Division of the Himalayas: Shiwaliks, Lesser Himalayas, Greater Himalayas, Trans-Himalayas, Eastern Hills Overview

The Himalayan mountain system is not a single, monolithic range but a stunning tapestry of parallel mountain belts, each boasting unique geological, climatic, and ecological characteristics. This detailed geographical division is essential for understanding the Indian subcontinent's physical features, climate patterns, and ecological biodiversity, serving as crucial knowledge for students preparing for UPSC and other geography examinations. This structure helps map the evolution from the youngest Shiwaliks to the ancient Trans-Himalayas.

The Comprehensive Geographical Division of the Himalayas: Parallel Ranges, Formation, and Unique Ecology

• The majestic Himalayas are systematically divided into four major parallel belts and the eastern extensions, a classification crucial for deciphering their complex formation and varied landscapes.

  The vast expanse of the Himalayan ranges, often called the "Abode of Snow," is geographically segregated into distinct divisions that run parallel to each other from west to east. This systematic division, based on elevation and geological age, helps geographers and students alike to better understand their formation mechanisms, their influence on the Indian climate, and their rich ecological significance.

  • (i) This essential division helps in the detailed analysis of the mountains' formation (tectonic processes) and their consequent climate and ecological differentiation.
  • (ii) The ranges progress from the youngest, outer ranges (Shiwaliks) to the oldest, innermost core (Greater Himalayas and Trans-Himalayas).



• 1. The Shiwaliks or Outer Himalayas: The Youngest and Southernmost Range

  The Shiwaliks, representing the frontier of the Himalayan system towards the plains, are the most recent and lowest range, characterized by unconsolidated sedimentary deposits.

  • Extent, Elevation, and Unique Topographical Features of the Shiwaliks

    This range forms the foothills, acting as a buffer between the towering Lesser Himalayas and the vast alluvial plains of India. Their geological youth is reflected in their fragmented and dissected structure, which is vital for understanding river patterns.

    • (i) Description and Location: Also known as the Outer Himalayas, they are the youngest range and lie strategically between the Great Plains of India and the Lesser Himalayas.
    • (ii) Elevation and Extent: Their elevation is relatively low, ranging from 600 to 1500 meters above sea level. They stretch for approximately 2,400 km, extending from the Potwar Plateau in Pakistan to the Brahmaputra valley in Assam.

      

    • (iii) Topographical Structure: The hills are characterized by a steep southern slope facing the plains and a gentler northern slope. The structure is part of folded mountains where valleys are part of synclines and hills are part of anticlines or antisynclines.

      

      The range exhibits narrowing, from about 50 km in Himachal Pradesh to less than 15 km in Arunachal Pradesh.

  • Geological Composition, Duns Formations, Flora, and Regional Names

    The distinctive features of the Shiwaliks include their composition of river-deposited materials and the creation of longitudinal valleys known locally as 'duns' or 'doons'.

    • (a) Geological Composition: The range is primarily formed by conglomerates of sand, stone, silt, and gravel, remnants deposited by rivers flowing from the higher Himalayas.
    • (b) Duns Formation: These conglomerates initially obstructed river courses, leading to the formation of temporary lakes. When these lakes drained, they left behind flat, fertile longitudinal valleys, famously known as duns, with Dehra Dun in Uttarakhand being the most notable example.
    • (c) Flora and Fauna: The eastern parts tend to be densely forested, supporting rich biodiversity. However, moving west, forest cover diminishes. The southern slopes in Punjab and Himachal Pradesh are characterized by seasonal streams called Chos, which heavily dissect and erode the land.
    • (d) Regional Names: The Shiwaliks carry different local names across their extent, highlighting regional cultural ties: they are the Jammu Hills locally; include the Dafla, Miri, Abor, and Mishmi Hills in Arunachal Pradesh; and feature the Dhang Range and Dundwa Range in Uttarakhand, and the Churia Ghat Hills in Nepal.

• 2. Lesser or Middle Himalayas (Himachal): The Home of Famous Hill Stations

  The Lesser Himalayas, or Himachal, represent the middle belt of the system, known for their complex relief and geological structure, and are particularly famous for their hospitable climate and stunning valleys.

  • Elevation, Topographical Contrast, and Significance for Tourism

    Lying between the youthful Shiwaliks and the towering Greater Himalayas, this range exhibits a significant rise in elevation and hosts some of the most popular resorts in the Indian subcontinent.

    • (i) Location and Elevation: Also called the Himachal or Lower Himalayas, this range runs parallel to the other two major belts. The elevation varies significantly between 3,500 to 4,500 meters, with several peaks soaring above 5,050 meters.
    • (ii) Topographical Contrast: The southern slopes are characteristically steep and barren, making soil development challenging. Conversely, the northern slopes are more gradual and are typically covered by dense forests.
    • (iii) Significance and Resorts: This region's importance is underscored by its hospitable climate, making it a highly popular destination for hill stations and resorts, including Shimla, Mussoorie, Ranikhet, and Darjeeling.

  • Major Ranges within the Lesser Himalayas: Pir Panjal and Dhaola Dhar

    The Lesser Himalayas are composed of several distinct and prominent ranges, with the Pir Panjal being the most extensive and strategically important.

