nagpur, Brazilian, Laurentian, East African.
• Lava plateaus give fertile black soils (Deccan).
• Plains hold the most people (Indo-Gangetic: about 40 crore, NCERT), so relief shapes where mining, farming and population cluster.