JAC Board Class 9th Social Science Notes Geography Chapter 2 Physical Features of India
- India has practically all the physical features of the Earth like mountains, plains, deserts, plateaus, islands etc.
- Geologically, the land of India displays great physical variation.
→ Major Physiographic Divisions
- The physical features of India can be grouped under the following physiographic divisions: (i) The Himalayan mountains, (ii) The Northern plains, (iii) The Peninsular plateau, (iv) The Indian desert, (v) The Coastal plains, (vi) The Islands.
→ The Himalayan Mountains
- The Himalayan mountains are the major sources of water and forest wealth.
- The Himalayas are geologically young and structurally fold mountains. They stretch over the Northern borders of India.
- The Himalayas consists of three parallel ranges in its longitudinal extent: (i) The Great or Inner Himalayas or the ‘Himadri’, (ii) The Middle or lesser Himalayas or The ‘Himachal’ (iii) The Outer Himalayas or The ‘Shiwaliks’.
- The Himalayas are also divided on the basis of regions from West to East. This demarcation is done by river valleys, i.e. the Indus, Sutlej, Kali, Teesta and Dihang rivers.
- In the west, the part of Himalayas lying between Indus and Sutlej has been traditionally known as Punjab Himalayas.
- The part of Himalayas lying between Sutlej and Kali rivers is known as Kumaon Himalayas.
- The Kali and Teesta rivers demacrate the Nepal Himalayas and the part lying between Teesta and Dihang rivers is known as Assam Himalayas.
- Purvanchal or the Eastern hills and mountains running through the North-Eastern states are mostly composed of strong sand stones, which are sedimentary rocks covered with dense forest.
→ The Northern Plains
- The Northern plains are the granaries of the country. They provided the base for early civilisations.
- The Northern Plain has been formed by the interplay of the three major river systems, namely the Indus, the Ganga and the Brahmaputra along with their tributaries.
- The Northern plain is broadly divided into three sections: (i) The Punjab plains, (ii) The Ganga plains, (iii) The Brahmaputra plains.
- According to the variations in relief features, the northern plains can be divided into four regions:(i) Bhabar, (ii) Terai, (iii) Bangar, (iv) Khadar.
- The largest part of the Northern plain is formed of older alluvium.
→ The Pfehinsular Plateau
- The Peninsular Plateau is a tableland composed of the old crystalline, igneous and metamorphic rocks. This plateau consists of two broad divisions, namely, the Central Highlands, the Deccan Plateau.
- The Western Ghats and the Eastern Ghats mark the western and the eastern edges of the Deccan Plateau respectively.
- The Western part of the plateau, known as the Deccan Trap, contains black soil of volcanic origin.
→ The Indian Desert
- The Indian Desert lies towards the western sides of the Aravalli Hills. It is an undulating sandy plain covered with sand dunes.
- Luni is the only large river in this region.
- This region receives very low rainfall, i.e. below 150 mm per year.
→ The Coastal Plains
- The Peninsular Plateau is boardered by stretches of narrow coastal strips, running along the Arabian Sea on the West and the Bay of Bengal on the east.
- The Western coast consists of three sections (i) The Konkan Coast, (ii) The Kannad Plain (iii)The Malabar Coast.
- The Eastern Coast consists of the Northern Circar and the Coromandel Coast.
→ The Islands
- The Lakshadweep islands group lies close to the Malabar coast of Kerala and are composed of small coral islands.
- The elongated chain of the Andaman and Nicobar islands located in the Bay of Bengal extends from North to South.
→ Mountain: A mountain is a large landform that rises above the surrounding land in a limited area, usually in the form of a peak.
→ Desert: A large dry area, largely devoid of vegetation for want of rain or water.
→ Plateau: A wide, flat, topped area, rising abruptly from the surrounding low-lying area or a water body.
→ Island: A piece of land that is completely surrounded by sea, a river or lake.
→ Valley: A valley is a low area between hills or mountains typically with a river running through it.
→ Ox-bow lake: A crescent-shaped lake on a river floodplain.
→ Fold Mountains: An upland area, such as the Himalayas or Alps formed by the buckling of the Earth’s crust.
→ Physiography: Shape and relief or geographical features of an area.
→ Glacier: A glacier is a huge mass of ice that moves slowly over land.
→ Tributaries: Streams or small rivers that flow into a larger river.
→ Distributary: A river that originates from a major river. It is formed near the river’s mouth before falling into the sea.
→ Waterfall: A waterfall is an area where water flows over a vertical drop or a series of steep drops in the course of a stream or river.
→ Riverine Islands: Islands on a river.
→ Gondwana land: It was an ancient super-continent located in Southern Hemisphere which included the present-day South America, Africa, Australia snd Antarctica.
→ Bhangar: The older alluvium of the Northern Plain is called the Bhangar.
→ Khadar: The younger alluvium of the floodplains is known as the Khadar.
→ Duns: Narrow valleys found between Shiwaliks and Middle Himalayas.
→ Strait: A narrow stretch of water joining two oceans or large water bodies.
→ Barchans: Barchan also spelled Barkhan, crescent-shaped sand dunes produced by the action of wind an predominantly from one direction.
→ Tectonic Plates: Due to internal heat of the Earth, the currents of the semi-molten rocks move towards the crust, and tear it apart, dividing it into large fragments which are called Tectonic Plates.
→ Tethys: An elongated shallow sea sandwiched between two ancient landmasses.
→ Coral: Coral polyps are short-lived microscopic organisms which live in colonies. They flourish in shallow, mud free and warm waters. They secrete calcium carbonate.
→ Atolls: These are circular or horse-shoe-shaped coral reefs. Lakshadweep is one such type.
→ Gorge: The steep-sided narrow and deep valley of a river formed in its upper course is termed as a gorge. It is also called an I-shaped valley.