The great northern plain is situated between the Himalayas in the north and the peninsular plateau in the south, arid and semi-arid plains of Rajasthan in the west to the Ganga delta in the east. It is drained by three river systems.

Extent and stretch:

The great northern plain is situated between the Himalayas in the north and the peninsular plateau in the south, arid and semi-arid plains of Rajasthan in the west to the Ganga delta in the east. It is drained by three river systems.

In the far west are the Beas and the Sutlej draining into the Arabian Sea, the Ganga with its tributaries in the east flowing into the Bay of Bengal and the Brahmaputra in the farther east. It is a vast alluvial plain formed by the rivers.

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The depth of the plain varies from place to place. It stretches from east to west to a distance of 2,400 kms. With a varying width ranging from 240 kms to 320 kms and covers an area of about 250,000 sq. kms. The alluvial deposits include great thickness of sand, clay, loam and silt.

Topography:

The plains are homogeneous with little relief changes for hundreds of kilometers. The Banger i.e. the old alluvium mostly found in the upland region of the plain whereas the Khaddar i.e. the new alluvium are occupied by the lowlands. The uplands in the neighborhood of the rivers are bro­ken into extensive ravine lands extending over thou­sands of kilometers of areas on both sides of the rivers in the southern U.P., eastern Rajasthan and Madhya Pradesh.

Babar and Teri:

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All along the Himalayas where the mountains join the plains, the coarse sand and pebbles brought down from the hills by the swift flowing mountain streams are deposited. These de­posited materials are locally known as Babar. The Babar lands are narrower in the east and extensive in the western and north-western hilly region.

In the Babar region water of “the smaller streams sinks underground and reappears on the surface where the plains begin. This water converts large areas along the rivers into swamps known as Teri, which is largely ill-drained and densely forested. The Teri is more marked in the eastern regions, due to greater rainfall than in the west.

The Western Plains:

The drier parts of the Punjab and Haryana plains extend southwards and gradually merge with the arid plain of Rajasthan which is known as Tharp. This drier region extends for about 640 kms. With an average width of 300 kms covering an area of 1, 75,000 sq. kms. This region is a part of the Indo-Gang etic plain. It was under the sea from perm carboniferous period and was uplifted during the Pleistocene.

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The existence of several dry beds of rivers indicates that the region was once fertile. The river Luna flows through this region. Its water is sweet in the upper reaches and selfish in the lower reaches. There are several salt lakes in the region such as the Samba, Tuchman, Deana, Diana and Pachpadra. Large number of shifting sand dunes occurs in this region.

The Punjab-Haryana plains:

These plains are remarkably flat plains formed by the depositional work of the Sutlej, the Beas, and the Ravi rivers. They extend for 640 kms. From north-east to south­west and 300 kms from west to east, covering an area of 1.75 lakh sq. kms large numbers of low lying flood plains called Bets are found in these regions. The fertile plains found in between two rivers in this region are called Doab. The Bari Doab lies between the Ravi and Beas rivers and the Bits Doab lies between the Beas and Sutlej in this region.

The Ganga plains:

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These plains includes the plains of U.P., Bihar and West Bengal and occupy about 3, 57,000 sq. kms. The Yamuna flows near the western boundary of the plains for about 800 kms. And joins the Ganga at Prayag. The Ganga plains have three sub-regions i.e. the upper Ganga plains, the middle Ganga plains and the lower Ganga plains.

The upper Ganga plains lie north of the Yamuna. The average height of these plains varies in between 100 to 300 meters and covers most part of U.P. It is a vast plain without a hill. It consists of alluvium.

The middle Ganga plain lies partly in U.P. and partly in Bihar. The average height of these plains varies in between 75 to 100 meters. These plains are low level areas containing more Khaddar. The Kisi River flows through region.

The lower Ganga plains include the whole of West Bengal. The average height of these plains is about 50 meters and composed of recent alluvium. The coast of these plains is covered with Tidal forest.

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Brahmaputra plains:

These plains were formed by the river Brahmaputra and its distributaries Sassari, Dibbing and the Lahti. Average height of these plains varies in between 30 to 130 meters and sloping towards south-west, covered with dense forest. The river Brahmaputra originates in Tibet. Its course lies mostly in Tibet where it is known as Tango. It enters to India in Arunachal Pradesh known as Dishing. After the confluence of Lahti, Dishing and Dibbing, it is called the Brahmaputra.

