Most Important Long Question (Class 11 Geography: Physiography)

 

Question: Describe the formation and major longitudinal divisions of the Himalayan mountain range. Explain its overall significance for the Indian subcontinent.

 

Answer:

 

The Himalayan Mountains represent the youngest, loftiest, and most rugged mountain barriers in the world. Stretching over an arc of about 2,400 km from the Indus gorge in the west to the Brahmaputra gorge in the east, they form the northern boundary of the Indian subcontinent.

 

Formation of the Himalayas:

 

The Himalayas are classic examples of young fold mountains, formed due to the immense tectonic forces resulting from the collision of two large continental plates:

 

The Indian Plate: Which was drifting northward.

 

The Eurasian Plate: A larger, relatively stable plate.

 

Millions of years ago, a large geosyncline (a long, narrow, shallow sea) called the Tethys Sea existed between these two plates. The Tethys Sea was continuously accumulating sediments from the peninsular rivers to the south and Eurasian rivers to the north. Around 50-60 million years ago, the northward movement of the Indian Plate led to its collision with the Eurasian Plate.

 

Since the continental crusts are buoyant and cannot easily subduct, the immense compressive forces generated by this collision caused the accumulated sediments of the Tethys Sea to be folded, uplifted, and intensely compressed. This gradual, ongoing process of folding and upliftment over millions of years led to the formation of the successive parallel ranges of the Himalayas. The process continues even today, making the Himalayas tectonically active and prone to earthquakes.

 

Major Longitudinal Divisions of the Himalayas:

 

The Himalayas are not a single mountain range but consist of three prominent parallel ranges, running almost continuously from west to east:

 

The Greater Himalayas (Himadri):

 

Location: The northernmost and most continuous range.

 

Characteristics: It is the highest range with an average elevation of over 6,000 meters. It contains the world's loftiest peaks, including Mount Everest (Nepal), Kanchenjunga (India), Nanga Parbat, Annapurna, and Dhaulagiri. The Himadri is perpetually snow-bound and houses numerous glaciers, which are the source of major perennial rivers like the Ganga and Yamuna. It is composed primarily of highly resistant crystalline and metamorphic rocks.

 

The Lesser Himalayas (Himachal):

 

Location: Lies to the south of the Himadri, running parallel to it.

 

Characteristics: This range has an average altitude varying from 3,700 to 4,500 meters. It is composed of highly compressed and altered rocks. Famous for its beautiful valleys (e.g., Kashmir Valley, Kangra Valley, Kullu Valley) and popular hill stations like Shimla, Kullu, Manali, Mussoorie, Nainital, and Darjeeling. Prominent ranges include the Pir Panjal (the longest range), Dhaula Dhar, and Mahabharat Lekh.

 

The Shiwaliks (Outer Himalayas):

 

Location: The southernmost and youngest range of the Himalayas, lying parallel to the Lesser Himalayas.

 

Characteristics: With an average altitude varying from 900 to 1,100 meters, these ranges are primarily composed of unconsolidated sediments (gravel and alluvium) brought down by rivers from the higher Himalayan ranges. The valleys between the Lesser Himalayas and the Shiwaliks are known as 'Duns' (e.g., Dehra Dun, Kotli Dun, Patli Dun), which are flat-bottomed, fertile longitudinal valleys.

 

Overall Significance of the Himalayas for the Indian Subcontinent:

 

The Himalayas play an immensely vital role in shaping the geography, climate, economy, and culture of the Indian subcontinent:

 

Climatic Barrier: They act as a formidable climatic barrier. They intercept the moisture-laden Southwest Monsoon winds originating from the Arabian Sea and Bay of Bengal, forcing them to shed their moisture as rain over the Indian subcontinent. Conversely, they prevent the cold, dry winds from Central Asia from entering India, keeping the northern plains warm in winter.

 

Source of Perennial Rivers: The Himalayas are the source of major perennial rivers like the Indus, Ganga, and Brahmaputra, along with their numerous tributaries. These rivers ensure a continuous supply of water for agriculture, drinking, and industrial purposes throughout the year, sustaining life in the vast Northern Plains.

 

Formation of Fertile Northern Plains: The mighty rivers originating from the Himalayas deposit vast amounts of rich alluvial sediments, leading to the formation of the highly fertile Northern Plains. These plains are the "granary of India," supporting intensive agriculture and a large population.

 

Forest Wealth and Biodiversity: The varying altitudes and climates of the Himalayas support a rich diversity of natural vegetation, ranging from tropical deciduous at lower levels to coniferous and alpine forests at higher altitudes. These forests provide valuable timber, medicinal plants, and are home to a unique array of flora and fauna, making the region a biodiversity hotspot.

 

Hydroelectric Power Potential: The numerous perennial rivers flowing through the steep Himalayan slopes offer immense potential for hydroelectric power generation, which is crucial for India's energy security and industrial development.

 

Defense: Historically, the Himalayas have provided a natural and formidable northern frontier, protecting India from invasions from Central Asia.

 

Tourism and Pilgrimage: The scenic beauty, challenging terrain, numerous hill stations (e.g., Shimla, Manali, Nainital), and sacred pilgrimage sites (e.g., Badrinath, Kedarnath, Amarnath) attract millions of tourists and pilgrims, contributing significantly to the regional economy.

 

In conclusion, the Himalayas are not merely a mountain range but a life-sustaining system that profoundly influences every aspect of the Indian subcontinent, from its climate and agriculture to its cultural identity and strategic importance.