    • (a) Panjal Range: This is the longest and most significant range, primarily located in Kashmir, extending for over 300 km from the Jhelum River to the Beas River. It is crucial due to key passes like Pir Panjal Pass, Bidil, Golabghar Pass, and Banihal Pass, which serve as vital connectivity points.

      

    • (b) la Dhar Range: Located further south of the Pir Panjal, this prominent range is situated entirely within Himachal Pradesh.
    • (c) r Ranges: This belt also includes the Mussoorie Range, which continues eastward into the Mahabharat Lekh in southern Nepal, and the high-elevation Nag Tibba Range.

• 3. The Greater Himalayas (Himadri): The Core of the Highest Peaks

  The Greater Himalayas, also known as the Inner Himalayas or Himadri, form the highest, most continuous, and most heavily glaciated range, representing the core axis of the entire Himalayan system.

  • Geology, Topography, and Hosting the World's Tallest Peaks

    This range is characterized by profound geological complexity and towering, snow-clad peaks, which have defined global mountaineering and geographical studies.

    • (i) Core Structure and Elevation: This is the core range, with a high average elevation of 6,100 meters above sea level and a relatively narrow width of about 25 km.
    • (ii) Geology and Folds: It is primarily composed of central crystallines, including hard metamorphic rocks like granites and gneisses, often overlaid by metamorphosed sediments such as limestone. The folds are characteristically asymmetrical, with a steep southern slope and a gentle northern slope, creating a distinctive hogback topography.
    • (iii) Global Significance: The Himadri is globally significant for housing the tallest peaks in the world, including Mount Everest (known as Sagarmatha in Nepal and Chomlungma in China), which stands majestically at 8,848 meters.

  • Important Passes and Connectivity across the Greater Himalayas

    Despite their extreme height, this range is pierced by numerous high-altitude passes that are historically crucial for trade and connectivity between the Indian subcontinent and Tibet.

    • (i) Burzil Pass: Located in Jammu and Kashmir, a critical route.
    • (ii) Zoji La: Essential for connecting Srinagar to Ladakh.
    • (iii) Bara Lacha La: Provides a vital link between Himachal Pradesh to Leh.
    • (iv) Lipu Lekh: A historic pass that links the Kumaon region to Tibet.
    • (v) Nathu La: A significant trade route connecting Sikkim to Tibet (China).

• 4. The Trans-Himalayas – Tibetan Himalayas: The Northernmost Ranges

  The Trans-Himalayas, largely situated in Tibet, lie immediately north of the Great Himalayas and are characterized by a rugged, arid, and high-altitude landscape.

  • Major Ranges, Elevation, and Geographical Features

    This complex system encompasses some of the highest and most remote peaks and ranges, forming the northern geographical boundary of the Indian subcontinent.

    • (i) Key Ranges Included: The system incorporates important ranges such as Zaskar, Ladakh, Kailas, and Karakoram.
    • (ii) Elevation and Extent: They possess an average elevation of 3,000 meters above sea level and stretch for approximately 1,000 km from east to west.
    • (iii) World Significance: The region is known for featuring some of the world's highest peaks and largest glaciers outside of the polar regions, testifying to its extreme environment.

  • Notable Peaks and the Source of Major Rivers

    The Trans-Himalayas are the location of key geographical features, including Nanga Parbat and K2, and serve as the source region for major rivers.

    • (a) ar Range: Includes the magnificent Nanga Parbat (8,126 meters).
    • (b) as Range: Features the sacred Mount Kailas (6,714 meters), which is the geologically important source of the River Indus.
    • (c) koram Range: Extending about 800 km, this range hosts some of the world's highest peaks, most notably K2 (Mount Godwin Austen) at 8,611 meters, the second-highest peak globally.

• 5. The Eastern Hills or Purvanchal: The North-Eastern Mountain Extension

  The Eastern Hills, collectively known as Purvanchal, represent the southward, lower-elevation extension of the Himalayan system along India's northeastern frontier, defining the border with Myanmar.

  • Topography, Role as Watershed, and Major Regional Ranges

    Characterized by a series of low hills covered in dense forest, the Purvanchal region is vital for its ecological significance and its role as a geographical divider.

    • (i) Topography and Elevation: The hills are relatively low, with elevations ranging from less than 1,500 meters in the Mizo Hills to a high of about 3,826 meters in the Naga Hills. They form a convex shape towards the west.

      

    • (ii) Significance: The Purvanchal acts as a crucial watershed between India and Myanmar, featuring incredibly diverse flora and fauna due to its high rainfall and unique location.
    • (iii) Major Ranges: The region is composed of several localized hill ranges, including the Patkai Bum Hills (known for strong sandstone formations), the Naga Hills (with Saramati being the highest peak), the Barail Range, and the Mizo Hills (featuring Blue Mountain). The Jaintia, Khasi, and Garo Hills are geologically part of the Indian peninsular block but are closely associated with this region.

• Summary: The Enduring Geographical Importance of Himalayan Divisions for Students

  The geographical division of the Himalayan mountain system into the Shiwaliks, Lesser Himalayas, Greater Himalayas, Trans-Himalayas, and Purvanchal provides a complete picture of India's physiography. Understanding the unique characteristics, elevation, and geology of each parallel range is indispensable for mastering physical geography. The study of duns, passes, and regional names associated with these ranges is a key area for students preparing for competitive examinations, emphasizing the interconnected nature of India's landforms and climate.