The Narmada and the Tapi form estuaries rather than deltas mainly because they:

Flow west through rift valleys over hard rock and carry little sediment into a steep coast

Enter the Bay of Bengal, where tides are weak

Which of the following are characteristics of the Himalayan rivers? Select all that apply.

Perennial flow fed by snowmelt as well as rain

Frequent shifting of courses in the plains

Deep gorges cut through the mountains

Fixed courses in broad, shallow, graded valleys

Perennial flow fed by snowmelt as well as rain

Frequent shifting of courses in the plains

Deep gorges cut through the mountains

According to the jet-stream explanation of the Indian monsoon, its sudden onset in early June is associated with:

The northward jump of the subtropical westerly jet to the north of the Tibetan plateau

The arrival of western disturbances

The formation of a high-pressure cell over the Ganga plain

The southward shift of the subtropical westerly jet to the south of the Himalaya

The northward jump of the subtropical westerly jet to the north of the Tibetan plateau

Winter rainfall in north-western India, important for the rabi wheat crop, is brought mainly by:

Tropical cyclones from the Arabian Sea

The retreating north-east monsoon

Assertion (A): Black (regur) soils retain moisture well and suit dry-farmed cotton. Reason (R): They are rich in montmorillonite clay, which swells when wet and holds water. Choose the correct option.

Both A and R are true, and R is the correct explanation of A

Both A and R are true, but R is not the correct explanation of A

Laterite soils are formed mainly by:

Intense leaching under high temperature and heavy rainfall

Deposition by rivers in flood plains

Weathering of basalt in a semi-arid climate

Accumulation of salts through poor drainage

Geography of India I: Physiographic Regions, Himalayan and Peninsular Drainage, Climate, the Monsoon Mechanism, Jet Streams, the Himalayan Cryosphere and Natural Resources

Unit X, the Geography of India, takes three chapters. This first one covers the physical base the document names: major physiographic regions and their characteristics; the drainage system (Himalayan and Peninsular); climate — seasonal weather characteristics, climatic divisions, the Indian monsoon (mechanism and characteristics), jet streams and the Himalayan cryosphere; and the types and distribution of natural resources — soil, vegetation, water, mineral and marine resources. This platform's shared geography course surveys the physical geography of India at an introductory level; this chapter goes to postgraduate depth, from the Himalayan thrust belts and Burrard's divisions to the competing theories of the monsoon, the Somali jet and the state of Himalayan glaciers.

1. Major physiographic regions and their characteristics

India has six physiographic divisions: the northern mountains, the northern plains, the peninsular plateau, the Indian desert, the coastal plains and the islands. The Himalaya, a young fold-mountain system raised by the collision of the Indian and Eurasian plates, runs in parallel ranges separated by major thrust faults. North of the Indus–Tsangpo suture lie the Trans-Himalaya (Karakoram, Ladakh and Zaskar ranges). The Greater Himalaya (Himadri), averaging about 6,000 m with India's highest peak Kanchenjunga (8,586 m), is separated by the Main Central Thrust from the Lesser Himalaya (Himachal) — the Pir Panjal, Dhauladhar and Mahabharat ranges, with most hill stations — which is separated by the Main Boundary Thrust from the Shiwaliks, the outermost foothills of unconsolidated sediments with longitudinal valleys called duns (Dehradun); the Himalayan Frontal Thrust marks their contact with the plains. Sir Sidney Burrard divided the range from west to east by rivers: the Punjab (Kashmir–Himachal) Himalaya between the Indus and the Satluj, the Kumaon Himalaya between the Satluj and the Kali, the Nepal Himalaya between the Kali and the Tista, and the Assam Himalaya between the Tista and the Dihang. The range bends sharply at its ends — the syntaxes of Nanga Parbat and Namcha Barwa — and continues in the north-east as the Purvanchal hills (Patkai, Naga, Manipur and Mizo hills).

