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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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

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

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

VGS ACADEMY

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