Indo-Gangetic Plains| Class 11 Geography Notes

Class 11 Geography Indo-Gangetic Plains Notes: Geography Class 11 Notes is an important subject in the Social Science curriculum that requires students to have a thorough understanding of the Earth, its physical features, and human activities. The subject demands a strong foundation in conceptual knowledge and an ability to analyze and interpret geographical data. These notes provide a comprehensive summary of the key topics, aiding students in better comprehension of the subject matter.

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Indo-Gangetic Plains| Class 11 Geography Notes

Indo-Gangetic Plains

The Indo-Gangetic Plains also referred to as the Indo-Gangetic-Brahmaputra Plains or the Great Plains of North India, are formed by the accumulation of alluvial deposits carried by three major rivers: the Indus, Ganga, and Brahmaputra, along with their tributaries.

This vast plain is one of the five physiographic divisions of India and stands out as the largest alluvial plain globally. It is the youngest geographical feature of India, characterized by its fertile soil and significant agricultural activity.

Features of the Indo-Gangetic Plains

1. North-South Extension: The Indo-Gangetic Plains stretch from the southern foothills of the Himalayas to the edge of the Peninsular Plateau.
2. East-West Extension: They span from the mouth of the Indus River in the west to the mouth of the Ganga River in the east.
3. Boundaries: Bounded by the Shiwalik range to the north, the desert to the west, the Peninsular Plateau to the south, and the Purvanchal Hills to the east.
4. Length: Total length is 3200 km, with around 2400 km in India and the remainder in Bangladesh.
5. Width: The average width is 150-300 km, widest in the west (up to 500 km) and narrowing to 60-100 km in the east.
6. Area: Occupies around 7.8 lakh sq. km, making it the largest alluvial plain globally.
7. States Covered: Spreads over Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, parts of Jharkhand and West Bengal, and Assam.
8. Extreme Horizontality: With an average elevation of around 200 m and a gradient range of just 15-20 cm.
9. Soil Cover: Rich and fertile soil due to sediment deposition from northern rivers, contributing to agricultural productivity.

Formation of the Indo-Gangetic Plains

These plains owe their formation to the sedimentary activities of three major river systems – the Indus, Ganga, and Brahmaputra. Over time, the sediments carried by these rivers accumulated within the vast depression situated between the Peninsular and Himalayan regions.

During the Tertiary Period, the movement of the Indo-Australian Plate towards the Eurasian Plate initiated the Himalayan formation. This ongoing convergence caused upheavals in the Himalayan region, creating a profound depression, resembling a large syncline, between the Peninsula and the Himalayas. The rivers originating from the Himalayas transported substantial sediment loads, depositing them within this extensive depression. Consequently, the Indo-Gangetic Plains, also known as the Great Plains of India, took shape.

Regional Divisions of the Indo-Gangetic Plains

Regionally, the Indo-Gangetic Plains are categorized into four major divisions:

1. The Rajasthan Plain
2. The Punjab-Haryana Plain
3. The Ganga Plain
4. The Brahmaputra Plain

The Rajasthan Plain

This region forms the western extremities of the Indo-Gangetic Plains, consists the Thar or Great Indian Desert covering western Rajasthan and adjoining areas in Pakistan. The Rajasthan Plain can be divided into two parts:

• Marusthali: The eastern part of the Rajasthan Plain, known as Marusthali, constitutes a proper desert covering a significant portion of the Marwar plain. Despite its appearance as an aggradational plain on the surface, geologically, it is a part of the Peninsular Plateau, as evidenced by vast stretches of sand interspersed with outcrops of bedrock composed of gneisses, schists, and granites. Its eastern section is rocky, while the western part is characterized by shifting sand dunes locally known as Dhrian.
• Rajasthan Bagar: The eastern part of the Thar desert extending up to the Aravalli Range is a semi-arid plain referred to as Rajasthan Bagar. Numerous short seasonal streams originating from the Aravalli drain this area, forming patches of fertile tracts known as Rohi. Streams like the Luni flow southwest of Aravalli and drain into the Rann of Kutch. The region north of the Luni is called Thali or sandy plain. The Thar desert houses several saline lakes such as Sambhar, Didwana, and Khatu.

The Punjab-Haryana Plain

Located to the east and northeast of the Rajasthan Plain, the Punjab-Haryana Plain extends for a length of 640 km in the northwest to southeast direction across the states of Punjab and Haryana. With an average width of 300 km, the plain gently slopes down towards the southwest, causing the rivers in this region to flow in the same direction.

Composed mostly of silts, the soil of this plain is porous. The areas near the river banks, formed by the deposition of new alluvium, are known as Bet. The foot-hill regions of the plain, consisting of large boulders, gravel, sand, and clay, are termed the ‘Bhabar’ Plain, characterized by soil that cannot hold water.

Some notable features of the Punjab-Haryana Plain include:

• Bet Lands: These are fertile floodplains enriched by Khadar sediments deposited annually, making them highly fertile.
• Dhayas: Broad floodplains of Khadar flanked by bluffs.
• Chos: The northern part of the plain, adjacent to the Shiwalik hills, has undergone significant erosion by numerous streams, known as Chhos.

The Ganga Plain

The Ganga Plain is the largest division of the Indo-Gangetic Plains, covering an area of 3.75 lakh sq. km. It is formed by the alluvial deposits of the Ganga River and its tributaries from both the Himalayas and the Peninsular region. Stretching from Delhi to Kolkata across the states of Uttar Pradesh, Bihar, and West Bengal, the plain slopes generally towards the east and southeast.

