The Great Plains
This plain lies between the Himalayas in the north and Peninsular Plateau in the south. The northern plains have been created by the accumulation of alluvial sediments transported by major rivers such as the Indus, the Ganga, and the Brahmaputra.
- It is known as most densely populated and most fertile plain of the world.
- It covers a total area of 7.8 lakh sq. km.
- These plains extend approximately 3,200 km from the east to the west
- It is widest in the west & Its width decreases in the east and reaches to. It is a monotonous plain. he average width of these plains varies between 150-290 km
- Its highest elevation is 291m between Ambala and Saharanpur.
- It is a watershed area, separating the drainage system of the Ganga from the Indus
Origin and Formation of the Plain
- The notion that this expansive plain is the outcome of extensive sedimentary deposits situated between the Peninsular and the Himalayas is widely acknowledged.
- It is formed after the Himalayan Orogeny.
- The alluvial deposits are so deep, that it is very difficult to ascertain its actual depth.
Origin of Foredeep
- There have been varying opinions put forth concerning the genesis of the major economic downturn and the mechanism by which it was filled.
- Some scholars hold the view that this depression was formed as a geosyncline, which is a remnant of the Tethys Sea. Specifically, the Eastern portion of this geosyncline has been designated as the Eastern Gulf, while the Western portion is known as the Gulf of Sind.
- Edward Suess, the famous Austrian geologist is of such opinion. He suggested that a foredeep was formed in front of the Himalayas.
- It couldn’t furth er extend in south due to inflexible solid landmass of the Peninsula. It was like a syncline, which was filled up by the Himalayan Rivers mainly.
- Another group of scholars is of the view that this foredeep is just like a great deep rift or fracture, which was formed at the time of the elevation of the Himalayas.
- Sir Sydney Burrard has concealed that a fracture in the earth’s sub-crust, several thousand metres deep and 2400 km. long took place at the time of elevation of Himalayan chain. Most of geologists do not agree with this view.
The average gradient of slope between Saharanpur and Kolkata is 20cm per km. It declines towards the middle and lower valley of River Ganga. After Varanasi upto Ganga delta, the average slope is 15 cm. per Km.
Division of Great Plains
On the basis of nature of relief and soil structure the following divisions can be marked in this Great Plain.
(i) The Bhabhar Region-
- Bhabar is a zone adjacent to the Shiwalik foothills.
- In this zone, the slope of the land changes abruptly.
- When streams and rivers from the mountains reach this zone, they deposit large rocks and boulders.
- Sometimes, the water in these streams and rivers may vanish in the Bhabar region due to the porous soil.
- The Bhabhar is a piedmont plain.
- It is comparatively narrow in the east and extensive in the western.
(ii) The Terai Region-
- The area south of the Bhabar is called the Tarai belt, which stretches approximately 10-20 km in width.
- This region is characterized by the emergence of many streams and rivers, which do not have well-defined channels, resulting in marshy and swampy conditions commonly known as the Tarai.
- Most of the Terai Region has been re claimed and turned into the cultivation of rice, sugarcane and wheat.
- This has a luxurious growth of natural vegetation and houses a varied wildlife
(iii) Alluvial Region-
The southern region of Tarai is characterized by two distinct types of alluvial deposits: Bhangar, which refers to the older sedimentary deposits, and Khadar, which refers to the newer ones.
Bangar Alluvium-
The Bangar Alluvium is composed of ancient alluvial deposits that originated during the middle to upper Pleistocene epoch. These deposits can be found in the elevated regions located between two rivers, above the typical flood level.
- The colour is green.
- It is often composed with Calcareous concretions known as Kankar.
- These are highly fertile.
Khadar Alluvium-
It is composed of newer alluvium. It forms flood plains along the river banks. A new layer of alluvium is deposited by river flood every year. These deposits are of the age of upper Pleistocene and Recent period.
- The colour is light. These are good storage of underground water.
- The clays have Kankar and sand.
- These are quite fertile and are normally renewed every year, denoting the increase in fertility.
Reh-
- This is spread in those Bangar areas where the irrigation has the dominance.
- It is known as the white layer of saline efflorescence.
- It is widely extended in drier areas of Uttar Pradesh, and Haryana. It is also known as Kallar.
Bhur-
- It denotes an elevated piece of land situated along the drain areas of Ganga and Ramganga Rivers.
