NCERT Summary: The Himalayas | Geography for UPSC CSE PDF Download

The Himalayas, which are relatively young fold mountains, were formed when two tectonic plates collided. They are one of the five major physical divisions of India. In addition to acting as a protective barrier for India’s borders, the Himalayas also separate the Tibetan Plateau in the north from the Indian subcontinent in the south.

Formation of Himalayas

The process of their formation began millions of years ago when the Indian Plate crashed into the Eurasian (Asian) Tectonic Plate. Here’s a detailed look at the key events that led to the formation of the Himalayas:

• Pangea and Panthalassa (250 million years ago): Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras, surrounded by a vast ocean called Panthalassa.
• Breaking of Pangea (150 million years ago): The breakup of Pangea initiated the formation of smaller landmasses, primarily Laurasia in the north and Gondwanaland in the south. Laurasia included present-day North America, Europe, and Asia, while Gondwanaland comprised South America, Africa, South India, Australia, and Antarctica.
• Formation of the Tethys Sea: The fragmentation of Pangea gave rise to the Tethys Sea, a long, narrow body of water located between Laurasia and Gondwanaland.
• Deposition of Sediments: Over time, rivers from both Laurasia and Gondwanaland deposited vast amounts of sediment into the Tethys Sea, gradually filling it up.
• Breaking Down of Gondwanaland and Angaraland: Tectonic activities led to the disintegration of Gondwanaland and Angaraland into smaller land masses. The Indian Plate emerged from Gondwanaland, while the Eurasian Plate formed from Angaraland.
• Convergence of Indian and Eurasian Plates: The Indian Plate, driven by convection currents in the Earth’s mantle, began drifting northwards towards the Eurasian Plate, leading to their eventual convergence across the Tethys Sea.
• Formation of Folds: As the Indian Plate continued its northward journey, the Tethys Sea started to shrink. The sediments on the seabed were pushed upwards, creating folds in the Earth’s crust.
• Genesis of the Himalayas: The Tethys Sea eventually disappeared due to the converging plates and the upward movement of sediments, giving rise to the massive mountain range known as the Himalayas.
• Continued Convergence: The Indian and Eurasian Plates are still converging today, albeit slowly, resulting in the gradual uplift of the Himalayas, which rise approximately 5 millimeters per year.

Longitudinal Division of Himalayas

The Himalayas are divided into three main parts based on their latitudinal extent.

• Trans-Himalayas: This region lies to the north of the main Himalayan range and includes areas such as Ladakh and parts of Arunachal Pradesh.
• The Himalayan Mountain Ranges: This is the central and most prominent part of the Himalayas, featuring the highest peaks, including Mount Everest and Kanchenjunga.
• The Eastern Hills or Purvanchal: This region includes the hills and mountains in the eastern part of the Himalayas, extending into states like Sikkim, West Bengal, Assam, and further into Myanmar.

The Trans-Himalayas

• Trans-Himalayas refer to the mountain ranges located to the north of the Great Himalayan Range.
• These ranges extend approximately 1,000 kilometres from east to west, with an average elevation of around 3,000 metres above sea level.
• Notable ranges within the Trans-Himalayas include the Karakoram Range, Ladakh Range, and Zaskar Range.

Karakoram Range

• The Karakoram Range is the northernmost part of the Trans-Himalayas in India, forming the border between India, Afghanistan, and China.
• This range is approximately 110-130 kilometres wide and is home to some of the world’s highest peaks and largest glaciers, including K2 (Mount Godwin-Austen), the second-highest mountain globally at about 8,611 metres.
• Significant glaciers include the Siachen Glacier and the Remo Glacier.

Ladakh Range

• The Ladakh Range extends southeast from the Karakoram Range, starting at the mouth of the Shyok River in North Kashmir and stretching towards the Indo-Tibetan borders.
• The Deosai Mountains in Pakistan-Occupied Kashmir and the Kailash Range in western Tibet are sometimes considered extensions of the Ladakh Range.

Zaskar Range

• The Zaskar Range runs approximately parallel to the Great Himalayan Range, stretching southeast from the Suru River to the upper Karnali River.
• The highest peak in this range is Kamet Peak, standing at 25,446 feet.

The Himalayan Ranges

• Composition: The Himalayan Range, known as the youngest mountain range in the world, is primarily composed of uplifted sedimentary and metamorphic rocks.
• Boundaries: It is bordered to the northwest by the Karakoram and Hindu Kush ranges, to the north by the Tibetan Plateau, and to the south by the Indo-Gangetic Plains. The southern boundary is distinctly marked by foothills, while the northern boundary seamlessly merges into the Tibetan Plateau.
• Extent: The range spans over 2,400 kilometres, stretching from the Indus Gorge in the west to the Brahmaputra Gorge in the east.
• Width: The range is wider on the western side compared to its eastern counterpart.
• Elevation: The average height of the Greater Himalayas is approximately 6,100 metres. The Western Himalayas exhibit a gradual increase in elevation, while the Eastern Himalayas show a rapid rise in altitude.