The northern plains of the Indus, Ganga and Brahmaputra were built of alluvium, several kilometres thick, in the foredeep in front of the rising Himalaya. From north to south they show four belts: the bhabar, a narrow porous belt of pebbles at the foot of the Shiwaliks where streams sink underground; the terai, a marshy, formerly forested belt where they re-emerge; the bhangar, older alluvium on higher ground with calcareous kankar nodules; and the khadar, newer alluvium of the flood plains renewed every year. The peninsular plateau, the oldest landmass, is a stable block of Precambrian rocks and Gondwana sediments, divided by the Narmada into the Central Highlands (Malwa, Bundelkhand, Baghelkhand, Chotanagpur) and the Deccan Plateau, with the Deccan Traps in the north-west. It is flanked by the Western Ghats (Sahyadri) — continuous, higher, with Anamudi (2,695 m) the highest peak of the peninsula — and the Eastern Ghats, discontinuous and cut through by the east-flowing rivers; the Aravalli, among the oldest fold mountains in the world, runs across Rajasthan. The west coastal plain (Kachchh, Kathiawar, Konkan, Kannada, Malabar with its lagoons called kayals) is narrow and indented, with estuaries rather than deltas; the east coastal plain (Utkal, Andhra, Coromandel) is broad, with the great deltas of the Mahanadi, Godavari, Krishna and Kaveri. The Andaman and Nicobar Islands are the emerged peaks of a submarine range continuing the Arakan Yoma, with the volcanoes Barren and Narcondam; the Lakshadweep islands are coral atolls.

2. Drainage system: Himalayan and Peninsular

Feature	Himalayan rivers	Peninsular rivers
Age and origin	Young; several are antecedent, older than the range they cross (Indus, Satluj, Brahmaputra)	Old; largely consequent on the tilt of the plateau
Regime	Perennial — fed by snow and glacier melt as well as monsoon rain	Seasonal — rain-fed, with low flow in the dry season
Valleys and courses	Deep gorges in the mountains; meandering and frequently shifting courses in the plains (the Kosi has moved westward over a hundred kilometres)	Broad, shallow, graded valleys and fixed courses; waterfalls where they leave the plateau
Mouths	Vast deltas — the Ganga–Brahmaputra delta is the largest in the world	East-flowing rivers form deltas; the west-flowing Narmada and Tapi flow through rift valleys and form estuaries

The Indus system rises near Lake Mansarovar and receives the Jhelum, Chenab, Ravi, Beas and Satluj; under the Indus Waters Treaty (1960) the eastern rivers (Ravi, Beas, Satluj) were allotted to India and the western rivers (Indus, Jhelum, Chenab) to Pakistan. The Ganga begins as the Bhagirathi (from the Gangotri glacier at Gaumukh) and the Alaknanda, which meet at Devprayag; its main right-bank tributary is the Yamuna, which collects the Chambal, Betwa and Ken from the plateau, and its left-bank Himalayan tributaries — the Ramganga, Gomti, Ghaghara, Gandak and Kosi (long called the "sorrow of Bihar") — bring much of its water and sediment, while the Son joins from the south. The Brahmaputra rises as the Yarlung Tsangpo in Tibet, turns round Namcha Barwa, enters India as the Siang or Dihang, is joined by the Dibang and Lohit, and holds Majuli, one of the largest river islands in the world. A hypothesis of Pascoe and Pilgrim (1919) held that a single great river, the Indobrahm or Shiwalik river, once flowed along the foot of the Himalaya and was later dismembered into the Indus, Ganga and Brahmaputra systems. Among peninsular rivers, the Godavari, the longest (often called the Dakshin Ganga), Krishna, Mahanadi and Kaveri flow east to the Bay of Bengal, the Western Ghats forming the main water divide; the Narmada and Tapi flow west through rift valleys. Drainage patterns include dendritic (the plains), trellis (in folded Himalayan belts), radial (the Narmada, Son and Mahanadi from Amarkantak) and centripetal (into Loktak lake in Manipur).

3. Climate, the monsoon mechanism, jet streams and the Himalayan cryosphere

The India Meteorological Department recognises four seasons: the cold weather (January–February), when western disturbances — extratropical depressions steered by the subtropical westerly jet — bring winter rain and snow to the north-west that is vital for rabi wheat; the hot weather (March–May), with the loo in the north-west, nor'westers (Kalbaisakhi) in Bengal and Assam and mango showers in Kerala and Karnataka; the south-west monsoon (June–September), which brings about three-quarters of the annual rainfall; and the post-monsoon or retreating monsoon (October–December), with "October heat", cyclones in the Bay of Bengal and the north-east monsoon rain of Tamil Nadu. The south-west monsoon usually sets in over Kerala about 1 June and covers the whole country by about 8 July; withdrawal begins from western Rajasthan in mid-September. Seasonal rainfall is judged against the long-period average (about 87 cm for June–September); breaks occur when the monsoon trough shifts to the Himalayan foothills, leaving the plains dry while the hills flood. Climatic divisions follow Köppen (Chapter 4 of this course) or Trewartha, and IMD reports by 36 meteorological subdivisions.