The Plateau:

To the south of the Gangetic plain mainly plateaus are seen in the peninsular India. It extends from Ravalli Hills in the north-west to Nigeria in the south and from the Western Ghats in the west to the Eastern Ghats in its eastern limits. This entire land mass is called the Godwin land and it is a part of a very ancient landmass. Many small plateaus belong in this vast peninsular plateau. Three of those plateaus are to the north of the Vindhya Mountains; those are the Malawi plateau, the Chhotnagpur plateau and the Meghalaya plateau.

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The plateaus to the south of the Vindhyas are known as the South Indian Plateaus. The most important of those are the Deccan Plateaus, the Amarkantaka Plateaus and the Mysore Plateaus. These plateaus are composed of hard igneous rocks and rocks metamorphosed from the igneous rocks. These have been eroded to a great extent by various denuding agents. The Western Ghats, the Eastern Ghats, the Vindhyas, Sapura, Manado and Magical hills etc. come under this region. The Southern Indian Plateaus are divided into two major parts by the Narmada river valley.

Those are: (a) the Central Mountains, and (b) the Southern Plateaus.

(a) The Central Mountains:

The region extending from the north of the Narmada Valley to the North Indian Plains and from the Ravalli Hills in the west to the Chhotnagpur Plateau in the east is known as the Central Mountains. It gradually slopes down to the north to merge into the Gang etic Valley. Its western part is known as the Malawi Plateau and the eastern part as the Chhotnagpur Plateau. There are smaller plateaus like the Reba, the Bundelkhand and the Banlkhand plateaus etc. in the Central Zone of the Malawi Plateaus. The -portion of the Central Mountains in Madhya Pradesh is very old. In course of time this area is being denuded by the Chambal, Beta and Son rivers.

The eastern portion of the Central Mountains is known as the Chhotnagpur Plateag. It extends up to the Gang etic plains in the north and Rajmahal Hills in the east. Beyond Rajmahal Hills, this plateau has been covered with the silts brought by the Ganga and the Brahmaputra the Meghalaya Plateau is situated to the east of these plains. This plateau was, once upon a time, connected with the Chhotnagpur Plateau.

(b) The Southern Plateaus:

The Southern Plateaus extend from the south of the Narmada Valley up to the Nil iris and from the Western Ghats to the Eastern Ghats. It is almost like a triangle. Its length is about 1280 kms. And average height varies from 500 mars to 1000 mars. Its surface is stony. This plateau is gradually sloping down from the west to the east for .which most of the rivers, rising in the Eastern Ghats and flowing eastward drain into the Bay of Bengal. The Godavari is the longest of those rivers.

The other main rivers are the Mahanadi, the Krishna and the Cauvery. The north western part of the plateau belongs in Maharashtra and Karnataka. That part is called the Deccan Plateau or the Deccan Trap. The Southern Plateaus or the Peninsular Pla­teaus are also named as the Amarkantaka Plateau, the Telengana Plateau and the Mysore Plateau in different regions.

Different kinds of minerals are abundantly available as the plateaus-are composed of igneous rock. The hill stations or health resorts of Ootcamand (Booty) of Tamilnadu, Mahabaleshwar of Maharashtra, Panchmari of Madhya Pradesh etc. are located in these plateaus.

The Western Ghats and the Eastern Ghats respectively limit the western and eastern bounda­ries of the Peninsular Plateaus Both the Ghats join with each other in the south at the Nigeria Hills. Dodabetta is the highest (2637 mars.) peak of the Nil iris.

The Western Ghats stand in its western lim­its like a continuous wall. Ana Mud (2,695 mars.) in the State of Kerala is the highest peak of the Western Ghats. The western side of the Western Ghats has a steep rise from the west coast. So it is very difficult to enter into the Southern Plateaus from the ‘west coast region. The Western Ghats can be passed through the Thai Ghat, Abhor Ghat and Pal Ghat passes. Railway lines run through these passes to join the Peninsular Plateau with important towns and ports of the west coast.

The Eastern Ghats demarcate the eastern limits ‘of the Peninsular Plateaus. It is not a continuous chain like the Western Ghats. It is dissected by number of river-valleys of the Mahanadi, the Godavari, the Cauvery and the Krishna. There are many small and big mountains in it. Dermal (1670 mars.) in Orissa is the highest peak of the Eastern Ghats.

Meghalaya Plateau:

This plateau is situated to the south of the Brahmaputra Valley. This is a pan of the Chhotnagpur Plateau and is composed of old hard igneous rock like the Peninsular Plateaus. It is separated from the Chhotnagpur Plateau by the Gang etic Plain