Mountains, plateaus and plains: major landforms and life

Detail

1. The three major landforms and Davis's cycle

• Landform: a natural shape of the land surface, such as a mountain, plateau, plain or valley.
• The three major landforms are mountains, plateaus and plains. Deserts are often studied as a fourth type.
• Two kinds of forces shape them:
• Endogenic forces (forces from inside the Earth) fold, fault and lift the land. They build mountains and raise plateaus.

• Exogenic forces (forces on the surface: rivers, groundwater, glaciers, waves and wind) wear the land down. This wearing down is called gradation.

• Davis's cycle of erosion (W. M. Davis: a landscape passes through three stages as erosion wears it down):

• Youth: high land, steep slopes, deep V-shaped valleys. Example: the Himalaya.
• Maturity: the land is cut into many valleys and the slopes are gentler.
• Old age: the land is worn down to a low, almost flat surface called a peneplain. Only a few hard-rock hills, called monadnocks, still stand.
• The Aravali and other relict hills of Peninsular India are near the old-age stage.

Feature	Mountain	Plateau	Plain
Height	Much higher than the land around it	Raised land, often hundreds to thousands of metres high	Mostly under 300 m
Top	Narrow summit	Broad and more or less flat	Flat or gently rolling
Sides	Steep slopes and a broad base	At least one steep side	Almost no slope
Main life	Terrace farming, herding, tourism, pilgrimage	Mining, some farming on black soil	Intensive farming, dense population
Indian example	Himalaya, Western Ghats	Deccan, Chhota Nagpur	Ganga plain

2. Mountains

• Mountain: land much higher than its surroundings, with a broad base, steep slopes and a narrow summit.
• Most mountains lie in long ranges (chains of mountains), such as the Himalaya (Asia), the Alps (Europe) and the Andes (South America).
• Some peaks stand alone. Kilimanjaro (Tanzania, East Africa) is an isolated volcanic mountain.

Important peaks

Peak	Range / setting	Location	Note
Everest	Great Himalaya	Nepal–China (Tibet) border	8,848.86 m (joint China–Nepal survey, announced December 2020) (NCERT: 8,848 m). Highest in the world
Kanchenjunga	Great Himalaya	Nepal–Sikkim border	Highest peak in India
Aconcagua	Andes	Argentina	Highest peak in South America
Kilimanjaro	Isolated volcano	Tanzania	Highest peak in Africa
Mont Blanc	Alps	France–Italy border	Highest peak in the Alps
Anamudi	Anaimalai Hills, Western Ghats	Kerala	Highest peak in South India, about 2,695 m

Young and old mountains

Feature	Young fold mountains	Old, worn mountains
Shape	Tall, sharp, jagged peaks	Low and rounded
Process	Still rising as the Indian plate pushes into the Eurasian plate	Worn down by erosion over hundreds of millions of years
Davis stage	Youth	Old age
Example	Himalaya, Alps, Andes	Aravali (one of the oldest ranges in the world)

• Relict mountain: a very old range that erosion has worn into low, broken hills. Only stumps of the old range remain.
• Aravali: Gujarat–Rajasthan–Haryana–Delhi.
• Nallamala: Andhra Pradesh–Telangana. Veliconda and Palkonda: Andhra Pradesh. These three are part of the Eastern Ghats.
• Javadi: Tamil Nadu (Eastern Ghats).
• Mahendragiri: Odisha, the highest part of the northern Eastern Ghats.
• Satpura: Madhya Pradesh–Maharashtra.
• (See india-structure-physiography for more.)

Life in the mountains

• Terrace farming: steps are cut into the slopes so water and soil do not wash away. It is used for rice and tea in the Himalaya and the North-East.
• Herding and transhumance (herders move with their animals to high pastures in summer and back to the valleys in winter). Examples: the Gaddis of Himachal Pradesh and the Gujjar-Bakarwals of Jammu and Kashmir.
• Tourism and pilgrimage: hill stations such as Shimla and Darjeeling; shrines such as Kedarnath, Badrinath and Amarnath.
• Mountains are thinly populated because of the cold climate, thin soil and steep slopes.
• Hazards:
• Landslides: steep slopes, heavy rain and road-cutting loosen the soil and rock.
• Avalanches: masses of snow slide down slopes.
• Cloudbursts: very heavy rain falls on a small area in a short time.
• Flash floods: cloudbursts or glacial lake bursts send sudden floods down narrow valleys.
• (See natural-hazards-disasters.)