Explanation of the monsoon	Mechanism
Thermal (land–sea) theory — Edmund Halley, 1686	Summer heating creates low pressure over the land and draws in moist air from the cooler sea; the reverse in winter — a giant sea breeze. It cannot explain the monsoon's sudden onset, its breaks or its year-to-year variation
Shifting ITCZ — H. Flohn, 1951	The Inter-Tropical Convergence Zone moves north over the Ganga plain in summer (the monsoon trough); the south-east trades cross the equator, are deflected to the right and arrive as the south-west monsoon
Jet streams and the Tibetan heat source — Yin (1949), Koteswaram (1958)	In winter the subtropical westerly jet lies south of the Himalaya and blocks the monsoon; in early June it jumps north of Tibet, the heated Tibetan plateau builds an upper-level high, and a tropical easterly jet appears over the peninsula near 15°N — the monsoon "bursts"
Somali (Findlater) jet and Mascarene High	A low-level cross-equatorial jet off East Africa (described by Findlater, 1969), fed by the Mascarene High in the southern Indian Ocean, carries moisture into the Arabian Sea branch
Teleconnections	El Niño tends to weaken and La Niña to strengthen the monsoon; a positive Indian Ocean Dipole favours it; the Madden–Julian Oscillation modulates active and break spells

The Himalayan cryosphere — glaciers, snow cover and permafrost, often called the "Third Pole" — stores more ice than anywhere outside the polar regions. The Geological Survey of India has inventoried about 9,500 glaciers in the Indian Himalaya; Siachen in the Karakoram (about 76 km) is the longest in India, Gangotri (about 30 km) feeds the Bhagirathi from its snout at Gaumukh, and Zemu is the largest in Sikkim. Most Himalayan glaciers are retreating and thinning, with the Gangotri snout receding at an average of roughly 15–20 m a year over recent decades. Rivers differ in their dependence: the Indus draws a large share of its flow from snow and glacier melt, while the Ganga and Brahmaputra depend more on the monsoon. Retreat multiplies moraine-dammed glacial lakes and the risk of GLOFs — Chorabari lake above Kedarnath in 2013 and South Lhonak in Sikkim in 2023 — and the National Mission for Sustaining the Himalayan Ecosystem under the NAPCC is the policy response.

4. Types and distribution of natural resources: soil, vegetation, water, minerals and marine resources

Soil (ICAR grouping)	Formation and properties	Distribution
Alluvial	River-deposited; khadar (new) and bhangar (old); rich in potash, poor in nitrogen	The northern plains and the deltas — the most extensive group
Black (regur)	Weathered Deccan basalt; rich in montmorillonite clay that swells when wet and cracks when dry; retains moisture; suited to cotton	Maharashtra, Malwa, Gujarat, northern Karnataka and Telangana
Red and yellow	Crystalline igneous and metamorphic rocks; red from ferric oxide, yellow when hydrated	Eastern and southern parts of the peninsula
Laterite	Intense leaching under high temperature and heavy rainfall removes silica and bases, leaving iron and aluminium oxides; hardens on exposure (used for bricks)	Western Ghats, Kerala, the hills of Odisha and the north-east
Arid; saline and alkaline; peaty; forest and mountain	Sandy desert soils; reh, kallar and usar crusts from poor drainage and irrigation; organic peaty soils in waterlogged areas; thin, acidic soils on slopes	Rajasthan; Punjab–Haryana–Uttar Pradesh canal tracts; Kerala and the Sundarbans; the Himalaya

Vegetation follows rainfall: tropical evergreen forest above about 200 cm (Western Ghats, the north-east, the Andamans), moist deciduous at 100–200 cm (sal and teak across much of the peninsula and the Himalayan foothills), dry deciduous at 70–100 cm, thorn forest and scrub below 70 cm, montane forests changing with altitude in the Himalaya and Nilgiris, and littoral and swamp forests including the mangroves of the Sundarbans; Champion and Seth (1968) recognised sixteen type groups. The India State of Forest Report 2023 put forest cover at about 21.8 per cent and forest and tree cover together at about 25.2 per cent of the country's area, against the policy goal of one-third. Water: India has about 18 per cent of the world's people and about 4 per cent of its fresh water; of roughly 4,000 billion m³ of annual precipitation, the Central Water Commission puts utilisable water at about 1,122 billion m³ (690 surface, 432 groundwater), and per-capita availability has fallen below the "water-stressed" line of 1,700 m³; India is the world's largest user of groundwater. Minerals cluster in three peninsular belts: the north-eastern plateau (Chotanagpur and Odisha — coal of the Damodar valley at Jharia and Raniganj, iron ore of Singhbhum and Keonjhar, bauxite of Koraput's Panchpatmali, mica, manganese); the south-western plateau (Karnataka and Goa — iron ore of Bellary–Hospet and Goa); and the north-west (the Aravalli — copper at Khetri, zinc and lead at Zawar). Petroleum comes from Mumbai High offshore, Assam (Digboi) and Gujarat, and natural gas from the Krishna–Godavari basin. Marine resources lie within an exclusive economic zone of about 2 million km² extending 200 nautical miles from the coast: fisheries, offshore oil and gas, beach placers such as the monazite (a thorium ore) and ilmenite sands of Kerala, and polymetallic nodules in the Central Indian Ocean Basin, where India was registered as a pioneer investor in 1987 and which the Deep Ocean Mission (2021) is exploring.

