Worksheet Solutions: Structure and Physiography | Geography Class 11 - Humanities/Arts PDF Download

Fill in the Blanks

Q1: The Earth is approximately ______ million years old.
Ans: 460 million years old
This sentence provides the age of the Earth.

Q2: Endogenic and exogenic forces have played a significant role in shaping the Earth's _______.
Ans: Surface and subsurface features
Endogenic forces originate from within the Earth and include processes like plate tectonics. Exogenic forces, on the other hand, act on the Earth's surface and include processes like erosion and weathering.

Q3: The Indian plate was to the ______ of the equator millions of years ago.
Ans: South
This sentence indicates the past location of the Indian plate in relation to the equator.

Q4: The Australian plate was a part of the ______ plate.
Ans: Indian
This sentence mentions the historical connection between the Australian and Indian plates.

Q5: The northward movement of the Indian plate is still _______.
Ans: Continuing
The sentence highlights that the Indian plate is still in motion towards the north.

Q6: The present geological structure and geomorphologic processes in India are a result of the interplay of _______.
Ans: Endogenic and exogenic forces and lateral movements of the plates
This sentence explains the factors responsible for shaping India's geological structure and landforms.

Q7: India can be divided into three geological divisions based on its _______.
Ans: Geological structure and formations
The divisions are based on variations in India's geological features.

Q8: The Peninsula is primarily formed by ancient _______ and _______.
Ans: Gneisses and granites
The composition of the Peninsula is described, consisting of ancient rocks like gneisses and granites.

Q9: The rift valleys of the Narmada, Tapi, and Mahanadi are examples of _______.
Ans: Features in the Peninsula
These rift valleys are mentioned as specific examples of geological features within the Peninsula.

Q10: The deltas formed by the Mahanadi, Krishna, Kaveri, and Godavari rivers are located in the _______.
Ans: Peninsula
This sentence specifies the location of the river deltas within the Indian Peninsula.

Assertion and Reason Based

Q1: Assertion: The Himalayas are tectonic in origin.
Reason: The Himalayas are composed of young, weak, and flexible rocks.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.
Ans: (a)
The Assertion is true because the Himalayas are indeed tectonic in origin. The Reason is also true as it correctly describes the geological characteristics of the Himalayas, which makes it a tectonic region.

Q2: Assertion: The Peninsular Block is characterized by a stable geological structure.
Reason: The Peninsular Block is subject to frequent volcanic activity.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.
Ans: (b)
The Assertion is true because the Peninsular Block has a relatively stable geological structure. However, the Reason is not the correct explanation, as volcanic activity is not a characteristic of the Peninsular Block.

Q3: Assertion: The Indo-Ganga-Brahmaputra Plain was formed during the third phase of Himalayan mountain formation.
Reason: The plain has been gradually filled by sediments brought by Himalayan and Peninsular rivers.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.
Ans: (a)
The Assertion is true because the plain did form during the third phase of Himalayan mountain formation. The Reason is also true and explains how the plain was gradually filled by sediment brought by rivers.

Q4: Assertion: The Himalayas act as a physical barrier between the Indian subcontinent and Central and East Asian countries.
Reason: The Himalayas have a uniform north-south orientation throughout their entire length.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.
Ans: (b)
The Assertion is true as the Himalayas do act as a physical barrier. The Reason is true and explains how the Himalayas' orientation contributes to this barrier effect.

Q5: Assertion: The Arunachal Himalayas have the highest hydro-electric power potential in India.
Reason: These ranges are characterized by slow-flowing rivers and shallow gorges.
(a) Both Assertion and Reason are true, and Reason is the correct explanation of the Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.
Ans: (d)
The Assertion is true as the Arunachal Himalayas do have high hydro-electric power potential. The Reason is true and explains the characteristics contributing to this potential.

Very Short Answer Type Questions

Q1: Explain the concept of endogenic forces.
Ans: Endogenic forces are geological forces that originate from within the Earth's interior. They include processes like plate tectonics, volcanic activity, and mountain building.

