Physiography of India: Himalayas and Northern Plains
Looking at the structure of a house we see wall, foundation and roof separately. The physiography of a country too has different parts: mountains, plains, plateaus, coast and islands.
Physiography means the divisions of a region by height, slope and landforms. India’s five physiographic divisions: Himalayas, Northern Plains, Peninsula, Coastal Plains and Islands.
Key idea 1 : The Himalayas — The Himalayas are young fold mountains of the world. They extend eastward from the Pamir Knot in Tajikistan and are a major mountain system of Asia. In India they extend from Jammu and Kashmir to Arunachal Pradesh. The Himalayas are not one range but many parallel ranges. From south to north: Siwaliks (youngest), Lesser Himalayas, Greater Himalayas (Himadri) and Trans-Himalayas; from south to north they go from young to old. By region they are also divided into Western (Kashmir), Central (Kumaun) and Eastern (Assam) Himalayas.
Key idea 2 : The Northern Plains — This plain lies between the Himalayas and the Peninsula and extends from Rajasthan-Punjab in the west to Assam in the east. Most of it is flat and low-lying. The part east of the Aravalis is the basin of the Ganga, hence the Ganga Plains, sloping eastward. West Bengal and Bangladesh together form the delta of the Ganga-Brahmaputra system; it is called Sundarbans and as per the textbook it is the largest delta in the world.
Key idea 3 : Western desert and Punjab plains — The western part of the Northern Plains has a desert; it is called the Thar Desert or Marusthali and most of Rajasthan comes in it. North of the desert lie the plains of Punjab; they lie west of the Aravalis and Delhi ranges and were formed by the depositional work of the Sutlej and its tributaries. Their slope is towards the west. As the soil is fertile, agriculture is practised on a large scale here.
- Easy : The youngest Himalayan range? — Siwaliks.
- Medium : Slope of the Ganga Plains is towards? — East.
- Exam-type : Thar Desert mostly in which state? — Rajasthan.
In the figure: Parallel Himalayan ranges from south to north.
Si-Le-Gr-Tr.
The Himalayas are not a single range; they are a system of many parallel ranges.
Memory clue: Himalayas: Siwalik → Lesser → Greater → Trans. Memory clue: "Si-Le-Gr-Tr".
Spot the difference
| Division | Location | Feature |
|---|---|---|
| Himalayas | North | Young fold mountains, parallel ranges |
| Ganga Plains | East of Aravalis | Eastward slope, fertile |
| Punjab plain/Thar | West of Aravalis | Westward slope; Thar desert |
Practice questions
- 1State the five physiographic divisions of India.
- 2Write the Himalayan ranges from south to north.
- 3Explain the two parts of the Northern Plains.
- 4Write information on the Sundarbans.
- 5State the location of the Thar Desert.
- 6How were the Punjab plains formed?
- 7Why are the Himalayas called fold mountains?
- 8Show the Himalayan ranges and Northern Plains on a map.
Show answers (try them yourself first)
- 1Himalayas, Northern Plains, Peninsula, Coastal Plains, Islands.
- 2Siwaliks, Lesser, Greater, Trans-Himalayas.
- 3Ganga Plains east of Aravalis and Punjab-Rajasthan parts to the west.
- 4Ganga-Brahmaputra delta, West Bengal and Bangladesh; as per book the largest.
- 5South of Punjab, in Rajasthan.
- 6By the depositional work of the Sutlej and tributaries.
- 7Because they formed by folding of the Earth’s crust.
- 8Student shows on the map.
Physiography of India: Peninsula, Coast and Islands
A triangular piece of land surrounded by water on two sides is a peninsula. The southern part of India is like that.
The Peninsula is the part south of the Northern Plains that tapers towards the Indian Ocean and has many plateaus and hill ranges.
Key idea 1 : The Peninsula — The Peninsula has many plateaus and hill ranges. The Aravalis in the north are the oldest fold mountains here. There is a series of plateaus bordering the Plains, the Vindhya and Satpura ranges in the central part and the hilly regions of Western Ghats and Eastern Ghats in the west and east. The Western Ghats are the major water divide of the Peninsula.
Key idea 2 : Coastal plains — India has a coastline of about 7,500 km. There are marked differences between the western and eastern coasts. The western coast borders the Arabian Sea and is mostly rocky and narrow; rivers from the Western Ghats are short and swift, so they form estuaries instead of deltas. The eastern coast borders the Bay of Bengal and has been formed by the depositional work of rivers; because of gentle slope rivers flow slowly and deposit sediments, so deltas are found here.
Key idea 3 : Islands — India has small and large islands near the mainland coast. In addition there are two large island groups: Lakshadweep in the Arabian Sea and Andaman and Nicobar Islands in the Bay of Bengal. Most Lakshadweep islands are atolls, small and low. The Andaman group islands are mainly volcanic, large and hilly inside; Barren Island has the only active volcano in India (as per the textbook). There are atolls in the Nicobar group too.