- This has been formed due accumulation of wind-blown winds during the hot dry months of the year
Deltaic Region-
- These are formed on the mouth of rivers. Ganga-Brahmaputra Delta the mouths of these mighty rivers form some of the largest deltas of the world, for example, the famous Sunderbans delta.
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Haryana and Delhi act as a water divide between the Indus and Ganga river systems, while the Brahmaputra river flows from northeast to southwest before turning southward at Dhubri into Bangladesh.
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The alluvial soil of these river valleys is fertile and supports the growth of crops such as wheat, rice, sugarcane, and jute.
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This fertile land helps to sustain a large population.
Regional division of planes
1.Rajasthan Plain-
- This is the western extremity of the Great Plain
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The Rajasthan Plain is situated in western Rajasthan and is bounded by the Aravalli Range to the east and Pakistan to the west. This region is a component of the Marusthali Marwar Plain.
- This desert is an undulating plain.
- It’s slope is towards south and west.
- The topography is marked by a few hills of hard rocks.
- The Sambhar Lake is the largest. is extended at a distance of 65 km. west of Jaipur
The Luni -
- The main River of this region is Luni
- The Luni is a seasonal stream flowing towards south-west of the Rann of Kutch. The north area of Luni Basin has inland drainage with a number of lakes like Sambhar, Didwana, Lun Karansar, Kuchaman and Degna
2.The Punjab-Haryana Plain-
- It is also called Sutlej-Yamuna Divide. It is extended on Punjab, Haryana and Delhi states.
- Sutlej, Ravi and Beas are main rivers. Between Sutlej and the Yamuna, the Ghagghar a seasonal stream is important.
- River Saraswati was perhaps an important perennial river in the past, it disappeared with the change in climate.
- It is bounded by River Yamuna on the east. On south-east Aravalli Ranges are ended near Delhi.
- The area has two regional slopes, westwards to the Indus Plain and southwards to the Rann of Kutch.
Doabs- The Ravi, the Beas and Satluj form Doabs the land between two rivers.
- Bari Doab -The land between Ravi and Beas is called upper Bari Doab,
- Bist Doab -the land between Beas and Sutlej is called Bist Doab
The land in the south of Sutlej is known as Ghagghar Plain. This Ghagghar Plain has developed as a fertile plain because of irrigation facilities.
3.The Ganga Plains-
- The region encompasses Uttar Pradesh, Bihar, and West Bengal.
- The land slopes west to east and southeast.
- The Ganga river is the primary watercourse in the area.
- Important tributaries include Yamuna and Son on the right bank and Ghaghra, Gandak, and Kosi on the left bank.
- The region has two primary physiographic variations: Bhangar and Khadar.
- Beel - Dead arms of rivers, filled up with water are called Beel.
It has three main sub -divisions-
(i) Upper Ganga Plain-
- It is between Shiwalik Hills in the north and Peninsular Plateau in the south. The slope is steep in north as compared to south and east parts. Yamuna, Ganga, Ramganga, Sharda, Gomti, Ghaghra are the main rivers.
(ii) Middle Ganga Plain-
It is extended on east U.P. and Bihar.
- Sorrow of Bihar - The plain is highly affected by the shifting of courses of rivers, causing floods. Kosi is a bad name, and called Sorrow of Bihar.
- Ghaghra, Gandak, Kosi and Ganga are main rivers. It has great occurrence of Khadar land. Kankar formation is less. It is highly fertile. It is decorated with ox -bow lakes and dead arms of rivers. Floods are the regular feature.
(iii) Lower Ganga Plain-
- It includes the whole of West Bengal excluding Purulia district in the west and the hilly parts in the north.
- It is drained by Tista, Jaldhaka and Torsa rivers. The plain is narrowed down near Raj Mahal hills; it is formed in Pleistocene period and subsequently upwarped and eroded into terraces.
- Its most of the part is composed of recent alluvium. The seaward face of the delta is strongly influenced by tidal estuaries resulting into a maze of sand banks, mud flats, mangrove swamps.
- It is covered with tidal forests called Sundarbans.
4.Brahmaputra Plains-
- This is also known as Assam valley. It is low level narrow plain lying between Meghalaya Plateau and Himalaya Mountain.
- The direction of slope is towards south -west. Terai and semi-terai regions exist on the northern fringe of the Plains. These are covered with swampy soil and dense forests. This Plain is the soul of India.
- It is most densely and prosperous part of the country. This has high significance for agriculture, trade, industry and transport.