3. Plateaus

• Plateau: raised land with a more or less flat top and at least one steep side standing above the land around it.
• Tibetan Plateau:
• About 4,500 m high and nearly 2,500 km from east to west.
• It is called the "Roof of the World" and is the highest plateau on Earth.

• It lies between the Himalaya to the south and the Kunlun Mountains to the north.

• Deccan Plateau:

• It is one of the oldest landmasses on Earth.
• Large parts, called the Deccan Traps, are made of hardened lava. The lava flowed out of cracks in the crust about 65 million years ago.
• It is bounded by the Western Ghats and the Eastern Ghats.

"Storehouses of minerals"

• Very old rocks, and rocks that have been heated and squeezed, hold many metallic minerals.

Plateau	Minerals
East African Plateau	Gold, diamonds
Chhota Nagpur Plateau (Jharkhand, Odisha, Chhattisgarh, West Bengal)	Iron ore, coal, manganese
Western Plateau of Australia	Gold, iron

Soil

• Most plateaus have thin, rocky soil that is not very fertile.
• Lava plateaus are an exception:
• Basalt rock weathers (breaks down slowly in place).
• It forms black soil (regur), which is rich in clay and holds moisture well.
• This makes the Deccan suitable for cotton.

Waterfalls

• A river leaves the plateau edge over a steep side, and a waterfall forms.

Waterfall	River	Location
Victoria Falls	Zambezi	Zambia–Zimbabwe border, Africa
Hundru	Subarnarekha	Near Ranchi, Chhota Nagpur, Jharkhand
Jog (Gersoppa)	Sharavati	Shivamogga–Uttara Kannada, Karnataka
Nohkalikai	Plunge stream	Near Sohra (Cherrapunji), Meghalaya Plateau

4. Plains

• Plain: a large area of flat or gently rolling land, generally below 300 m.
• How river plains form:
• Rivers flow down from the mountains carrying silt, sand and clay.
• When the slope becomes gentle, the river slows down and drops this load.
• Floods spread fresh layers of soil over the land.

• Over time this builds a wide, fertile floodplain.

• Ganga plain:

• It lies between the Himalaya and the Peninsular Plateau and runs from Uttar Pradesh to Bihar and West Bengal.

• About 40 crore people live there (NCERT, Class 6).

• Why plains hold large populations:

• Fertile soil.
• Flat land for farming, roads and railways.

• Easy irrigation from rivers and wells.

• Crops: rice, wheat, maize, cotton and jute (jute mainly in the lower Ganga–Brahmaputra delta).

• Problem:
• Heavy tube-well irrigation draws water faster than rain can refill it.

• As a result, the groundwater level is falling, especially in Punjab, Haryana and western Uttar Pradesh.

• World examples: the Indo-Gangetic plain (South Asia), the Yangtze plain (China) and the Mississippi plain (USA).

5. Deserts

• Desert: an area with very little rainfall and scanty plant life.

Type	Example	Location
Hot desert	Sahara	North Africa, the largest hot desert
Hot desert	Thar	Rajasthan (India) and Pakistan
Cold desert	Gobi	Mongolia–China
Cold desert	Antarctica	South Pole, the largest desert overall
Cold desert (India)	Ladakh, Lahaul–Spiti	Rain-shadow of the Great Himalaya

6. Landforms in Indian culture: the five tinais

• Tinai: a landscape type in Sangam Tamil poetry. Each tinai has its own people, work, gods and mood. It is an early Indian way of classifying landforms.

Tinai	Landform	Typical life
Kurinji	Mountains	Hunting and gathering honey
Mullai	Forest and grassland	Herding (pastoral)
Marudam	Plains (river valleys)	Wet-rice farming, settled villages
Neydal	Coast	Fishing and salt-making
Palai	Arid, dry land	Raiding and travel

7. How landforms shaped history

• River plains and civilisation:
• The Indus and Ganga plains gave water, fertile soil and easy movement.

• This supported early cities and kingdoms such as Harappa and Magadha.

• Himalaya as a barrier:

• The range protected India from cold Central Asian winds and from invaders.

• Passes still allowed contact. The Khyber Pass (Pakistan–Afghanistan) was the main route for traders and armies coming from the north-west.

• Thar Desert and trade: caravan routes crossed the Thar and linked Gujarat ports with north India and Central Asia.

