Landforms Notes 7th Social Science
Landforms Notes 7th Social Science
7th Social Science Lesson 4 Notes in English
4. Landforms
1. What is endogenic Process?
The endogenic process (internal process) leads to the upliftment and sinking of the earth’s surface at several places.
2. What is exogenic Process?
The exogenic process (external process) is the continuous wearing down and rebuilding of the land surface.
3. Define Gradation:
Gradation is the process of levelling of highlands through erosion and filling up of lowlands through deposition.
4. What is Weathering?
Weathering is the breaking and falling apart into small pieces of the rocks on the earth’s surface.
5. Define Erosion:
Erosion is the wearing away of the landscape by different agents like water, wind, ice and sea waves. The eroded material is carried away by water, wind, etc. and eventually deposited. This process of erosion and deposition create different landforms on the surface of the earth.
7th Social Book Back Questions
6. Where do the Rivers Originate?
The water flowing from its source to river mouth, along a definite course is called a River. Rivers generally originate from a mountain or hill.
7. What is River Mouth?
The place of origin of the river is known as its Source. The place where it joins a lake or sea or an ocean is known as the River mouth.
8. Define V Shaped valley:
The running water in the river erodes the landscape, which creates a steep-sided valley like the letter ‘V’ known as ‘V’ shaped valley.
9. Define Tributary:
A stream or river that flows into and joins a main river.
10. Define Distributary:
A stream that branches off and flows away from a main stream.
11. Define Waterfall:
Falling of river water over a vertical step in the river bed is called waterfall. It is formed when the soft rock are removed by erosion. E.g. Coutrallam falls across the river chittar in TamilNadu.
12. Which is the highest waterfall in world?
The highest waterfall is Angel Falls of Venezuela in South America.
13. What are the other major waterfalls?
The other waterfalls are Niagara Falls located on the border between Canada and USA in North America and Victoria Falls on the borders of Zambia and Zimbabwe in Africa.
14. What is Plunge Pool?
Plunge pool is a hollow feature at the base of a waterfall which is formed by cavitation. Alluvial fan is a deposition of sediment occurs at which the river enters a plain or the foot-hills.
15. What is a Meander?
As the river enters the plain it twists and turns forming large bends known as Meanders. Eg. Meanders along the River Vellar near Sethiyathope in Cuddalore District, Tamil Nadu.
16. What is Ox-bow lake?
In due course of time the meander loop cuts off from the river and forms a cutoff lake, also called an Ox-bow lake.
17. Define the term Meander:
The term ‘Meander’ has been named on the basis of Meander River of Asia Minor (Turkey), it flows through numerous curves and turns.
18. What is flood Path?
- At times the river overflows its banks. This leads to the flooding of the neighbouring areas.
- As the river floods, it deposits layers of fine soil and other material called sediments along its banks.
- This leads to the formation of a flat fertile floodplain. The raised banks are called levees.
19. Define Delta:
The velocity of the river becomes so slow that it begins to deposit its load. Each distributary forms its own mouth. The collection of sediments from all the mouths form Delta.
20. How is Delta useful?
Deltas are excellent productive lands. They have more minerals which favour cultivation. E.g. Cauvery delta, Ganges delta, Mississippi delta.
21. Define Glacier:
A large body of ice moving slowly down a slope or valley due to gravity is called a glacier.
22. How are Glacier Grouped?
Glaciers are grouped into Mountain or Valley Glaciers and Continental Glaciers.
23. What is Continental Glacier?
The glacier covering vast areas of a continents with thick ice sheets. E.g. Antarctica, Greenland
24. Define Mountain Glacier:
Mountain or Valley Glacier is a stream of ice, flowing along a valley. It usually follows former river courses and are bounded by steep sides. E.g. The Himalayas and the Alps.
25. What is Cirque?
Cirque is a glacially eroded rock basin, with a steep side wall and steep head wall, surrounding an armchair-shaped depression. E.g. Corrie – Scotland (United Kingdom), Kar – Germany.
26. What is Tarn Lake?
As the ice melts, they get filled up the cirque with water and become beautiful lakes in the mountains called as Tarn Lake.
27. What are Aretes?
When two adjacent cirques erode towards each other, the previously rounded landscape is transformed into a narrow rocky, steep – sided ridge called Aretes.
28. What are Glacial moraines?
- U Shaped Valley is found beneath the glaciers which is deepened and widened by the lateral and vertical erosion.
- The material carried by the glacier such as rocks – big and small, sand and silt get deposited. These deposits form glacial moraines.
29. What is a mushroom rocks?
In deserts you can see rocks in the shape of a mushroom, commonly called mushroom rocks.
30. What is Inselbergs?
- Winds erode the lower section of the rock more than the upper part. Therefore, such rocks have narrower base and wider top.
- An isolated residual hill, standing like a pillar with rounded tops are called Inselbergs. E.g. Inselberg in the Kalahari Desert of South Africa.
31. What are sand dunes?
When the wind blows, it lifts and transports sand from one place to another. When it stops blowing the sand falls and gets deposited in low hill – like structures. These are called sand dunes.
32. The crescent shaped sand dunes are called Barchans.
33. What is Loess?
- When the grains of sand are very fine and light, the wind can carry it over very long distances. When such sand is deposited in large areas, it is called Loess.
- Large deposits of loess are found in China.
34. Northern China loess deposits are brought from the Gobi Desert.
35. What is coast line?
A part of the land adjoining or near the sea is called the Sea coast. The boundary of a coast, where land meets water is called the Coast line.
36. How coastal areas are formed?
The coastal areas are subject to change due to wave erosion and wave deposition. The erosion and deposition of the sea waves give rise to coastal landforms.
37. What is Sea Cliffs?
Sea Cliffs are steep rock faces formed, when the sea waves dash against them.
38. Define Sea waves:
Sea waves continuously strike at the rocks. Cracks develop. Over time they become larger and wider. Thus, hollow like caves are formed on the rocks. They are called Sea Caves.
39. What is a Sea Arches?
As the cavities of sea caves become bigger and bigger only the roof of the caves remains, thus forming Sea Arches.
40. What is Stacks?
Erosion breaks the roof and only walls are left. These wall like features are called Stacks.
41. Define Beaches:
The sea waves deposit sediments of sand and gravel along the shores forming Beaches.
42. What is a Sand bar?
Sand bar is an elongated deposition of sand or mud found in the sea, almost parallel to the coast.
43. Which is the longest Beach?
The first longest beach in the world is the Miami beach in South Florida in U.S.A. The second longest beach in the world is the Marina beach in Chennai.
44. Define Lagoon:
Lagoon is a shallow stretch of water partially or completely separated from the sea. E.g. Chilka lake in Odisha, Pulicat lake in Tamil Nadu and Andhra Pradesh and Vembanad lake.