- Easy : Why no deltas on the western coast? — Rivers short and swift; estuaries form.
- Medium : Type of Lakshadweep islands? — Coral (atolls).
- Exam-type : Oldest mountains in the Peninsula? — Aravalis.
In the figure: Differences between western and eastern coasts.
West estuary, East delta.
Though rivers meet the western coast, deltas do not form there; estuaries form.
Memory clue: West = estuary; East = delta. Memory clue: "West estuary, East delta".
Spot the difference
| Point | Western coast | Eastern coast |
|---|---|---|
| Sea | Arabian Sea | Bay of Bengal |
| Width and nature | Narrow, rocky | Wide, formed by deposition |
| River mouths | Estuaries | Deltas |
Practice questions
- 1Describe the Indian Peninsula.
- 2Compare the western and eastern coasts.
- 3Why are the Western Ghats called a water divide?
- 4State the difference between Lakshadweep and Andaman-Nicobar islands.
- 5Why are deltas found on the eastern coast?
- 6Write the features of the Aravali range.
- 7What is Barren Island known for?
- 8Show ghats, plateaus and islands on a map of India.
Show answers (try them yourself first)
- 1Tapering region south of the plains with plateaus and hill ranges.
- 2West: narrow, rocky, estuaries; East: wide, deltas.
- 3Because it divides the waters of Peninsular rivers east-west.
- 4Lakshadweep coral islands; Andaman mainly volcanic islands.
- 5Gentle slope makes rivers slow and deposit sediment.
- 6Oldest fold mountains; north-west Peninsula.
- 7Only active volcano of India (as per the book).
- 8Student shows on the map.
Physiography of Brazil
Some villages have high hills everywhere, others flat farming plains. Most of Brazil is plateau and low hills; there are no very high mountains.
Brazil’s five physiographic divisions: Highlands, Great Escarpment, Coastal region, Plains and Islands.
Key idea 1 : Highlands and Great Escarpment — A large part of Brazil is occupied by highlands, plateaus and small mountains; there are no very high and long mountain ranges. The extensive plateau in the south is known as the Brazilian Highlands, and the Brazilian and Guyana Highlands together form the core of the South American continent. The steep slope on the eastern side of the highlands is the Great Escarpment; it occupies a small area but is a separate division because of its slope and effect on climate. It blocks the south-east trade winds and a rain-shadow area is formed in the north-east; it is called the ‘Drought Quadrilateral’.
Key idea 2 : Plains and Pantanal — In Brazil wide plains are only at two places: the Amazon basin in the north and the Paraguay-Parana source region in the south-west. The Amazon plain lies between two highlands and is Brazil’s largest plain; it is about 1,300 km wide in the west and narrows eastward. Most of it is covered by dense rainforests and is hard to access because of frequent floods and dense undergrowth. The Pantanal is one of the largest wetlands in the world; it is a region of swamps and marshes in the south-west.
Key idea 3 : Coast and islands — Brazil has a coastline of about 7,400 km; it has two parts, northern and eastern. The northern coast has the mouths of many rivers including the Amazon so it is low-lying and Marajo Island lies there. The eastern coast receives many small rivers; the Sao Francisco is the only major river. The coast is known for many beaches and sand-dune complexes. Islands are of two types: coastal (mostly formed by deposition) and marine islands (once part of the mainland, more than 300 km away, tops of submerged mountains).
- Easy : Largest plain of Brazil? — Amazon plain.
- Medium : Drought Quadrilateral because of? — Escarpment blocks winds, rain shadow.
- Exam-type : A large wetland of the world? — Pantanal.
In the figure: Physiographic divisions of Brazil.
The textbook gives the highest peak of Brazil, Pico da Neblina, as 3,014 m; as per newer measurement (2016, IBGE) it is about 2,995 m (as per several sources; check with the book).
Hi-Es-Pl-Co-Is.
Brazil has no high mountain ranges; most of it is plateau and hills.
Memory clue: Brazil = plateau + escarpment + Amazon plain + long coast. Memory clue: "Plateau above, Amazon below".
Spot the difference
| Division | Location | Feature |
|---|---|---|
| Highlands | South and north | Plateau, up to about 1,000 m |
| Great Escarpment | East side of highlands | Steep slope, rain shadow |
| Plains | Amazon basin, Pantanal | Low, rainforest, wetland |
Practice questions
- 1State the physiographic divisions of Brazil.
- 2What is the Great Escarpment and its effect on climate?
- 3Write the features of the Amazon plain.
- 4What is the Pantanal?
- 5Explain the two parts of Brazil’s coast.
- 6State the difference between the physiography of Brazil and India.
- 7Write the types of islands of Brazil.
- 8Write ten sentences on the physiography of Brazil.
Show answers (try them yourself first)
- 1Highlands, Great Escarpment, coastal region, plains, islands.
- 2Steep eastern side of highlands; blocks winds, rain shadow.
- 3Largest, low, rainforest, floods and undergrowth.