8. Geoheritage: protecting landforms

• Geoheritage site: a rock, fossil or landform that is important for understanding the Earth's history and is worth protecting for study, teaching and tourism.
• The Geological Survey of India (GSI), under the Ministry of Mines, declares geo-heritage sites / National Geological Monuments so they can be protected and maintained [2]. GSI keeps adding sites, so the total count keeps changing.

Site	State	Feature
Lonar crater	Buldhana district, Maharashtra	A crater made by a meteorite hitting the Deccan basalt. It is a notified National Geo-heritage Monument [3]
Siwalik Fossil Park	Saketi, Sirmaur, Himachal Pradesh	Fossils of animals with backbones from the Siwalik rocks. It is listed among GSI's Himalayan geo-heritage sites [4]
St Mary's Island	Near Malpe, Udupi, Karnataka	Columnar basalt (lava that cooled and cracked into six-sided pillars)
Marine Fossil Park	Rajasthan	Fossils of sea life

• Lonar is also a Ramsar site (2020):
• It is an endorheic basin (a closed basin whose water has no outlet to the sea).
• The basin is almost circular and lies on the Deccan Plateau [5].

• In April 2023 India had 75 Ramsar sites covering 1.33 million hectares [6].

• In 2023, GSI ran a cleanliness (Swachhata) campaign at 15 geo-heritage sites across the country [7].

• In 2022 the Ministry of Mines released the draft Geo-heritage Sites and Geo-relics (Preservation and Maintenance) Bill. It would allow geo-heritage sites and geo-relics of national importance to be declared and protected by law.
• UNESCO Global Geopark: a UNESCO-recognised area where geological heritage is protected and used for education and local tourism. India has none so far.

Prelims Hooks

• Everest: 8,848.86 m (joint China–Nepal survey, announced December 2020). The older figure is 8,848 m.
• Kanchenjunga is on the Nepal–Sikkim border. Anamudi (Kerala) is the highest peak in South India. Kilimanjaro is an isolated peak, not part of a range.
• Peak–range pairs: Aconcagua–Andes; Mont Blanc–Alps; Anamudi–Anaimalai (Western Ghats).
• Relict-hill traps: Mahendragiri → Odisha; Javadi → Tamil Nadu; Nallamala, Veliconda, Palkonda → Andhra Pradesh. Satpura is a relict range, not a young fold range.
• Waterfall–river pairs: Victoria–Zambezi; Jog–Sharavati; Hundru–Subarnarekha. Nohkalikai is in Meghalaya.
• "Roof of the World" = Tibetan Plateau (about 4,500 m). "Storehouse of minerals" = plateaus such as Chhota Nagpur (iron, coal, manganese) and East Africa (gold, diamonds).
• Tinai–landform: Kurinji–mountains; Mullai–forest/grassland; Marudam–plains; Neydal–coast; Palai–arid land.
• Lonar crater is a meteorite impact crater on Deccan basalt in Buldhana, Maharashtra. It is both a National Geo-heritage Monument [3] and a Ramsar site [5].
• Cold deserts: Gobi, Antarctica, Ladakh. The Thar is a hot desert.
• Davis cycle: youth → maturity → old age (peneplain, with monadnocks left standing). The Aravali is near the old-age stage.

Mains Points

• Why plains carry dense populations (GS-I):
• Fertile alluvium, flat land and easy irrigation support food production.
• About 40 crore people live in the Ganga plain.

• The same pressure has caused groundwater depletion (Punjab, Haryana, western UP), waterlogging and floods. Responses include crop diversification, micro-irrigation and aquifer recharge.

• Mountains: rich in resources but fragile (GS-I/III):

• Young Himalayan slopes are still rising and unstable.
• Road-building, hydropower and crowded pilgrimage routes increase the risk of landslides, cloudbursts and flash floods.

• This calls for hazard zoning, slope-stability studies and limits on carrying capacity (the number of visitors an area can safely hold).

• Plateaus as mineral and energy bases (GS-III):

• Chhota Nagpur's iron, coal and manganese support Indian industry.

• Mining has also caused forest loss, tribal displacement and degraded land. This makes rehabilitation, the District Mineral Foundation and mine closure plans important.

• Geoheritage as a missing protection layer (GS-I/III):

• GSI declares National Geological Monuments [2], but India has no dedicated law yet (the Geo-heritage Bill was released as a draft in 2022).
• India also has no UNESCO Global Geopark.
• Sites such as Lonar [3][5] show how protecting geology can also support wetland conservation, tourism and local jobs.