MP Board Class 8th Social Science Solutions Chapter 7 Changing Outer Forces
MP Board Class 8th Social Science Chapter 7 Text Book Exercise
Choose the correct option of the following
By which process the materials of broken rocks assemble at its original place
Where among the following winds perform its work?
(a) In deserts
(b) In Mountains
(c) In coastal areas
(d) In plains
(a) In deserts
Which is vital factor that makes soil fer-tile?
(a) The original rock materials
Fill in the blanks:
- When the rock breaks into pieces without chemical reaction is …………… weathering
- The process of flattening of unleavened surface is called ………….
- With the deposition …………. lake is formed.
- On the Orissa coast in India …………. is an example of lagoon-lake.
- Surface Balancing
- Chilka Lake
MP Board Class 8th Social Science Chapter 7 Very Short Answer Type Questions
Which are the three works of river?
Erosion, Transportation & Deposition are three works of river.
Which are three stages of river?
There are three stages of river, young, matured and old age.
What is estuary?
Some of the rivers become wider at their meeting point with sea and sweep away into deep sea.
What is geyser?
The underground hot water is thrown up in the form of fountain is called geyser.
How is the Yardage formed?
Yardage is formed by wind erosion.
What is Lagoon?
The sea water enclosed between the coast and sand bar is known as lagoon.
MP Board Class 8th Social Science Chapter 7 Short Answer Type Questions
Write the factors that help soil formation?
The weathering and erosion process of rocks from the soil. The helping agents in soil formation are parent rocks, surface shape, climate & vegetation.
What is weathering? Write the names of different types of weathering?
Weathering is the iocal process in which graduation and split of rocks occur at their original place. The types are physical, chemical and biological weathering.
Differentiate between slow and rapid wasting?
The process of surface sliding by weathering is slow wasting and the process of filling up the holes is high wasting.
How the V – shaped valley is formed?
The V – shaped valley is formed when river reaches its base level and widens its banks. V – Shaped Valley
What are Moraines? Write its types?
When the glacier melts, it starts depositing the sediments in different parts of the valley. The land form made is Moraines. The types are Lateral, Medial and Terminal moraines.
What is underground water level?
The water which collects on the ground goes in to under the ground is called underground water. Water reaches into ground through rivers, lakes and sea.
MP Board Class 8th Social Science Chapter 7 Long Answer Type Questions
Discuss the surface Balancing?
The widening and flattening of the surface is called surface Balancing. Rivers, glaciers, wind, underground water and sea waves are the key agents of leveling. The Surface Balancing can be classified in to two categories.
- Slow wasting
- Rapid wasting.
1. Slow wasting:
The rapid erosion cycle shifts the rocks from its original place by rubbing, cut-ting & peeling to decrease the high elevated areas.
2. Rapid wasting:
The process of deposition of weathered materials in low-lying regions or holes is called aggravation and the weathered materials fill up the holes whose height kept on growing is called Rapid wasting.
What is soil erosion? Write its cause and ways to conserve soil?
The natural forces or human activities which help in removing the layer of soil is called soil erosion. The causes of soil erosion are as follows:
- When the cover of vegetation is removed the upper layer of soil gets loose.
- Heavy rains and powerful wind remove the Soil content and layer.
- Overgrazing by domestic animals.
- Cutting trees and clearing forest cover.
- Excess use of fertilize & pesticide.
The measures to conserve soil are:
- To protect forest. Trees tighten the soil material.
- Tree plantation in river valleys, barren land and mountain slopes.
- Soil rehab of the land which becomes uneven due to water can be leveled to stop erosion.
- Controlled grazing.
- Flood control measures by building stop dams.
- Crop rotation by planting crops alter – neatly.
How wind erosion takes place? Mention about the land forms created by the wind?
The wind erosion generally occurs in Desert areas where wind brings pebbles and sand particles with it. These particles make friction among themselves and scratch rocks. The work of erosion is done by transportation, collision and friction. Wind erosion is affected by the speed of wind, the size, quantity and height of particles, the structure and shape of rocks, and the climate. The land forms created by the wind erosion are sand dunes and Leos.
When some obstacle comes in the path of the sand laden wind the deposition of sand forms a dune hill which has a crest.
Fine particles of the sand are suspended in wind. They are carried over long distance and gets deposited as Loess.
What is glacier? Write about glacier types with example.
A river of moving ice is called glacier. It creeps down a valley from a snowfield above the snow line. It moves under the influence of gravity. On the basis of origin and situation glaciers can be divided into two groups.
1. Continental glacier:
These are permanent sheets of ice and snow that covers extensive land surfaces. These exist in Greenland and Antarctica.
2. Valley glacier:
These are formed in high mountains and are usually long and narrow as they occupy valleys of former streams. The biggest valley glacier is Siachen glacier.
Describe the function of underground water with pictures?
The writer which collects on the ground goes into under the ground is called underground water. Water reaches into ground through rivers, lakes, and sea. Ground water partly exists on the surface like waterfall, artesian well and geyser. Ground water balances the surface and several land forms are created through erosion and transportation. Ground water dilutes the limestone by rain water entering in causes erosion which is called Karts topography
The erosion work of ground water can be classified into two parts:
- landscape or the surface
- underground landscape.
The land forms created on the surface are lapses and sink hole. The underground land form includes caves, stalactites stalagmites.