Key takeaways

Trans-, Greater, Lesser and Shiwalik Himalaya separated by the MCT, MBT and HFT; Burrard's Punjab, Kumaon, Nepal and Assam Himalaya divided by the Satluj, Kali and Tista; plains belts bhabar, terai, bhangar, khadar; Western Ghats continuous, Eastern Ghats broken.
Himalayan rivers: antecedent, perennial, shifting, deltaic; Peninsular rivers: old, seasonal, fixed, graded — east-flowing ones form deltas, the Narmada and Tapi estuaries in rift valleys; the Indobrahm hypothesis; radial drainage from Amarkantak.
Monsoon: thermal theory (Halley), shifting ITCZ (Flohn), the northward jump of the westerly jet and the tropical easterly jet over a heated Tibet, the Somali jet, and ENSO, IOD and MJO; onset about 1 June, full cover about 8 July; western disturbances give winter rain.
The Himalayan cryosphere (about 9,500 glaciers; Siachen, Gangotri, Zemu) is retreating, raising GLOF risk (Chorabari 2013, South Lhonak 2023); the Indus depends most on meltwater.
Soils: alluvial, black (montmorillonite), red, laterite (leaching), arid, saline, peaty, mountain; forests about 21.8 per cent (ISFR 2023); utilisable water about 1,122 billion m³; mineral belts in Chotanagpur–Odisha, Karnataka–Goa and the Aravalli; a 200-nautical-mile EEZ of about 2 million km².

