PHYSIOGRAPHY OF INDIA

PHYSIOGRAPHY OF INDIA

The land of India is characterized by great diversity in its physical features. The north has a vast expanse of rugged topography consisting of a series of mountain ranges with varied peaks, beautiful valleys, and deep gorges. The south consists of stable tableland with highly dissected plateaus, denuded rocks, and developed series of scarps. The reasons for variation in the topography could be:

• Differences in the rock formations: These landmasses have been formed in different geological periods.
• Number of processes: Such as weathering, erosion, and deposition has modified these features to their present forms.

India is a country of physical diversity. There are high mountain peaks in some areas, while in others lie the flat plains formed by rivers. On the basis of physical features, India can be divided into the following divisions:

• Hindu Kush-Karakoram-Himalayas Region
• The Great Plains of north India
• The Peninsular Plateau
• The Coastal Plains
• The Islands
  

HINDU KUSH-HIMALAYAS REGION

Length: This mountain region of 2500 km is spread uninterruptedly from Jammu and Kashmir in the west to Arunachal Pradesh in the East.

Highest peak in East: It is wider in the West (500 km) than in the East (200 km).

• Reason: The compression force was more in the east than in the West during the formation of the Himalayas. This is why high mountain peaks like Mount Everest and Kanchenjunga are present in the Eastern Himalayas.

ORIGIN OF HIMALAYAS

The origin can be understood in 5 stages:

Stage 1

Collision of plates: Himalayas are the outcome of the collision between the Indian plate and Eurasian plate. During the Cretaceous period, the Indian peninsula broke away from Gondwana and started its northward journey. The Tethys present between the two plates got squeezed, forming a geosyncline.

Volcanism: As the plate moved northwards, the oceanic margin of the Indian plate got subducted, leading to volcanism, and part of these rocks is preserved in the Ladakh region.

Stage 2

Formation of Potwar Plateau: Around 60 million years ago, the northwestern part of the Indian plate hit the Eurasian plate, leading to the formation of the Potwar Plateau. Then the plate took an anti-clockwise turn, leading to the creation of the Eastern Himalayas.

Stage 3

Formation of Tethian Himalayas: Further northward movement and compression of the Tethys sea led to the rising of Tethian Himalayas.

Stage 4

Formation of Main Himalayas: Continuous convergence of mountains leads to formations of fold mountains called Main Himalayas or Greater Himalayas, and south of it, the Main Central Thrust was created.

Formation of Lesser and Middle Himalayas: As the process continued, another fold mountain emerged, Lesser Himalayas or Middle Himalayas, and south of it, the Main Boundary Fault line was created.

Stage 5

Formation of Shivalik Mountains: With the formation of Greater and Lesser Himalayas, foredeep was created at the foothill of these mountains, where deposition and further compression led to the formation of Shivalik mountains. A new fault line emerged south of it, called the Himalayan Frontal Fault.

Himalayas are still rising The Indian Plate is still moving northwards at a rate of 5 cm per year and pushing into the rest of Asia, thereby constantly increasing the height of the Himalayas. Thus, the process of mountain building is ongoing, and the Himalayan region frequently experiences earthquakes.

Evidence that Himalayas are still Rising

• Fossils found in Tibet: Fossils found in Shivalik Hills are also found in the Tibet plateau, indicating that the past climate of the Tibet plateau is similar to Shivalik.
• Occurrence of earthquakes: Frequent earthquakes in the Himalayan belt show that the Himalayas have not yet attained isostatic equilibrium.
• Youthfulness of rivers: Himalayan rivers are still in their youthful stage.

DIVISION OF HIMALAYAS

Based on relief, alignment of ranges, and other geomorphological features, the northern mountain region can be divided into three parts:

1. The Himalayan Mountains
   • Location: Himalayas lie to the north of the Ganga-Brahmaputra Plains and are separated from the plains by the Himalayan Front Fault.
   • Young fold mountain: Himalayas are the young fold mountains, the highest mountain range in the world.
   • Length and width: They run from west to east from the Indus to Brahmaputra, covering 2500 km. Width varies from 400 km in the west to 150 km in the east.
   • The Greater Himalayas or Himadari
     • Location: It rises abruptly like a wall north of the Lesser Himalaya, separated by the Main Central Thrust.
     • Width and height: About 25 km wide with an average height above 6100 m.
     • Features: It is the most continuous range. It is snowbound, and many glaciers descend from this range. Peaks like Mt. Everest, Kanchenjunga, and Nanga Parbat are here. Composed of crystalline, igneous, or metamorphic rocks.
   • Lesser Himalayas or Himachal
     • Location: Lies south of the Main Central Thrust.
     • Width and height: Altitude between 1000 and 4500 meters; average width is 50 km.
     • Features: Prominent ranges include Pir Panjal, Dhaula Dhar, and Mahabharata. Composed of un-fossiliferous sediments or metamorphosed crystalline rocks like slate, limestone, and quartzite.
   • Outer Himalayas or the Shivaliks
     • Location: Extends from Jammu division of Jammu and Kashmir to Assam.
     • Width and height: Altitude varies between 900-1100 meters; width between 10-50 km.
     • Features: Broad in the west, narrows down in the east. Contains Doon valleys; mainly composed of sandstones and clay rocks.
2. The Trans-Himalayas
   • Location: Extends north of the Greater Himalaya, called the Zaskar Range.
   • Rock Structure: Contains Tethys sediments, marine fossils, and is partly metamorphosed.
3. The Purvanchal hills
   • Location: The Brahmaputra marks the eastern border of the Himalayas. Beyond the Dihang gorge, the Himalayas bend sharply, forming the Eastern hills or Purvanchal.
   • Features: Includes Mishami, Patkoi, Naga, and Mizo hills located in eastern India. The Meghalaya plateau includes hills like Garo, Khasi, and Jaintia.

Longitudinal Division of the Himalayas

• Punjab Himalayas: 560 km stretch between the Indus and Sutlej, includes Ladakh, Pir Panjal, and Bhaskar ranges.
• Kumaon Himalayas: Extends from Sutlej to Kali River; has 360 lakes.
• Nepal Himalayas: From Khali to Teesta, includes peaks like Mount Everest.
• Assam Himalayas: From Teesta to Brahmaputra, with steep southern slopes.

Significance of Himalayas

• Physical barrier: Acts as a natural barrier to neighbors.
• Climatic influence: Affects monsoon winds and precipitation.
• Defense: Prevents invasions from the north.
• Source of rivers: Many rivers originate from the Himalayas.
• Source of fertile soil: Alluvial soil deposits in the Great Plains.
• Provide temperate climates: Supports crops like barley, maize, and potatoes.
• Hydroelectric generation: Rivers used for hydropower.
• Minerals: Rich in petroleum, limestone, and precious stones.

• Forest Wealth: There is horizontal zonation of vegetation in the Himalayas. The natural vegetation in the Himalayas varies from the humid tropical to the conifers and alpine pastures. At the higher altitudes are the alpine pastures (margs) used by the tribals for grazing cattle during the summer season.
• Tourism: Himalayas are a favored place for nature, leisure, and religious pilgrimage.
• Biodiversity: The Himalayas are one of the biodiversity hotspots of the world. They are home to a rich variety of flora and fauna, including medicinal herbs.

Causes of Melting Glaciers

• CO2 Emissions: The atmospheric concentration of carbon dioxide and other greenhouse gases (GHGs) produced by industry, transport, deforestation, and burning fossil fuels warms the planet and causes glaciers to melt.
• Oil and Gas Drilling: The oil and gas extraction processes also emit methane, a main component of natural gas, which is more damaging to the environment than carbon dioxide, locking in heat more effectively and escalating global warming.
• Deforestation: Trees play a critical role in balancing the ecosystem and cooling the planet. Cutting down trees for human activities disrupts this balance.

Impact of Melting Ice

1. Geographical/Ecological
   • Energy Security: Many regions depend on water from melting glaciers for electricity. Reducing or stopping this flow can halt electricity production.
   • Changes in the Monsoon: In Asia, monsoons support millions of people. Global warming alters these patterns, increasing flood risks.
   • Flooding: Melting glaciers add water to rivers, lakes, and seas, causing sudden rises.
   • Loss of Biodiversity: Glaciers sustain many species. Some animals, like the snow leopard, require cold environments.
   • Agricultural Yields: Reduced glacier water impacts land fertility, affecting crop production.
   • Shortage of Freshwater: Population growth and glacier loss will cause freshwater scarcity.
   • Increased Global Warming: Glaciers reflect heat; as they melt, global temperatures increase.
2. Social
   • Flooding of Cities: Himalayan riverbank cities face flood risks, leading to humanitarian crises.
   • Disease: Melting ice may release long-frozen pathogens.
   • Lack of Freshwater: Glacier melt impacts freshwater availability, causing drought risks.
   • Disasters: Melting ice increases risks of avalanches, floods, and landslides.

THE GREAT PLAINS

• Location: Stretching east-west between the Himalayas and Peninsular Plateaus.
• Stretch: The plains extend for 3,200 kilometers from the Ganga to the Indus, with a width of 150-500 km, covering over seven lakh square kilometers.
• Formation: Formed primarily by rivers—the Indus, Ganga, and Brahmaputra—these plains constitute one of the largest aggregation surfaces globally.

