1.5 - Geography Notes 36

Elaborate Notes

Mapping

• States with a Single State Border: India has two states, Sikkim and Meghalaya, which share their borders with only one other Indian state.
  • Sikkim: It is bordered by West Bengal to the south. Geopolitically, Sikkim is a crucial state, landlocked by international borders with Nepal to the west, Bhutan to the east, and China’s Tibet Autonomous Region to the north. Its location near the narrow Siliguri Corridor (also known as the “Chicken’s Neck”) underscores its immense strategic importance for India’s connectivity to its northeastern states.
  • Meghalaya: It is surrounded by Assam on its north and east sides. Its southern and western boundaries form an international border with Bangladesh. This geographical disposition makes its economic and social ties with Assam particularly significant.
• Inter-State Border Clarifications:
  • Telangana and Odisha: These two states do not share a common border. Telangana is bordered by Maharashtra and Chhattisgarh to the north, Karnataka to the west, and Andhra Pradesh to the south and east. A sliver of Andhra Pradesh and Chhattisgarh territory separates Telangana from Odisha.
  • Madhya Pradesh and Jharkhand: These states are not contiguous. Madhya Pradesh is centrally located, bordered by Uttar Pradesh, Chhattisgarh, Maharashtra, Gujarat, and Rajasthan. The state of Chhattisgarh lies between Madhya Pradesh and Jharkhand.
• Course of the Yamuna River: The Yamuna River, a major tributary of the Ganga, does not originate in Himachal Pradesh but flows through a portion of it. Its source is the Yamunotri Glacier in the Bandarpoonch massif in the Mussoorie range of the Lower Himalayas in Uttarakhand. After flowing through Uttarakhand, it enters Himachal Pradesh near Paonta Sahib in the Sirmaur district, forming the border with Uttarakhand for a stretch, before flowing south into Haryana, Delhi, and then Uttar Pradesh, where it finally merges with the Ganga at the Triveni Sangam in Prayagraj.

Physiography of India

Subcontinent

A subcontinent is a large, distinguishable part of a continent, such as North America or southern Africa, which, while geographically contiguous with the main landmass, possesses a distinct geographical, geological, and cultural identity.

• Reasons for Considering India as a Subcontinent: The Indian subcontinent is a well-defined peninsular region in South Asia, distinguished from the rest of Asia by formidable physical barriers. The rationale for this classification is multi-faceted:
  • (a) Geographical Reasons: The region has clear, formidable natural boundaries that have historically isolated it. It is bounded by the towering Himalayan and Hindukush-Karakoram ranges to the north, the Purvanchal hills (Arakan Yoma in Myanmar) to the east, and is surrounded by the Indian Ocean, Arabian Sea, and Bay of Bengal to the south, west, and east respectively. This distinct physical enclosure has shaped its history and environment.
  • (b) Geological Reasons: The subcontinent shares a common geological origin. The entire landmass, part of the ancient supercontinent Gondwanaland, broke away and drifted northwards as the Indian Plate. This plate’s collision with the Eurasian Plate, beginning around 50-55 million years ago, led to the formation of the Himalayas and the Tibetan Plateau. This shared tectonic history, as explained by geologists like D.N. Wadia in his work Geology of India (1919), gives the region a unified geological character, evident in its major physiographic divisions.
  • (c) Common Climatic Conditions: The entire subcontinent is dominated by a monsoon type of climate, characterized by seasonal reversal of winds. The Himalayas act as a climatic barrier, preventing cold polar winds from entering the subcontinent and forcing the moisture-laden monsoon winds to precipitate, giving the region its unique climatic rhythm. This was extensively studied by meteorologists like P. K. Das.
  • (d) Political Reasons: In modern geopolitics, the countries of the subcontinent (India, Pakistan, Bangladesh, Nepal, Bhutan, Sri Lanka, Maldives) are collectively referred to as South Asia. They share common platforms like the South Asian Association for Regional Cooperation (SAARC), which fosters a sense of shared political identity and regional cooperation.
  • (e) Historical and Cultural Reasons: The region possesses a deep-rooted, shared civilizational history. It was the cradle of the Indus Valley Civilization (c. 3300–1300 BCE). Over millennia, vast empires such as the Mauryan (c. 322–185 BCE), Gupta (c. 320–550 CE), and Mughal (1526–1857 CE) empires unified large parts of this landmass. This has resulted in a shared cultural tapestry of languages (e.g., the spread of Indo-Aryan languages), religions (birthplace of Hinduism, Buddhism, Jainism, Sikhism), art, architecture, festivals, and social customs, a concept explored by historians like A. L. Basham in The Wonder That Was India (1954).

