Outer Himalayas, also known as the Shiwalik Range, is situated between the Great Plains and the Lesser Himalayas. The elevation ranges from 600 to 1500 metres. It stretches 2,400 kilometres from the Potwar Plateau to the Brahmaputra Valley. The southern slopes are steeper than the northern slopes. The Shiwaliks range in width from 50 km in Himachal Pradesh to less than 15 km in Arunachal Pradesh. This article will explain to you about the Outer Himalayas (or Shiwalik) which will be helpful in Geography preparation for the UPSC Civil service exam.

Outer Himalayas (or Shiwalik)

• The Shivalik ranges are the Himalayas' southernmost hills. It is separated from the Lesser Himalayas by valleys with flat bottoms. The ancient name for this range was "Upgiri."
• The Outer Himalayas form a continuous chain of over 2400 km. from the northwest Indus gorge to the Brahmaputra in Assam
• The height rarely exceeds 1300 m, and the width of the Shivaliks ranges from 10 to 50 kilometres.
• The southern slopes of the Shivalik ranges in Himachal Pradesh and Punjab are devoid of forest cover. Chaos, the seasonal stream, has severely eroded these slopes.
• Between the Himachal and Shivalik ranges, many longitudinal valleys run parallel to the mountains known as 'Duns,' such as Patli Dun, Kotli Dun, and Dehradun.

Outer Himalayas (or Shiwalik)

Outer Himalayas (or Shiwalik) - Importance

• The Shiwalik range from North-East India to Nepal is densely forested, but the forest cover decreases west of Nepal (The quantum of rainfall decreases from east to west in Shiwaliks and Ganga Plains).
• The Shivalik range's southern slopes in Punjab and Himachal Pradesh are almost devoid of forest cover. Seasonal streams known as Chos cut deeply into these slopes.
• Valleys are part of synclines, while hills are part of anticlines or anti-synclines.
• The Siwalik Mountains are sometimes thought to include the southern hills of the Assam Himalayas, which extend eastward for 400 miles across southern Bhutan to the Brahmaputra River. The Shiwaliks are the Himalayas' most isolated range.
• These categories' three main characteristics are
• They have a diameter of 10-50 km and a height of 900-1100 metres.
• These sections are made up of uncoordinated rivers that flow south from the main Himalayas.
• Dense alluvium rocks cover these valleys.
• The Duns are the names given to the long valley that runs between the small Himalayas and the Shiwaliks, including DehraDun, Kotli Dun, and Patli Dun.
• Different areas have different names for the Shiwaliks.

Shivalik Range

Formation of Duns (Duras)

• Shivalik Hills were formed by conglomerate accumulation (sand, stone, silt, gravel, debris, etc.).
• During the initial stages of deposition, these conglomerates obstructed the courses of rivers draining from the higher reaches of the Himalayas, forming temporary lakes.
• These temporary lakes accumulated more and more conglomerates as time passed. The conglomerates had settled well at the lakes' bottoms.
• When rivers were able to cut their paths through lakes filled with conglomerate deposits, the lakes were drained away, leaving behind plains known as 'duns' or 'duns' in the west and 'duars' in the east.
• The best example is Dehradun, Uttarakhand.
• Other notable dunes include Kotah, Patli Kothri, Chumbi, Kyarda, Chaukhamba, Udhampur, and Kotli.

Conclusion

The Shiwalik Range, commonly known as the Outer Himalayas, is located between the Great Plains and the Lesser Himalayas. The Shiwalik range stretches from North-East India to Nepal, but forest cover reduces west of Nepal. Dehradun, Kotli Dun, and Patli Dun are names given to the long valley that stretches between the Little Himalayas and the Shiwaliks. The Shiwaliks are known by many names in different locations.

FAQs

MCQs

1. Which of the following best describes the Shiwalik Range?

A) The highest range of the Himalayas
B) The southernmost range of the Himalayas
C) A volcanic range in southern India
D) A plateau region in central India

2. What is the geological composition of the Shiwalik Hills?

A) Basalt and granite
B) Sandstone, conglomerates, and siltstones
C) Limestone and chalk
D) Marble and schist

3. Which valley is located between the Shiwalik and the Middle Himalayas?

A) Kangra Valley
B) Narmada Valley
C) Ganga Valley
D) Godavari Valley

4. In which geological period were the Shiwalik Hills formed?

A) Cretaceous
B) Tertiary
C) Jurassic
D) Precambrian

5. What type of ecosystem is found south of the Shiwalik Hills?

A) Arid desert
B) Mangrove forests
C) Terai region
D) Alpine tundra

GS Mains Questions and Model Answers

Q1: Discuss the geological significance of the Shiwalik Range in the context of Himalayan formation.

Answer: The Shiwalik Range plays a significant role in the overall structure of the Himalayan mountain system. Formed during the Tertiary Period, the Shiwaliks are composed of unconsolidated sediments such as sandstone, conglomerates, and siltstones. These sediments were deposited by rivers flowing from the higher Himalayas. The Shiwaliks are geologically younger and more fragile than the Middle and Greater Himalayas. Their formation is closely linked to the ongoing tectonic activity in the region, which continues to shape the Himalayan landscape through processes like erosion, sedimentation, and uplift.

Q2: Analyze the environmental challenges faced by the Shiwalik region and suggest measures to address them.

Answer: The Shiwalik region faces several environmental challenges, including deforestation, soil erosion, landslides, and habitat degradation. These issues are exacerbated by human activities such as unplanned development, agriculture, and infrastructure projects. The fragile geology of the region, composed of unconsolidated sediments, makes it particularly prone to landslides. To address these challenges, measures such as afforestation, sustainable land-use practices, and the construction of soil conservation structures can help stabilize the region. In addition, promoting eco-friendly development and implementing disaster management plans can mitigate the impacts of environmental degradation.

Q3: Explain the role of the Shiwalik Range in shaping the hydrology and biodiversity of northern India.

Answer: The Shiwalik Range plays a crucial role in the hydrology and biodiversity of northern India. The range serves as a natural barrier, influencing the flow of rivers and the distribution of rainfall in the region. The valleys between the Shiwalik and Middle Himalayas, known as duns, are rich in water resources and support agriculture and human settlements. The Terai region south of the Shiwaliks is characterized by marshes and dense forests, which serve as important habitats for diverse wildlife species, including elephants, tigers, and rhinoceroses. The Shiwalik ecosystem is vital for maintaining the ecological balance and supporting livelihoods in northern India.

Previous Year Questions on Shiwalik Range

1. UPSC CSE Prelims 2019

Question: Which of the following valleys is located between the Shiwalik and Middle Himalayas?
A) Doon Valley
B) Kashmir Valley
C) Kangra Valley
D) Narmada Valley

Answer: A

Explanation: The Doon Valley is located between the Shiwalik and Middle Himalayan ranges. It is one of the most fertile valleys in northern India, known for its agricultural importance.

2. UPSC CSE Mains 2020 (GS Paper 1)

Question: Discuss the environmental vulnerability of the Shiwalik Range and suggest mitigation measures to address the issues.

Answer: The Shiwalik Range is highly vulnerable to landslides, soil erosion, and deforestation due to its composition of unconsolidated sediments. Unplanned development and deforestation have further exacerbated these issues. Mitigation measures include afforestation programs, the construction of check dams to control soil erosion, and promoting sustainable agricultural practices. Additionally, strengthening disaster preparedness and implementing early warning systems for landslides can help minimize the environmental risks in the Shiwalik region.