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SST CLASS 7 DAV CHAPTER 2

  A. Tick the correct option. Answer: 1. (d) formation of mountains 2. (b) Antarctica 3. (a) ‘V’ shaped valley, meander and delta 4. (d) top soil 5. (a) alluvial soil B. Fill in the blanks. 1. Organic matter when gets decomposed in the soil and converts it into dark coloured material is called ___________. 2. ___________ soil is found in a large part of our country. 3. ___________ and ___________ valleys are formed at the youthful stage of a river. 4. A ___________ is a steep sided rock facing the sea. 5. ___________ river and ___________ river form the largest delta of the world. Answer: (1) humus (2) Alluvial soil (3) I shaped, V shaped (4) cliff (5) Ganga, Brahmaputra C. Give a single term for each of the following statements. 1. Mounds of sand deposited by wind action in deserts. 2. The process in which a gradual wearing and carrying away of soil particles takes place on the earth’s surface. 3. The process of laying down of sediments carried by various agents of gradation. 4. A mas
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SST CLASS 7 DAV CHAPTER 1

 A. Tick the correct option. B. Give a single term for each of the following sentences. 1. A situation or condition in which an organism lives. 2. The only planet in our solar system where life exists. 3. The uppermost part of the lithosphere which is rich in silica and aluminium. 4. Sial The sphere of air that envelopes the earth. 5. Mass of water on the earth’s surface. Answer: (1) Biosphere(2) Earth(3) Sial(4) Atmosphere (5) Hydrosphere C. Match the following: 1. Physical environment includes                        a. Atmosphere 2. It is the most dynamic in nature                      b. Human beings      3. A narrow zone supporting life                         c. Non-living things 4. They are capable of modifying environment              d. Biosphere 5. Rocks rich in silica and magnesium                   e. Sima Answer: 1. (c),2. (a), 3. (d), 4. (b), 5. (e) D. Answer the following questions in brief. 1. Name the major components of the environment. Answer: Physical environment and
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DISTRIBUTION OF MAJOR SOIL TYPE

Soil is generally classified on the basis of colour and texture. Alluvial soil: It is found over a large part of India. It is mainly formed by the deposition o of sediments by river and is confined to e northern and coastal plains.,This type of soil is very fertile and forms major agricultural land of our country., Black soil: It is found in Deccan plateau. This type of soil is confined to some parts of Gujarat, Maharashtra and Karnataka. This soil has an ability to retain moisture and become sticky when wet., It is largely used for growing cotton and thus, is popularly. f known as cotton soil. Red soil: As the name suggests, this soil is red in colour due to the of iron.particles, Red soil is confined to peninsular India and some patches of north-eastern parts of India. It is highly porous, fine grained and deep Laterite soil: It is found over the hill slopes of peninsular plateau. The laterite soil is found in the regions of heavy rainfall. It is formed by the leaching process. Apart
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FORMATION OF SOIL

 It is a very slow process. It takes thousands of years to form a thin layer of soil. As mentioned earlier, the weathering process breaks the rocks into small particles. These are then carried away by water, wind, etc., and later get deposited at a new place. Such soil is called transported soil. But,when the soil is formed by the weathering of a parent rock and remains present on the same site, it is called residual soil.The soil forming process continues over a long span of time. It starts developing in layers, one over the other. These layers are called horizons. From bottom to top, the lowest horizon is called bed rock, then comes the horizon of weathered rock and it is followed by the sub soil and top soil. The topmost horizon is rich in humus. 
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SOIL

Soil is the loose material found on the surface of the earth. It is made of organic and inorganic particles. The organic particles are derived from dead remains of plants and animals. In the course of time, these particles get decomposed and change into a dark coloured material called humus. The humus present in the soil contributes to the fertility of the land. This is rapidly formed in humid areas due to heavy growth of plants and rich animal life. However, humus is low in desert soil. The inorganic particles are derived from rocks. They include loose disintegrated particles of different sizes. The large sized particles are called gravel, while the smaller ones are called sand, silt and clay. A mixture of these particles gives rise to different types of soil as per their proportion. These are called sandy, loamy and clayey soils.
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AGENT OF GRADATION

 Running water It is an important agent of gradation. A river, like any living form, has a 'life cycle'. It takes birth in a mountain or a hill, becomes larger where it is met by a number of tributaries, flows over plains and finally ends when it reaches the sea. In its early stage, the river is young. It flows over steep mountains where its rate of erosion is maximum. Due to down cutting work of a river, it forms striking youthful features like 'l' shaped and 'V' shaped valleys, waterfalls, etc. As the river enters into the plains, it comes to the stage of maturity. Here, the volume of water increases and the slope of land decreases, resulting in slow speed of the river. During this stage, the river is said to flow through meanders. Before meeting the sea, the river becomes large and sluggish and gets divided into several distributaries. It now comes to its old stage. The river, thus, deposits silt, sand and sediments over a large area near its mouth. This larg
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FOUR SPHERE OF EARTH

The natural environment can be broadly divided into four spheres, i.e. Lithosphere, Atmosphere, Hydrosphere and Biosphere. Each of these is unique in its own way and supports others in sustaining life forms on our planet called the Mother Earth. Let us understand the importance of each sphere of the natural environment. Lithosphere The literal meaning of 'lithosphere' is the 'sphere of rocks'. The earth's solid layer is called lithosphere.The lithosphere is about 100 km in thickness. The uppermost part of the lithosphere is composed of rocks rich in silica and aluminium called sial. Below the sial layer, the rocks are mainly rich in silica and magnesium and are called sima, which is generally found below the bottom of the ocean basins Thus, lithosphere is that part of the earth which provides us land over which we live. It provides soil for the plants and is also a source of all the mineral wealth) Atmosphere The literal meaning of 'atmosphere' is the 's
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