Q2: What is the significance of the Indian plate's northward movement?
Ans: The northward movement of the Indian plate contributes to the collision with the Eurasian plate, leading to the formation of the Himalayan mountains. It also affects the physical environment of the Indian subcontinent.

Q3: Name the three geological divisions of India based on variations in its geological structure.
Ans: The three geological divisions of India are the Peninsula, the Himalayas and other Peninsular Mountains, and the Indo-Ganga-Brahmaputra Plain.

Q4: Define the term "physiography."
Ans: Physiography refers to the study of the physical features, landforms, and surface characteristics of a geographical area, including its relief, topography, and geological structures.

Q5: Differentiate between the Peninsular Block and the Himalayas in terms of geological structure.
Ans: The Peninsular Block has a stable geological structure with ancient rocks like gneisses and granites. In contrast, the Himalayas have a tectonic and young geological structure.

Q6: List some landforms indicative of the youthful stage in the Himalayas.
Ans: Landforms like gorges, V-shaped valleys, rapids, and waterfalls are indicative of the youthful stage in the Himalayas.

Q7: How did the Indo-Ganga-Brahmaputra Plain form?
Ans: The Indo-Ganga-Brahmaputra Plain was formed by the deposition of sediments carried by the Himalayan and Peninsular rivers over millions of years.

Q8: What is the average depth of alluvial deposits in the plains of the Indo-Ganga-Brahmaputra Plain?
Ans: The average depth of alluvial deposits in the plains of the Indo-Ganga-Brahmaputra Plain ranges from 1,000 to 2,000 meters.

Q9: How have geological and geomorphological processes influenced the relief and physiography of India?
Ans: Geological and geomorphological processes, including plate tectonics and erosion, have shaped India's relief and physiography by creating mountain ranges, plateaus, plains, and river valleys.

Q10: What role do the Himalayas play in shaping India's climate and culture?
Ans: The Himalayas act as a climatic barrier, influencing India's climate by blocking cold winds from the north. They also have cultural significance as they divide regions with distinct languages, traditions, and lifestyles.

Short Answer Type Questions

Q1: Explain the movement of the Indian plate and its consequences on the Indian subcontinent's physical environment.
Ans: The Indian plate is moving northward and colliding with the Eurasian plate. This collision has led to the formation of the Himalayan mountains, affecting the landscape, climate, and culture of the Indian subcontinent.

Q2: Describe the geological characteristics of the Peninsular Block.
Ans: The Peninsular Block is primarily composed of ancient rocks like gneisses and granites. It has a stable geological structure compared to the Himalayas. The region has experienced block faulting, leading to rift valleys and block mountains.

Q3: Discuss the significance of rift valleys and block faulting in the Peninsular Block.
Ans: Rift valleys like the Narmada, Tapi, and Mahanadi are examples of block faulting, contributing to the region's topography. The Satpura block mountains are another result of block faulting in the Peninsular Block.

Q4: Explain the physiographic divisions of India based on macro variations.
Ans: The physiographic divisions of India based on macro variations are the Northern and North-eastern Mountains (including the Himalayas and Northeastern hills), the Northern Plain (Indo-Ganga-Brahmaputra Plain), the Peninsular Plateau (stable Peninsular Block), and additional divisions like the Indian Desert, Coastal Plains, and Islands based on specific features.

Q5: Describe the major sub-divisions of the Himalayas.
Ans: The major sub-divisions of the Himalayas include the Greater Himalayan Range (comprising the Great Himalayas and the Trans-Himalayan range), the Middle Himalayas, and Shiwalik (located in the northwestern part of India). The ranges vary in orientation, impacting local climates, and the Great Himalayan range spans 2,500 km with varying width.

Q6: Discuss the geological characteristics of the Arunachal Himalayas.
Ans: The Arunachal Himalayas stretch from the east of Bhutan Himalayas to the Diphu pass. They have a southwest to northeast alignment and feature mountain peaks like Kangtu and Namcha Barwa. The region has perennial rivers with high hydro-electric power potential and is home to various ethnic tribal communities.