Mountains of India

Himalayas

• Origin of the Himalayas: The formation of the Himalayas is explained by the theory of Plate Tectonics. The Indian Plate, after separating from Gondwanaland, moved northward and collided with the much larger Eurasian Plate. The sedimentary rocks of the Tethys Sea, which lay between the two plates, were folded, buckled, and uplifted to form the Himalayan mountain ranges. This process of mountain building, known as orogeny, is still ongoing.

• Different Stages in the Formation of the Himalayas: The Himalayan orogeny occurred in three main phases over millions of years:

  • (a) First Stage (Eocene-Oligocene Epoch): Between approximately 65 and 40 million years ago, the initial collision between the plates occurred. This led to intense folding and faulting of the Tethyan sediments, resulting in the uplift of the Great Himalayas (Himadri).
  • (b) Second Stage (Mid-Miocene Epoch): Around 30-25 million years ago, continued compression caused the uplift of the ranges to the south of the Himadri, forming the Lesser or Middle Himalayas (Himachal).
  • (c) Third Stage (Pliocene-Pleistocene Epoch): From about 20 to 2 million years ago, the final phase of uplift occurred. The sediments deposited in the foredeep basin (a depression formed in front of the rising Himalayas) were folded and elevated to create the Shivaliks (Outer Himalayas).

• Syntaxial Bending: This refers to the sharp, hairpin or deep-knee bend in the geological strike of the Himalayan ranges at their western and eastern extremities. This phenomenon was prominently described by the geologist D.N. Wadia (1931).

  • Cause: It is attributed to the northward-drifting Indian Peninsular shield acting as a rigid wedge against the Eurasian Plate. The maximum push was offered at the northwestern and northeastern corners of the peninsula.
  • Mechanism: The Aravalli range in the northwest and the Assam ranges (Karbi-Meghalaya Plateau) in the northeast acted like two rigid protrusions or ‘arms’. The immense compressional force caused the mountain ranges to bend sharply around these points, creating the Nanga Parbat syntaxis in the west and the Namcha Barwa syntaxis in the east.

• Evidence to Prove that the Himalayas are Still Rising:

  • (a) Frequent Earthquakes: The region is one of the most seismically active in the world. The constant movement of the Indian Plate (at about 5 cm per year) against the Eurasian Plate builds up immense stress, which is released in the form of earthquakes, such as the 2015 Nepal earthquake. This indicates ongoing tectonic activity.
  • (b) Recent Adjustments in Height: Modern geodetic surveys using GPS technology have confirmed the uplift. The joint survey by Nepal and China in 2020 revised the height of Mount Everest to 8848.86 meters, which reflects both tectonic uplift and improved measurement techniques.
  • (c) Frequent Topographical Disturbances: The instability of the young mountains is evident in the high frequency of landslides, slope failures, and changes in river courses.
  • (d) Youthful Stage of Himalayan Rivers: Despite flowing for millions of years, the Himalayan rivers exhibit features of a youthful stage, such as deep gorges (e.g., the Indus and Brahmaputra gorges), V-shaped valleys, and a high rate of erosion. This is because their erosional work is constantly being counteracted by the uplift of the landmass.
  • (e) Drying up of Tibetan Lakes: Palaeoclimatological and geological studies of the Tibetan Plateau show that many of its ancient lakes have been drying up. This is partly attributed to the continuous uplift of the plateau, which alters drainage patterns and affects the hydrological cycle.

Regional Division of Himalayas

This classification, based on the river valleys that demarcate the ranges from west to east, was first systematically proposed by geographer Sir Sidney Burrard.