Geographically, the Ganga Plain is divided into three main sections:

• The Upper Ganga Plain: This forms the westernmost and upper part of the Ganga Plain, bounded by the Shiwalik range to the north, the Peninsular boundary to the south, and the Yamuna River to the west. Its eastern boundary is less defined. Characterized by a very low gradient, rivers flow sluggishly, resulting in the formation of riverine features like bluffs, meanders, oxbow lakes, and sandy stretches.
• Middle Ganga Plain: Located east of the Upper Ganga Plain, it covers the eastern part of Uttar Pradesh and Bihar. Bounded by the Himalayan foothills to the north and the Peninsular edge to the south, its western and eastern boundaries are less distinct. Rivers flow slowly here, creating features such as levees, bluffs, oxbow lakes, and marshes. Floods are common due to the shifting river courses, with the Kosi River being notorious as the ‘Sorrow of Bihar.’
• Lower Ganga Plain: Extending eastward from the Middle Ganga Plain, it encompasses eastern Bihar, Bengal, and most parts of Bangladesh. Bounded by the Darjeeling Himalaya to the north, the Bay of Bengal to the south, the Chotanagpur Highlands to the west, and the Bangladesh border to the east. Notable for its delta formation, around two-thirds of this area comprises the Ganga-Brahmaputra Delta, known for its mangroves and Royal Bengal Tigers.

The Brahmaputra Plain

Located in the northeastern part of India, the Brahmaputra Plain is also referred to as the Brahmaputra Valley, Assam Valley, or Assam Plain. Despite being considered an extension of the Ganga Plain towards the east, it is distinct and separate as a physical unit. Surrounded by the Eastern Himalayas of Arunachal Pradesh to the north, Patkai Bum and Naga Hills to the east, Garo-Khasi-Jaintia and Mikir Hills to the south, and the Indo-Bangladesh border and lower Ganga Plain boundary to the west, it forms a well-defined geographical entity.

Geomorphology of the Indo-Gangetic Plains

Some of the distinctive geomorphological features of the Indo-Gangetic Plains include:

The Bhabar

The Bhabar is a narrow belt, approximately 8-16 km wide, running east-west along the northern boundary of the Great Northern Plains. It extends from the River Indus to the River Tista, running along the foothills of the Shiwaliks. This belt is characterized by alluvial fans, formed by the deposition of unsorted sediments containing gravel and pebbles. Due to the porous nature of the sediments, streams of water often sink underground, resulting in dry river courses except during the rainy season.

The Tarai

The Tarai region lies south of the Bhabhar region and runs parallel to it, with a width ranging from 15-30 km. Streams that flow underground in the Bhabhar region emerge here, resulting in the formation of marshy and damp areas. Composed of finer alluvium, the Tarai is covered by forests. Much of the Tarai area has been converted into agricultural land, particularly in states like Punjab, Uttar Pradesh, and Uttarakhand.

The Khadar

This belt constitutes the floodplain along the riverbanks, where newer alluvium is deposited annually by the rivers, enriching the soil and making it highly fertile. The absence of calcareous deposits in this region further enhances its suitability for extensive cultivation.

The Bhangar (or Bangar)

The “Khadar” refers to the alluvial terrace situated above the floodplain level, constituting the largest part of the Indo-Gangetic Plains. The soil in this area comprises older alluvium and is not regularly replenished, resulting in relatively low fertility. It contains calcareous deposits known as Kankar locally.

Reh or Kallar

The term “Ravines” describes barren areas with salty deposits found in dry regions of Uttar Pradesh and Haryana.

Bhur

These are raised areas of land formed along the banks of the Ganga River due to the accumulation of sand carried by the wind during hot and dry months.

Significance of the Indo-Gangetic Plains

Home to a Large Population: Despite covering less than one-third of the country’s total area, the plains support over 40 percent of the total population.

• Agriculture: The fertile alluvial soils, flat surfaces, slow-moving perennial rivers, and favorable climate make this region ideal for intensive agricultural activity. Consequently, the northern plains are often referred to as the granary of the nation.
• Roads and Railways: The region boasts a well-developed network of roads and railways due to its easy topography. This has led to significant urbanization and industrialization in the area.
• Religious Significance: The presence of numerous religious sites along the banks of sacred rivers like the Ganga and Yamuna adds to the region’s religious significance.

Conclusion – Class 11 Geography Indo-Gangetic Plains

The Indo-Gangetic Plains, also known as the Great Plains of India, are a vital part of India’s landscape. They are home to many people and have fertile soil, which is good for farming. But they face problems like not having enough water and too many people living there. To keep these plains healthy and useful for everyone, we need to make sure we take care of them properly. It is important to use them wisely and protect them for the future.

FAQs on Class 11 Geography Indo-Gangetic Plains

What are the Indo-Gangetic Plains?

The Indo-Gangetic Plains, also known as the Great Plains of India, are a vast and fertile region in northern India formed by the alluvial deposits of the Indus, Ganga, and Brahmaputra rivers.

What states are covered by the Indo-Gangetic Plains?

The Indo-Gangetic Plains span across several states including Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, parts of Jharkhand and West Bengal, and Assam.

What are some distinctive features of the Indo-Gangetic Plains?

Some distinctive features include their fertile alluvial soil, flat terrain, slow-moving rivers, and wide network of roads and railways.

Why are the Indo-Gangetic Plains important?

These plains support a large population, facilitate intense agricultural activity, and hold religious significance due to the presence of sacred rivers like the Ganga and Yamuna.

What are some challenges faced by the Indo-Gangetic Plains?

Challenges include declining fertility, water scarcity, population explosion, and environmental degradation.