Practice questions (14)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

The Greater Himalaya is separated from the Lesser Himalaya by the:
1. Himalayan Frontal Thrust
2. Indus–Tsangpo Suture Zone
3. Main Central Thrust
4. Main Boundary Thrust
Show answer
Answer: C — Main Central Thrust
From north to south: the Indus–Tsangpo suture bounds the Trans-Himalaya, the Main Central Thrust separates the Greater from the Lesser Himalaya, the Main Boundary Thrust separates the Lesser Himalaya from the Shiwaliks, and the Himalayan Frontal Thrust separates the Shiwaliks from the plains.
In Sir Sidney Burrard's regional division of the Himalaya, the Kumaon Himalaya lies between the rivers:
1. Kali and Tista
2. Indus and Satluj
3. Tista and Dihang
4. Satluj and Kali
Show answer
Answer: D — Satluj and Kali
Burrard's divisions are the Punjab Himalaya (Indus to Satluj), Kumaon Himalaya (Satluj to Kali), Nepal Himalaya (Kali to Tista) and Assam Himalaya (Tista to Dihang).
The narrow belt of porous pebbles at the foot of the Shiwaliks, in which streams disappear underground, is the:
1. Khadar
2. Bhabar
3. Terai
4. Bhangar
Show answer
Answer: B — Bhabar
The bhabar is coarse, porous debris where streams sink; they re-emerge in the marshy terai to the south. Bhangar is older and khadar newer alluvium in the plains proper.
Rivers such as the Indus, Satluj and Brahmaputra, which cut deep gorges across the Himalaya because they are older than the ranges, are called:
1. Antecedent rivers
2. Consequent rivers
3. Superimposed rivers
4. Subsequent rivers
Show answer
Answer: A — Antecedent rivers
An antecedent river maintains its course by cutting down as the land rises across its path. Consequent rivers follow the initial slope, subsequent ones develop along weak rock, and superimposed ones were let down from an overlying cover of rock.
The Narmada and the Tapi form estuaries rather than deltas mainly because they:
1. Are fed by Himalayan glaciers
2. Are dammed near their sources
3. Flow west through rift valleys over hard rock and carry little sediment into a steep coast
4. Enter the Bay of Bengal, where tides are weak
Show answer
Answer: C — Flow west through rift valleys over hard rock and carry little sediment into a steep coast
Both flow west through faulted troughs, carry relatively little fine sediment, and reach a coast where strong tides in the Gulf of Khambhat carry deposits away — conditions for estuaries. The east-flowing rivers build deltas on the gentler, low-tide east coast.
Which of the following are characteristics of the Himalayan rivers? Select all that apply.
1. Fixed courses in broad, shallow, graded valleys
2. Perennial flow fed by snowmelt as well as rain
3. Frequent shifting of courses in the plains
4. Deep gorges cut through the mountains
Show answer
Answer: B — Perennial flow fed by snowmelt as well as rain; C — Frequent shifting of courses in the plains; D — Deep gorges cut through the mountains
Himalayan rivers are perennial, cut gorges (several being antecedent) and meander and shift across the plains — the Kosi is the classic case. Fixed courses in shallow, graded valleys are typical of the old peninsular rivers.
According to the jet-stream explanation of the Indian monsoon, its sudden onset in early June is associated with:
1. The arrival of western disturbances
2. The formation of a high-pressure cell over the Ganga plain
3. The southward shift of the subtropical westerly jet to the south of the Himalaya
4. The northward jump of the subtropical westerly jet to the north of the Tibetan plateau
Show answer
Answer: D — The northward jump of the subtropical westerly jet to the north of the Tibetan plateau
In winter the westerly jet lies south of the Himalaya and suppresses the monsoon; its abrupt move north of Tibet in early June, together with the heating of the plateau and the appearance of the tropical easterly jet, allows the monsoon to burst. Western disturbances are a winter phenomenon.
The low-level, cross-equatorial jet off the coast of East Africa that carries moisture into the Arabian Sea branch of the monsoon is the:
1. Polar front jet
2. Somali (Findlater) jet
3. Subtropical westerly jet
4. Tropical easterly jet
Show answer
Answer: B — Somali (Findlater) jet
The Somali jet, described by Findlater in 1969, flows at about 1–1.5 km above the surface from the Mascarene High across the equator and along the Somali coast. The tropical easterly jet flows far higher, near 12–16 km, over the peninsula.
Winter rainfall in north-western India, important for the rabi wheat crop, is brought mainly by:
1. Western disturbances
2. Tropical cyclones from the Arabian Sea
3. Nor'westers
4. The retreating north-east monsoon
Show answer
Answer: A — Western disturbances
Western disturbances are extratropical lows from the Mediterranean region steered by the subtropical westerly jet. The north-east monsoon rains fall on Tamil Nadu, and nor'westers are pre-monsoon storms in the east.
Assertion (A): Black (regur) soils retain moisture well and suit dry-farmed cotton. Reason (R): They are rich in montmorillonite clay, which swells when wet and holds water. Choose the correct option.
1. Both A and R are true, and R is the correct explanation of A
2. Both A and R are true, but R is not the correct explanation of A
3. A is true, but R is false
4. A is false, but R is true
Show answer
Answer: A — Both A and R are true, and R is the correct explanation of A
Both are true and R explains A: the expanding clay stores water through the dry months, and the deep cracks that open as it dries let the soil "plough itself" — the basis of rainfed cotton on the Deccan lava plateau.
Laterite soils are formed mainly by:
1. Intense leaching under high temperature and heavy rainfall
2. Deposition by rivers in flood plains
3. Weathering of basalt in a semi-arid climate
4. Accumulation of salts through poor drainage
Show answer
Answer: A — Intense leaching under high temperature and heavy rainfall
Heavy rain in a hot climate washes out silica and bases and leaves iron and aluminium oxides, giving laterite on the Western Ghats, in Kerala and in the hills of Odisha and the north-east. Weathered basalt gives black soil and poor drainage saline soils.
Gaumukh, the source of the Bhagirathi, is the snout of the:
1. Zemu glacier
2. Satopanth glacier
3. Siachen glacier
4. Gangotri glacier
Show answer
Answer: D — Gangotri glacier
The Bhagirathi emerges from Gaumukh at the snout of the roughly 30-km Gangotri glacier, which has been retreating. Siachen is in the Karakoram, Zemu in Sikkim, and the Satopanth glacier feeds the Alaknanda.
India's exclusive economic zone extends how many nautical miles from its baselines? Type a number.
Numerical answer — type the value.
Show answer
Answer: 200
Under the UN Convention on the Law of the Sea an EEZ extends up to 200 nautical miles, giving India sovereign rights over the resources of about 2 million km² of sea, including fisheries, hydrocarbons and seabed minerals.
Panchpatmali in the Koraput district of Odisha is known for large deposits of:
1. Copper
2. Mica
3. Bauxite
4. Coking coal
Show answer
Answer: C — Bauxite
Panchpatmali's laterite-capped plateau holds one of the largest bauxite deposits in India, supplying NALCO's alumina refinery. Coking coal comes from Jharia, copper from Khetri and Malanjkhand, and mica chiefly from Jharkhand and Andhra Pradesh.