• (a) Kashmir/Punjab Himalayas: Lies between the Indus and Sutlej rivers. It encompasses major ranges like the Karakoram, Ladakh, Zaskar, and Pir Panjal.
• (b) Kumaon Himalayas: Extends between the Sutlej and Kali rivers. Important peaks include Nanda Devi and Kamet. The sources of the Ganga and Yamuna lie in this region.
• (c) Nepal Himalayas: Situated between the Kali and Teesta rivers. This is the tallest section of the Himalayas, containing the world’s highest peaks like Mount Everest, Kanchenjunga, Lhotse, and Makalu.
• (d) Assam Himalayas: Lies between the Teesta and Brahmaputra (Dihang) rivers. It includes peaks like Namcha Barwa. The ranges here are lower in elevation but receive very heavy rainfall.

Feature	Western Himalayas (Punjab & Kumaon)	Eastern Himalayas (Sikkim & Arunachal)
Location	Between River Indus and River Kali.	Between River Teesta and the Brahmaputra.
Width	Wider, due to lesser compressional force.	Narrower and more compressed.
Range Distinction	The three ranges (Great, Middle, Shivalik) are more clearly demarcated.	The ranges are less distinct and appear to have merged in many areas.
Gradient	Rise from the plains is more gradual.	Rise from the plains is abrupt and steep.
Precipitation	Lower precipitation, mainly from Western Disturbances in winter and weaker monsoons.	Higher precipitation, receiving the full force of the Bay of Bengal branch of the monsoon.
Snowline	Lower altitude (around 3500m) due to lower temperatures and less intense summer melting.	Higher altitude (around 4400m) due to higher humidity, cloud cover, and warmer temperatures.
Vegetation	Predominantly coniferous forests (Pine, Deodar, Fir) and alpine meadows.	Rich evergreen and deciduous forests due to high rainfall and temperature.
Biodiversity	Comparatively lower biodiversity.	Extremely high biodiversity; part of the Indo-Burma biodiversity hotspot.

Longitudinal Division

This classification is based on the parallel ranges running from north to south.

• (a) Trans-Himalayas (Tibetan Himalayas): Located to the north of the Great Himalayan range, mostly in Tibet. They include the Karakoram, Ladakh, Zaskar, and Kailash ranges. This region is a cold desert, lying in the rain shadow of the Great Himalayas.
• (b) Great Himalayas (Himadri): The northernmost and highest range, forming a continuous wall extending from Nanga Parbat (8126 m) in the west to Namcha Barwa (7782 m) in the east. It has an average elevation of over 6000 m and contains the world’s highest peaks. Its core is composed of Archaean granites and gneisses.
• (c) Middle/Lesser Himalayas (Himachal): Situated south of the Himadri, these ranges are discontinuous and have an average altitude of 3700-4500 m. They include important ranges like the Pir Panjal Range (longest), Dhauladhar Range, and Mahabharat Range (in Nepal). It is known for its hill stations and scenic valleys like Kashmir and Kangra.
• (d) Shivaliks (Outer Himalayas): The southernmost and youngest range, with an average height of 900-1100 m. They are composed of unconsolidated river sediments (conglomerates) brought down from the higher ranges. They are characterized by longitudinal valleys called ‘Duns’ (e.g., Dehradun, Kotli Dun). The hills in Arunachal Pradesh like Dafla, Miri, Abor, and Mishmi, are eastward extensions of the Shivaliks and Lesser Himalayas, though their geology is complex.
• (e) Purvanchal (Eastern Hills): After the Dihang gorge, the Himalayas take a sharp southward bend and form a series of hills running through the northeastern states. Composed mainly of sandstone, they are known by different local names like the Patkai Bum, Naga Hills, Manipur Hills, and Mizo (Lushai) Hills.