Origin of the Great Plains There is no consensus among geologists on the origin of the Great Plains of India. Some theories are:

• Alluviation of the Foredeep: Formed in front of Himalayan crust waves, checked by the Indian peninsula.
• Infilling of a Rift Valley: Believed that a rift valley filled between two parallel faults.
• Recession of the Sea: A sea extended from east to west during the Eocene, gradually receding with Himalayan river deposits.
• Remnants of the Tethys: Rivers from the Himalayas deposited sediment in the Tethys trough, forming the plains.
• Recent Views: Northern Plains represent a crust sag due to the northward drift of the Indian subcontinent and Tethyan sediment accumulation.

Physiographic Division of the Great Plains of India Based on alluvium characteristics, surface gradient, drainage, and regional traits, the Great Plains are divided into:

• Himalaya
• Bhabar
• Terai
• Bhangar
• Khaddar
  

• Bhabar Plains: Lies along the foot of the Shiwaliks from the Indus to the Tista. It is a narrow belt, 8 to 16 km wide, comprising pebble-studded rocks in the shape of porous beds. These beds are laid down by streams from the mountains. Due to high porosity, all streams disappear here, making the region unsuitable for cultivation. It is characterized by big trees with large roots.
• Terai Plains: Situated to the south of the Bhabar and running parallel to it. It is marked by the re-emergence of underground streams. The alluvium here is finer than in the Bhabar and supports dense forests and wildlife. It is ideal for the cultivation of wheat, rice, maize, and sugarcane.
• Bhangar Plains: Located further south of Terai, formed by deposition of older alluvium or silt by rivers. It contains calcium carbonate nodules called “kankars.”
• Khadar Plains: Comprising newer alluvium deposited by river floods each year, known for fertile soil supporting crops like rice, wheat, maize, and sugarcane.
• Delta Plains: An extension of the Khadar plain, covering 1.86 lakh km² in the lower reaches of the Ganga, mainly marshy, and suitable for paddy, tea, and jute cultivation.

Division of Indo-Gangetic and Brahmaputra Plains

1. Sindh Plains
   • Bhangar Plains: Composed of older alluvium deposited by the Indus and its tributaries.
   • Features: Includes narrow depressions called Dhors and alkaline lakes known as Dhands.
2. Rajasthan Plains
   • Desert Dominance: Occupied by the Thar Desert (Marusthali).
   • Features: Includes undulating plains with peninsular geological formations and aggradational plains.
   • Land Profile: Marusthali (eastern rocky region) and Rajasthan Bagar (fertile semi-arid plain with short streams).
3. Punjab Plains
   • Formed by sediments deposited by the Indus tributaries (Jhelum, Chenab, Sutlej, Beas, and Ravi).
   • Features: Includes Doabs (areas between rivers) and the Malwa Plain to the south of Sutlej.
4. Ganga Plains
   • Largest section of the Northern Plains, covering 3.75 lakh sq. km.
   • Features: Sediment-rich area, gently slopes southeast, forming landforms like oxbow lakes and marshes. Divided into Rohilkhand, Awadh, Mithila, and Magadh plains.
5. Brahmaputra Plains
   • Primarily in Assam, bordered by Purvanchal hills in the east and Gangetic plains in the west.
   • Features: Characterized by depositional plains with oxbow lakes and marshy Terai conditions.

Significance of Great Plains

• Heavy concentration of population: Hosts half of India’s population on one-fourth of its land.
• Agricultural land: Fertile alluvial soils, flat surface, slow-moving perennial rivers, and favorable climate promote agriculture.
• Granary of India: Extensive irrigation supports Punjab, Haryana, and parts of Uttar Pradesh as granaries.
• Industrialization and urbanization: Well-connected by roads and railways, except the Thar Desert, aiding large-scale industrialization.
• Cultural tourism: Religious sites along sacred rivers like the Ganga and Yamuna. Origin of religions such as Buddhism, Jainism, and Bhakti movements.
• Minerals: Plains hold petroleum and natural gas deposits.
• Cradle of Civilization: Birthplace of ancient civilizations like Harappa and Mohenjodaro.

PENINSULAR PLATEAU

The Peninsular Plateau is a triangular tableland, part of the ancient Gondwana landmass. It spans nearly 5 lakh sq. km across Gujarat, Maharashtra, Bihar, Karnataka, and Andhra Pradesh.

Features

• Oldest landform: One of Earth’s oldest landforms.
• Archaean gneisses: Composed of stable Archaean gneisses and schists.
• Stable shield: Limited structural change over time.
• Aggregation of small plateaus: Includes several smaller plateaus and hill ranges.