- 4A vast swamp and marsh region in the south-west.
- 5Northern (low, many river mouths) and eastern (sand beaches).
- 6India has Himalayas and plains; Brazil mostly plateau and no very high mountains.
- 7Coastal and marine islands.
- 8Student writes sentences on the above points.
Drainage of India and Brazil
Rainwater goes from roof to gutter and then out through a pipe. Likewise water on hills and plains goes to the sea through a network of rivers; this network is called drainage.
Drainage is the network formed by rivers, their tributaries and catchment area. Catchment area is the region whose water goes to one river.
Key idea 1 : Drainage of India — Rivers of India are divided by source into Himalayan and Peninsular groups. Among Himalayan rivers the Indus and its tributaries (Jhelum, Chenab, Ravi, Sutlej) drain Jammu and Kashmir and Ladakh. The Ganga and its tributary Yamuna (source Yamunotri) and the Brahmaputra; the Brahmaputra is known as Tsangpo in Tibet, Dihang in India and then Brahmaputra. The huge water and sediment of the Ganga-Brahmaputra formed a large delta. Peninsular rivers such as Chambal, Ken, Betwa, Son and Damodar join the Ganga basin.
Key idea 2 : Peninsular rivers — Peninsular rivers are rain-fed and are divided into east-flowing (meeting the Bay of Bengal) and west-flowing (meeting the Arabian Sea). The Western Ghats are a major water divide. East-flowing: Mahanadi, Godavari, Krishna and Kaveri; Godavari, Krishna and Kaveri originate on the eastern slopes of the Western Ghats. By catchment area the Godavari is the second largest river system of India; major tributaries of the Krishna are Bhima and Tungabhadra; the Kaveri flows through Karnataka and Tamil Nadu and its water has been used for irrigation since long. West-flowing rivers are short and swift and found in Kerala, Karnataka, Maharashtra and south Gujarat; the Narmada and Tapi are notable exceptions that flow west through rift valleys, and the Luni rises on the western slope of the Aravalis in Rajasthan and joins the Gulf of Kutch.
Key idea 3 : Drainage of Brazil — Brazil has three major river basins: (1) The Amazon basin; the Amazon originates on the eastern slopes of the Andes in Peru; because of its huge flow sediments are not deposited near the mouth; so there is no network of distributaries at the mouth but a series of islands formed in the sea; the channel is about 150 km wide at the mouth; most of the course is navigable. (2) The Paraguay-Parana system in the south-west; these rivers and the Uruguay river join the River Plate in Argentina. (3) The Sao Francisco, the third important river of Brazil; its entire basin is within Brazil; it flows north for about 1,000 km and then turns east to meet the Atlantic Ocean. In addition there are short coastal rivers; as the coast is densely populated they are important.
- Easy : An east-flowing Peninsular river? — Godavari.
- Medium : Why no delta at the Amazon mouth? — Huge flow, sediment not deposited.
- Exam-type : Where is the Sao Francisco basin? — Entirely in Brazil.
In the figure: Major river systems of India and Brazil.
Textbook table: Ganga – length 2,525 km, catchment about 10.16 lakh sq km, discharge 16,648 cu m/s; Amazon – length 6,400 km, catchment about 70.5 lakh sq km, discharge about 2,09,000 cu m/s. As per other sources the Amazon catchment is about 7.05 million sq km, average discharge about 209,000 cu m/s and length 6,400 to 6,992 km (differs by measurement) (check with the book).
Hi-Pe-Am-Pa.
Deltas do not form at the mouth of every river; not at the Amazon mouth.
Memory clue: India = Himalayan + Peninsular; Brazil = Amazon + Parana + Sao Francisco. Memory clue: "Hi-Pe / Am-Pa-Sa".
Spot the difference
| Point | Ganga | Amazon |
|---|---|---|
| Length | 2,525 km | About 6,400 km |
| Catchment | About 10.16 lakh sq km | About 70 lakh sq km |
| At mouth | Large delta | Series of islands, no delta |
Practice questions
- 1How are rivers of India classified?
- 2State the difference between Himalayan and Peninsular rivers.
- 3Compare the Ganga and Amazon basins.
- 4State the three river basins of Brazil.
- 5Why are there no distributaries near the Amazon mouth?
- 6Write the importance of the Kaveri river.
- 7Write the features of west-flowing Peninsular rivers.
- 8Draw the Ganga and Amazon basins on tracing paper.
Show answers (try them yourself first)
- 1By source: Himalayan and Peninsular.
- 2Himalayan: perennial, snow and rain; Peninsular: rain-fed, east/west flowing.
- 3Amazon catchment and discharge much larger; Ganga delta; etc.
- 4Amazon, Paraguay-Parana, Sao Francisco.
- 5The flow is so large that sediment is not deposited.
- 6Irrigation since the 2nd century; dam and canals in the Kaveri delta still work.
- 7Short, swift, form estuaries.
- 8Student draws the maps.