Prelims Pointers

• States sharing a border with only one Indian state: Sikkim (with West Bengal) and Meghalaya (with Assam).
• Sikkim’s international borders are with Nepal, Bhutan, and China.
• Meghalaya’s international border is with Bangladesh.
• Telangana does not share a border with Odisha.
• Madhya Pradesh does not share a border with Jharkhand.
• The Yamuna River flows through Uttarakhand, Himachal Pradesh, Haryana, Delhi, and Uttar Pradesh.
• The Indian Plate is a part of the ancient Gondwanaland supercontinent.
• The Himalayas were formed from the uplift of sediments from the Tethys Sea.
• First phase of Himalayan formation created the Great Himalayas (Himadri).
• Second phase formed the Lesser Himalayas (Himachal).
• Third phase formed the Outer Himalayas (Shivaliks).
• Syntaxial bends are sharp, hairpin bends in the Himalayan ranges.
• The western syntaxis is near Nanga Parbat; the eastern syntaxis is near Namcha Barwa.
• Evidence for the rising Himalayas includes frequent earthquakes, GPS measurements, and youthful river features.
• Revised official height of Mt. Everest (2020) is 8848.86 meters.
• Regional Divisions:
  1. Kashmir Himalayas: Between Indus and Sutlej rivers.
  2. Kumaon Himalayas: Between Sutlej and Kali rivers.
  3. Nepal Himalayas: Between Kali and Teesta rivers.
  4. Assam Himalayas: Between Teesta and Brahmaputra rivers.
• The Western Himalayas are wider than the Eastern Himalayas.
• The snowline is at a higher altitude in the Eastern Himalayas compared to the Western Himalayas.
• Longitudinal Divisions:
  1. Trans-Himalayas: Karakoram, Ladakh, Zaskar, Kailash ranges.
  2. Great Himalayas (Himadri): Extends from Nanga Parbat to Namcha Barwa.
  3. Lesser Himalayas (Himachal): Includes Pir Panjal, Dhauladhar, and Mahabharat ranges.
  4. Shivaliks (Outer Himalayas): Known for longitudinal valleys called ‘Duns’.
  5. Purvanchal: Eastern hills including Patkai Bum, Naga Hills, and Mizo Hills.
• Dafla, Miri, Abor, and Mishmi are hills located in Arunachal Pradesh.

Mains Insights

• Geopolitical Significance of India’s Geography (GS-II):

  • Subcontinent as a Geopolitical Unit: The concept of the Indian subcontinent provides a framework for understanding regional dynamics in South Asia. The shared history and culture can be a basis for cooperation (SAARC), but also a source of conflict arising from the partition and subsequent disputes.
  • Himalayas as a Barrier and a Bridge: While the Himalayas have acted as a formidable defence barrier for centuries, they are also a source of strategic vulnerability (e.g., border disputes with China). They are the source of perennial rivers vital for the subcontinent’s water security, making transboundary water sharing a critical diplomatic issue.
  • Strategic Location: The location of states like Sikkim near the Siliguri Corridor highlights the geographic vulnerabilities that shape India’s defence and foreign policy towards its neighbours.

• Impact of Himalayan Geology on Human Life (GS-I & GS-III):

  • Cause-Effect Relationship: The ongoing tectonic uplift of the Himalayas (cause) makes the entire region highly susceptible to natural disasters like earthquakes, landslides, and flash floods (effect). This poses a significant challenge to infrastructure development and human settlement.
  • Development vs. Environment Debate: The fragility of the Himalayan ecosystem creates a classic development-versus-environment dilemma. Large-scale infrastructure projects (dams, roads) are necessary for economic growth but often exacerbate ecological instability, as seen in events like the 2021 Chamoli disaster. Sustainable development models are crucial for this region.
  • Resource Base: The Himalayas are a repository of vast natural resources, including freshwater (the ‘Water Tower of Asia’), forests, minerals, and immense hydroelectric potential. The management and equitable distribution of these resources are key to the region’s prosperity and stability.

• Cultural and Historical Unity of the Subcontinent (GS-I):

  • Historiographical Viewpoint: Historians view the subcontinent as a distinct civilizational unit where, despite political fragmentation at various times, a continuous thread of cultural exchange and synthesis has existed. The spread of religions, languages, and ideas across the natural barriers (though difficult) created a unique cultural mosaic.
  • Unity in Diversity: The distinct physical geography of the subcontinent has fostered immense regional diversity in language, ethnicity, and customs. However, overarching cultural and historical experiences (e.g., impact of monsoons on agriculture and festivals, influence of ancient empires) have provided a basis for a composite cultural identity. Understanding this dynamic is key to appreciating the social fabric of modern South Asian nations.

• Climate Change and the Himalayas (GS-III):

  • Vulnerability: As the Himalayas are a young and geologically active mountain range, they are extremely sensitive to the impacts of climate change. Accelerated glacier melt not only threatens long-term water security for millions downstream but also increases the risk of Glacial Lake Outburst Floods (GLOFs).
  • Biodiversity Hotspot: The Eastern Himalayas, a global biodiversity hotspot, are under severe threat from climate change, which can alter habitats and lead to species extinction. This has implications for both ecological balance and local livelihoods dependent on biodiversity.