Q7: Explain the physiography of the Eastern Hills and Mountains.
Ans: The Eastern Hills and Mountains extend from north to south and are known by different names like Patkai Bum, Naga hills, Manipur hills, or Mizo/Lushai hills. They comprise low hills with many small rivers and feature unique elements like the large lake called 'Loktak' in Manipur and a 'Molassis basin' in Mizoram.

Q8: Discuss the role of Jhum cultivation in the Arunachal Himalayas.
Ans: Jhum cultivation, also known as shifting or slash and burn cultivation, is practiced by various ethnic tribes in the Arunachal Himalayas. Indigenous communities have preserved biodiversity due to the rugged topography associated with Jhum cultivation. Limited inter-valley transportation necessitates interactions through the duar region along the Arunachal-Assam border.

Long Answer Type Questions

Q1: Describe the formation and geological characteristics of the Peninsular Block.
Ans: The Peninsular Block is a major physiographic division of India that is located south of the Northern Plain. It is characterized by its ancient rocks and diverse landforms.
The Peninsular Block is composed of hard and crystalline rocks, such as granite, gneiss, and schist. These rocks were formed during the Archean period, around 3.4 billion years ago. The block has undergone extensive tectonic activity over millions of years, resulting in various geological features.
One of the prominent features of the Peninsular Block is the presence of rift valleys and block faulting. Rift valleys, such as the Narmada and Tapi valleys, were formed due to the faulting and sinking of land along the rift zones. Block faulting has resulted in the formation of horsts (uplifted blocks) and grabens (down-dropped blocks), creating a highly dissected landscape.
The Peninsular Block also exhibits relict and residual mountains. Relict mountains, such as the Aravalli Range and the Vindhya Range, were formed during ancient orogeny (mountain-building) processes but have since been eroded to a much lower elevation. Residual mountains, on the other hand, are remnants of old fold mountains that have undergone extensive erosion, leaving behind resistant peaks, such as the Western Ghats and the Eastern Ghats.
The Peninsular Block is further characterized by its river valleys and deltas. Rivers like the Godavari, Krishna, and Kaveri have carved deep valleys through the block, creating spectacular landscapes. In addition, the deltas formed by these rivers, such as the Krishna Delta and the Kaveri Delta, are fertile regions and important agricultural areas.
Overall, the Peninsular Block is a geologically ancient region with a complex and diverse landscape shaped by tectonic forces, erosion, and sedimentation processes over millions of years.

Q2: Explain the geological and geomorphological processes that have shaped the Indian subcontinent's physiography.
Ans: The physiography of the Indian subcontinent has been shaped by a combination of endogenic and exogenic forces over millions of years. These processes have influenced the formation of its diverse landforms and geological features.
Endogenic forces, primarily plate movements, have played a significant role in shaping the physiography of the Indian subcontinent. The Indian plate, which was originally a part of the supercontinent Gondwana, started drifting northward around 150 million years ago. The collision between the Indian plate and the Eurasian plate gave rise to the Himalayas and the Tibetan Plateau. This collision resulted in intense folding, faulting, and uplift of the Earth's crust, leading to the formation of high mountain ranges, deep valleys, and plateaus.
Exogenic forces, such as erosion, weathering, and sedimentation, have also played a crucial role in shaping the physiography of the Indian subcontinent. The major rivers, such as the Ganges, Brahmaputra, and Indus, have eroded the Himalayas and transported sediment to the plains, resulting in the formation of fertile alluvial plains. Wind and water erosion have sculpted the arid landscapes of the Thar Desert and the coastal dunes.
The geological processes have also influenced the formation of three major geological divisions in India. These divisions are the Himalayas, the Indo-Gangetic Plain, and the Peninsular Plateau. The collision between the Indian and Eurasian plates formed the Himalayas, while the sedimentation of the alluvial plains formed the Indo-Gangetic Plain. The Peninsular Plateau, on the other hand, is a result of ancient tectonic activity and erosion processes.
These geological and geomorphological processes have had a profound impact on the relief and physiography of the Indian subcontinent. They have created diverse landforms, including mountains, plains, plateaus, valleys, and coastal features. The physiographic variations have also influenced the climate, vegetation, and human settlement patterns across the subcontinent.

