Physical Features of India - Class IX Chapter 2 Notes
INTRODUCTION
India's present physical form results from vast geological formations.
Key aspects: Stratigraphy, geological structure, and physiography.
The Indian Peninsula was part of Gondwana, shifted northward, colliding with the central Asiatic plate, forming the Himalayas from the Tethys Sea.
Diverse physiographic units complement each other:
Mountains: Water and forest source.
Northern Plain: Granary of the country.
Plateau: Mineral storehouse.
Coast: Fishing and port activities.
OBJECTIVES
Familiarization with India's physical features.
Comparative study of regional linkages.
Understanding continent and mountain building, combined with erosion agents.
Develop map work skills and appreciate nature.
MAJOR PHYSIOGRAPHIC DIVISIONS
Three major landforms grouped into seven physiographic units:
A) The Himalayan Mountain
1. Northern Mountains
B) The Indo-Gangetic Plain
2. Great Plains
3. Thar Desert
C) Peninsular Plateau
4. Central Highlands
5. Peninsular Plateaus
6. Coastal Plain
7. Islands
AREA AND PERCENTAGE OF PHYSICAL UNITS
Areas (sq km) and percentages occupied:
Northern Mountains: 578,000
Great Plains: 550,000
Thar Desert: 175,000
Central Highlands: 336,000
Peninsular Plateaus: 1,241,000
Coastal Plain: 335,000
Islands: 8,300
PANGEA
Supercontinent formed during the late Paleozoic and early Mesozoic eras.
Formed approximately 335 million years ago.
Broke up about 175 million years ago.
SPLIT OF PANGEA OVER AGES
Describes the geological split of Pangea into present-day continents over millions of years.
Includes key periods like Permian (250 million years ago), Triassic (200 million years ago), Jurassic (145 million years ago), and Cretaceous (65 million years ago).
Illustrates the positions of continents such as North America, South America, Eurasia, Africa, India, Antarctica, and Australia during these periods.
Highlights the Tethys Ocean and the formation of the Atlantic and Indian Oceans.
TECTONIC PLATE MOVEMENT
Illustrates plate tectonics:
Diverging: Plates move apart.
Converging: Plates collide, causing volcanoes, earthquakes, and trench formation.
Transform: Plates slide past each other, causing earthquakes.
HIMALAYA
Asymmetrical young fold mountain.
Distance: km.
Width: km (Kashmir) to km (Arunachal Pradesh).
INTRODUCTION
India's present physical form results from vast geological formations.
Key aspects: Stratigraphy, geological structure, and physiography.
Stratigraphy: Branch of geology that studies the layering of rocks (strata).
Geological Structure: Refers to the arrangement and organization of rocks and geological features in a specific area. It includes folds, faults, joints, and other deformational structures that have shaped the Earth's crust.
Physiography: Describes the physical features of the Earth's surface, including landforms, bodies of water, and other natural features.
The Indian Peninsula was part of Gondwana, shifted northward, colliding with the central Asiatic plate, forming the Himalayas from the Tethys Sea.
Diverse physiographic units complement each other:
Mountains: Water and forest source.
Northern Plain: Granary of the country.
Plateau: Mineral storehouse.
Coast: Fishing and port activities.
OBJECTIVES
Familiarization with India's physical features.
Comparative study of regional linkages.
Understanding continent and mountain building, combined with erosion agents.
Erosion Agents: Natural forces like water, wind, ice, and gravity that wear away and remove rocks and soil from the Earth's surface.
Develop map work skills and appreciate nature.
MAJOR PHYSIOGRAPHIC DIVISIONS
Three major landforms grouped into seven physiographic units:
A) The Himalayan Mountain
1. Northern Mountains
B) The Indo-Gangetic Plain
2. Great Plains
3. Thar Desert
C) Peninsular Plateau
4. Central Highlands
5. Peninsular Plateaus
6. Coastal Plain
7. Islands
AREA AND PERCENTAGE OF PHYSICAL UNITS
Areas (sq km) and percentages occupied:
Northern Mountains: 578,000
Great Plains: 550,000
Thar Desert: 175,000
Central Highlands: 336,000
Peninsular Plateaus: 1,241,000
Coastal Plain: 335,000
Islands: 8,300
PANGEA
Supercontinent formed during the late Paleozoic and early Mesozoic eras.
Formed approximately 335 million years ago.
Broke up about 175 million years ago.
SPLIT OF PANGEA OVER AGES
Describes the geological split of Pangea into present-day continents over millions of years.
Includes key periods like Permian (250 million years ago), Triassic (200 million years ago), Jurassic (145 million years ago), and Cretaceous (65 million years ago).
Illustrates the positions of continents such as North America, South America, Eurasia, Africa, India, Antarctica, and Australia during these periods.
Highlights the Tethys Ocean and the formation of the Atlantic and Indian Oceans.
Tethys Ocean: Ancient ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic Era.
Formation of the Atlantic Ocean: Began with the rifting of Pangea, leading to the separation of North America from Europe and South America from Africa.
Formation of the Indian Oceans: Formed as India separated from Gondwana and moved northward.
TECTONIC PLATE MOVEMENT
Illustrates plate tectonics:
Diverging: Plates move apart.
Results in the creation of new crust as magma rises from the mantle to fill the gap between separating plates. Examples include the Mid-Atlantic Ridge.
Converging: Plates collide, causing volcanoes, earthquakes, and trench formation.
Occurs when two plates move towards each other. If one plate is denser (usually oceanic), it may subduct beneath the less dense plate (either continental or oceanic).
Transform: Plates slide past each other, causing earthquakes.
Characterized by horizontal sliding motion. As plates move past each other, friction can cause them to lock temporarily.
HIMALAYA
Asymmetrical young fold mountain.
Young Fold Mountain: Mountains formed relatively recently through the folding of the Earth's crust