Greater Himalayas (Himadri)

• Also referred to as the Inner Himalayas or Central Himalayas, this region is characterised by ancient rocks such as granite, gneisses, and schist.
• The orientation of this area varies: it extends southeast across northern Pakistan, India, and Nepal, curves eastwards across Sikkim and Bhutan, and turns northeast across northern Arunachal Pradesh.
• This region is home to some of the world’s highest peaks, including Nanga Parbat, Mount Everest, Kanchenjunga, and Namcha Barwa.
• The slopes in this area are steep towards the north and more gentle towards the south.

Inner or Middle Himalayas

• Also referred to as the Lesser or Lower Himalayas, this region has an average elevation ranging from 3,500 to 5,000 metres and a typical width of 60 to 80 kilometres. Notable aspects include: 
• Major ranges: Nag Tibba, Mahabharat Range, Dhauladhar, Pir Panjal, and Mussoorie Range. 
• Significant rivers like the Jhelum and Chenab flow through this region. 
• The renowned Valley of Kashmir is situated between the Pir Panjal and Zanskar Ranges. 
• Popular hill stations include Shimla, Chail, Ranikhet, Nainital, and Almora. 
• Formation of Karewas, which are fluvioglacial deposits, is a distinctive feature. 

Shiwalik or Outer Himalayas

This range is the southernmost part of the Himalayas, situated between the Middle Himalayas to the north and the Indo-Gangetic Plains to the south. Key points include:

• The Shiwalik range rises steeply from the Indus and Ganges plains in the south, running parallel to the main Himalayan Range.
• It is separated from the main range by valleys, including the Churia Range in Nepal.
• The formation of Doons and Duars occurred when upliftment halted river flow, creating temporary lakes.
• The sediments deposited in these areas formed fertile alluvial soils, which are crucial for tea cultivation.

The Eastern Hills or the Purvanchal

The Himalayas make a sharp turn to the south near the Dihang Gorge due to the Syntaxial Bend, leading to the Purvanchal region. This region stretches from Arunachal Pradesh in the north to Mizoram in the south and forms part of India’s border with Myanmar.

Prominent Ranges in the Purvanchal Region:

• Patkai Bum: The northernmost range along the boundary between Arunachal Pradesh and Myanmar.
• Naga Hills: Located south of Patkai Bum, these hills form a significant geographical feature near the India-Myanmar border.
• Manipur Hills: Found south of the Naga Hills, separated by the Barail Range.
• Mizo Hills or Lushai Hills: Located to the south of the Manipur Hills, these hills complete the series of hills in the Purvanchal region.

Regional Division of Himalayas

The Himalayas are divided into four regional divisions based on their longitudinal extent:

• Punjab Himalayas: Situated between the Indus River in the west and the Sutlej River in the east, mainly in Jammu and Kashmir and Himachal Pradesh.
• Features prominent ranges like Karakoram, Pir Panjal, Ladakh, Zanskar, and Dhauladhar, characterised by high snow-covered mountains, deep gorges, and mountain passes.
• Kumaon Himalayas: Located between the Satluj River in the west and the Kali River in the east, also known as Garhwal Himalayas in the west. Elevation is higher than the Kashmir Himalayas, home to notable peaks like Nanda Devi, Trisul, Kedarnath, and Kamet.
• Popular hill stations include Nainital, Ranikhet, and Almora.
• Nepal Himalayas: Extends from the Kali River in the west to the Tista River in the east, primarily in Nepal, known for its tallest peaks like Mount Everest, Kanchenjunga, and Dhaulagiri. The Kathmandu Valley is a prominent feature of this region.
• Assam Himalayas: Stretches from the Tista River in the west to the Brahmaputra River in the east, covering Assam and Arunachal Pradesh. Lower in elevation than the Nepal Himalayas, with ranges arranged in a north-south direction due to a sudden southward turn in Arunachal Pradesh.
• Notable peaks include Namcha Barwa, Gyala Peri, Kengto, and Nyegyi Kangsang.

Syntaxial Bends of Himalayas

• Western Syntaxial Bend: Located near Nanga Parbat, where the Indus River carves a deep gorge. This bend marks the end of the east-west trend of the Himalayan Ranges.
• Eastern Syntaxial Bend: Situated near Namcha Barwa in Arunachal Pradesh, where the Himalayan ranges turn south after crossing the Brahmaputra River. This bend signifies the eastern end of the Himalayas.

Significance of the Himalayas

• Climatic Influence: The Himalayas play a crucial role in shaping India’s climate by blocking monsoonal winds and regulating rainfall patterns.
• Security: Acting as a natural defence barrier, the Himalayas provide security for the northern borders of India.
• Perennial Source of Water: The region is the source of major rivers that are vital for North India, ensuring a continuous supply of freshwater.
• Forest Wealth: The Himalayas are rich in biodiversity, offering various raw materials such as timber, medicinal plants, and non-timber forest products crucial for industries.
• Agriculture: The terraced slopes of the Himalayas are suitable for cultivation, supporting various agricultural activities.
• Minerals: The region is abundant in valuable minerals, contributing to both local and national economies.
• Hydroelectricity: There is significant potential for generating hydroelectric power from the fast-flowing rivers and the rugged terrain of the Himalayas, providing a renewable source of energy.