Q3: Discuss the physiographic divisions of India based on macro variations.
Ans: India can be divided into several physiographic divisions based on macro variations in its landforms and geological features.
These divisions are as follows:

• Northern and North-eastern Mountains: This division includes the Himalayas and the associated ranges, such as the Karakoram, Pir Panjal, and Zanskar ranges. These mountains form a natural boundary between India and its neighboring countries and are characterized by high peaks, deep valleys, and glaciated landscapes. The region is prone to earthquakes and is a major source of perennial rivers.
• Northern Plain: This division is a vast alluvial plain formed by the deposition of sediment brought down by the rivers originating from the Himalayas. It stretches from Punjab in the west to West Bengal in the east and is characterized by fertile soils, extensive agriculture, and densely populated cities.
• Peninsular Plateau: The Peninsular Plateau is a large, triangular-shaped region located south of the Northern Plain. It is composed of ancient rocks, such as granite, gneiss, and schist, and is characterized by diverse landforms. The plateau is dissected by rivers, which have formed deep valleys and gorges. It is also home to relict and residual mountains, such as the Western Ghats and the Eastern Ghats.
• Indian Desert: The Indian Desert, also known as the Thar Desert, is located in the northwestern part of India. It is a large arid region characterized by sand dunes, sparse vegetation, and extreme temperatures. The region is sparsely populated and is home to a unique desert ecosystem.
• Coastal Plains: India has a long coastline stretching over 7,500 kilometers, which is divided into the Western Coastal Plain and the Eastern Coastal Plain. These plains are formed by the deposition of sediments brought by rivers and the action of waves and tides. They are characterized by sandy beaches, lagoons, estuaries, and mangrove forests.
• Islands: India has two major island groups, the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea. These islands are of volcanic origin and are known for their rich biodiversity, coral reefs, and pristine beaches.

These physiographic divisions represent the macro variations in India's landforms and geological features, each with its unique characteristics and ecological significance.

Q4: Describe the Himalayas as a physical, climatic, drainage, and cultural divide in the Indian subcontinent.
Ans: The Himalayas, the world's highest mountain range, serve as a significant physical, climatic, drainage, and cultural divide in the Indian subcontinent.
Physically, the Himalayas act as a formidable barrier between the Indian subcontinent and the rest of Asia. The mountain range stretches over 2,500 kilometers, forming a natural boundary between India and its neighboring countries, including Nepal, Bhutan, Tibet (China), and Pakistan. The towering peaks and deep valleys of the Himalayas make it difficult for easy movement across the region, creating natural borders.
Climatically, the Himalayas play a crucial role in influencing weather patterns in the Indian subcontinent. The range acts as a barrier to the southward movement of cold winds from Central Asia, resulting in the formation of a distinct climatic divide. The northern side of the Himalayas experiences a cold and dry climate, while the southern side receives heavy monsoon rains, leading to stark differences in temperature and precipitation.
The Himalayas also serve as a drainage divide, separating major river systems in the Indian subcontinent. The snowmelt and rainfall in the Himalayas feed several perennial rivers, including the Ganges, Brahmaputra, and Indus. These rivers flow through deep gorges and valleys, providing water for irrigation, hydropower, and other economic activities. The rivers originating from the Himalayas have shaped the fertile plains and deltas, supporting agriculture and human settlements.
Culturally, the Himalayas have played a significant role in shaping the diversity and cultural practices of the Indian subcontinent. The region is home to several ethnic groups, each with its distinct languages, traditions, and belief systems. The Himalayas also hold great religious significance, with pilgrimage sites and monasteries attracting millions of devotees and tourists from around the world. The cultural diversity and spiritual significance of the Himalayas have contributed to the rich tapestry of Indian culture.
In conclusion, the Himalayas act as a physical, climatic, drainage, and cultural divide in the Indian subcontinent. Its towering peaks, climatic variations, role in river systems, and cultural significance make it a unique and influential feature of the region.