Division of Peninsular Plateau

1. Central Highlands: Bounded by the Narmada, Aravalis, and Satpura range. Includes Malwa and Chhotanagpur Plateaus.
2. Deccan Plateau: Separated by a fault from Chhota Nagpur Plateau. Known for its black soil, suitable for cotton and sugarcane, with Western and Eastern Ghats.
3. Northeastern Plateau: Extension of the main plateau, includes Meghalaya and Karbi Anglong plateaus.

Significance of Peninsular Plateau

• Mineral deposits: Rich in metallic (e.g., iron) and non-metallic minerals (e.g., bauxite).
• Fertile black soil: Suitable for cotton and citrus cultivation.
• Soil diversity: Supports varied rural economies, particularly on the Dharwar and Vindhyan formations.
• Forest economy: Western Ghats and Nilgiris support dense forests for the economy.
• Hydroelectricity: Rivers create gorges and rapids used for hydroelectricity.
• Tourism: Attractions like Panchmarhi and Ooty.
• Forest products: Rich in medicinal plants and wildlife.
• Tribal home: Inhabited by many tribal communities, primarily Dravidian cultures south of the Vindhyan range.

THE COASTAL PLAINS

The coastal plains flank the Peninsular Plateau, divided into:

1. Gujarat Coastal Plains: Excludes Banaskantha and Sabarkantha, formed by winds and sea recession.
2. Western Coastal Plain: Lies between the Sahyadri and the Arabian Sea, with sandy beaches, dunes, mudflats, and estuaries.
3. Eastern Coastal Plain: Characterized by extensive deltas and broken by numerous hills.

Comparison of the Western Coastal Plains and Eastern Coastal Plains

Significance of the Indian Coastal Plains

• Farming: Fertile soils support rice and coconut cultivation.
• Minerals: Rich in mineral oil and monazite (used for nuclear power).
• Salt production: Gujarat produces salt.
• Equable climate: Ideal for human settlement with minimal temperature extremes.
• Domination: Provides extensive reach into the Indian Ocean.
• Trade: Long coastline with ports aids oceanic trade.
• Marine Economy: Access to resources in the Exclusive Economic Zone.
• Tourism: Mangroves, coral reefs, and estuaries attract tourism.
• Fishing: Supports fishing communities.
• Wind Energy: Potential for onshore wind farms.
• Strategic Advantage: Acts as a gateway to landlocked countries like Nepal and Bhutan.

THE ISLANDS

India has 615 islands; 572 in the Bay of Bengal and 43 in the Arabian Sea. Notable islands include coral islands in the Gulf of Mannar and Khambat, and islands near the mouth of the Ganga river.

Indian Island Groups

1. Andaman and Nicobar Islands
   • Location: Situated in the Bay of Bengal, extending from 6°39′ N to 14°34′ N.
   • Origin:
     • Collision of Plates: Formed from the collision between Indian and Burma Minor Plates.
     • Tectonic Nature: Volcanic and tectonic.
     • Extension: Southward extension of the Arakan Yoma range.
   • Climate: Tropical marine, influenced by monsoon winds.
   • Abode of Tribes: Home to tribes like the Onges, Jarawas, and Sentinelese, facing threats to their way of life.
2. Lakshadweep Islands
   • Location: Situated in the Arabian Sea, comprising 36 islands.
   • Largest Island: Minicoy.
   • Origin: Coral islands, part of the Reunion Hotspot volcanism.

Issues Faced by the Islands

1. Environmental:

• Deforestation: Due to development.
• Sea Level Rise: Causing erosion and submersion.
• Ecological Fragility: Commercial exploitation threatens fragile ecosystems.
• Coral Reefs: Affected by pollution and urbanization.
• Disaster Management: Prone to cyclones and tsunamis.
• Threatened Species: Includes endangered species like the Nicobar shrew and unique reptilian species.

2. Social:

• Education: Limited facilities compel students to study on the mainland.
• Rising Crime: Issues with smuggling and illegal activities.
• Healthcare: Limited healthcare facilities beyond primary care; tertiary or advanced medical care centers are almost non-existent. Tribal Fragmentation: Tribal groups are diminishing due to land fragmentation or loss of indigenous culture.

3. Economic

• Revenue Sources: Untapped sources like fisheries and sustainable tourism.
• Job Prospects: Limited employment in islands, especially in Lakshadweep, which relies mostly on fisheries.
• Poor Connectivity: Limited transport via freighters and air cargo.
• Poor Ports: Most ports serve local needs and function as ports of call.

Way Forward

• Ecosensitive Zones: Declare certain areas as ecosensitive to protect them from development.
• Tribal Protection: Protect tribal communities from harassment, especially in the Andamans.
• Native Rights: Prioritize rights of local populations over commercial interests.
• Organic Farming: Promote organic farming for sustainable employment for locals and tribal communities.
• Social Infrastructure: Improve healthcare and education with community support.