3.2 Text Questions :
Answer the following questions :
1. Why do the plates move?
Ans: The plates move because of the movement of molten magma inside the earth.
2. What are exogenic and endogenic force?
Ans: The force that works on the surface of the earth is called exogenic force.
The force that act in the interior of the earth is called endogenic force.
3. What is erosion?
Ans: Erosion is the wearing away of the landscape by different agents like water, wind and ice.
4. How are flood plains formed?
Ans: During floods , layers of fine soil and other material called sediments are deposited on the river banks. This leads to the formation of a flat fertile flood plains.
5. What are sand dunes?
Ans: Sand dunes are low hill-like structures formed by the deposition along the shores of the sea.
6. How are beaches formed?
Ans: Beaches are formed when the sea waves deposit sediments along the shores of the sea.
7. What are ox-bow lakes?
Ans: When the meander loop is cut off from the main river, it forms a cut-off lake. As its shape is like an ox bow, it is known as ox-bow lake.
Tick the correct answer :
1. Which is not an erosional feature of sea waves?
(a) Cliff (b) Beach (c) Sea cave √
2. The depositional feature of a glacier is _____ .
(a) Flood plain (b) Beach (c) Moraine √
3. Which is caused by the sudden movements of the earth?
(a) Volcano √ (b) Folding (c) Flood plain.
4. Mushroom rocks are found in ______ .
(a) Deserts √ (b) River valleys (c) Glaciers
5. Ox bow lakes are found in ________ .
(a) Glaciers (b) River valleys √ (c) Deserts.
Match the following :
(i) Glacier (a) sea shore
(ii) Meanders (b) river of ice.
(iii)beach (c) Rivers
(iv)Sand dunes (d) Vibrations of earth.
(v)Waterfall (e)Hard bed rock.
(vi) Earthquake (f) Deserts
Answers :
i) Glacier — (b) river of ice.
ii) Meanders — (e) Hard bed rock.
iii) Beach — (a) Sea shore.
iv) Sand dunes — (f) Deserts.
v) Waterfall — (c) Rivers
vi) Earthquake — (d)Vibrations of earth.
Give reasons :
1. Some rocks have a shape of a mushroom.
2. Flood plains are very fertile.
3. Sea caves are turned into stacks.
4. Buildings collapse due to earthquakes.
Answers :
1. Some rocks have a shape of a mushroom .
Ans : In deserts, winds usually erode the lower section of the rock more than the upper part. Therefore such rocks have narrower base and wider top which takes the shape of a mushroom.
2. Flood plains are very fertile.
Ans : Flood plains are formed by the deposition of fine soil and other material called sediments on the river banks. As the soil and sediments are brought by flood water, they are very fertile.
3. Sea Waves are turned into stacks.
Ans : Sea waves strike at the rocks. As a result cracks develop which become bigger over time and hollow like caves are formed on the rocks. They are called sea caves.These cavities become bigger and bigger and a time comes when only the roof of the caves remain to form sea arches. Further erosion breaks the roof and only walls are left. These wall like feature are called stacks. In this way sea caves are turned into stacks.
4. Buildings collapse due to earthquakes.
Ans : Most of the buildings are not safe enough to resist the vibrations of the earthquakes. They are not made earthquake proof. They collapse tearing apart due to shallow foundation and lack of adequate steel in the interior design.
FOR FUN:
Solve the crossword puzzle with the help of given clues :
Across :
1. Loop like bend of river .
2. Solid form of water .
3. Moving mass of ice .
4. Sudden descent of water in bed of river .
5. Natural cavity on weak rocks formed by action of waves .
6. Embankment on river that keeps river in its channel .
7. Large body of sea water .
8. Dry area where sand dunes are found .
9. Small hill of sand piled by action of wind .
10. Flat plain formed by river deposits during time of flood .
Down :
1. Rise and fall of water caused by friction of wind on water surface .
2. Flow of water in channel .
3. Steep perpendicular face of rock along the sea coast .
4. Debris of boulder and coarse material carried by glacier .
5. Crescent shaped lake formed by river meander .
6. Fine sand deposited by action of wind .
7. Isolated mass of rising steep rock near coastline .
8. Alluvial tracts of land at mouth of river formed by river deposits .
Answers :
Across :
1. Loop like bend of a river – MEANDER .
2. Solid form of water – ICE .
3. Moving form of ice – GLACIER .
4. Sudden descent of water in bed of river – WATERFALL .
5. Natural cavity on weak rocks formed by action of waves – CAVE .
6. Embankment on river that keeps river in its channel – LEVEE .
7. Large body of sea water – SEA .
8. Dry area where sand dunes are found – DESERT .
9. Small hill of sand piled by action of wind – SAND DUNE .
10. Flat plain formed by river deposits during time of flood – FLOOD PLAIN .
Down :
1. Rise and fall of water caused by friction of wind on water supply – WAVE .
2. Flow of water in channel – RIVER .
3. Steep perpendicular face of rock along the sea coast – CLIFF .
4. Debris of boulder and coarse material carried by glacier – MORAINE .
5. Crescent shaped lake formed by river meander – OX BOW LAKE .
6. Fine sand deposited by action of wind – LOESS .
7. Isolated mass of rising steep rock near coastline – STACK .
8. Alluvial tracts of land at mouth of river formed by river deposits – DELTA .