How to Use This Page
This page provides complete exercise solutions for Samacheer Kalvi 7th Social Science — Geography Term 1, Chapter 2: Landforms. Work through each section in order:
1. Read the Key Concepts for a quick recap of the chapter. 2. Attempt each exercise question on your own first. 3. Compare your answers with the detailed solutions below. 4. Review the Common Mistakes section to avoid losing marks. 5. Use the Exam Checklist before your test.
Key Concepts (Quick Recap)
- Landforms are natural features on the Earth's surface shaped by internal (endogenic) and external (exogenic) forces.
- Weathering is the breaking and crumbling of rocks into smaller pieces without any change in their chemical composition.
- Erosion is the wearing away of the landscape by agents like water, wind, ice, and sea waves.
- Deposition is the laying down of eroded material by these agents.
- River landforms: V-shaped valleys, waterfalls, plunge pools, meanders, oxbow lakes, flood plains, levees, alluvial fans, deltas.
- Glacial landforms: Cirques, aretes, U-shaped valleys, moraines, tarn lakes.
- Wind landforms: Mushroom rocks, inselbergs, sand dunes, barchans, loess.
- Coastal landforms: Cliffs, sea caves, sea arches, sea stacks, beaches, lagoons.
- Tributary — a stream that joins the main river; Distributary — a stream that branches off from the main river.
Exercise Solutions
I. Choose the Correct Answer (MCQs)
1. \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is a deposition of river sediments along the foot-hills.
Answer
- a) Plunge pool
- b) Alluvial fan ✓
- c) Flood plain
- d) Delta
ExplanationWhen a river flows from mountains to plains, it deposits sediments in a fan-shaped pattern at the foothills. This is called an alluvial fan.
2. Courtallam falls is located across the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ river.
Answer
- a) Cauvery
- b) Pennar
- c) Chittar ✓
- d) Vaigai
ExplanationCourtallam (Kutralam) Falls, also known as the "Spa of South India," is located on the Chittar River in Tamil Nadu.
3. The landform created by glacial deposition is \_\_\_\_\_\_\_\_\_\_.
Answer
- a) Cirque
- b) Arete
- c) Moraine ✓
- d) Tarn lake
ExplanationMoraines are ridges of rock debris deposited by glaciers. Cirque, arete, and tarn lake are erosional features, while moraine is a depositional feature.
4. Large deposits of loess are found in \_\_\_\_\_\_\_\_\_\_.
Answer
- a) the USA
- b) India
- c) China ✓
- d) Brazil
ExplanationExtensive loess deposits are found in northern China, brought by wind from the Gobi Desert.
5. Landform which is not associated with wave erosion
Answer
- a) Cliffs
- b) Sea arch
- c) Stacks
- d) Beaches ✓
ExplanationBeaches are formed by wave deposition, not erosion. Cliffs, sea arches, and stacks are all erosional features created by sea waves.
II. Fill in the Blanks
1. The process of breaking and crumbling of rocks is weathering.
2. The place where the river joins a lake or a sea is known as river mouth.
3. Inselbergs are found in the Kalahari desert in South Africa.
4. A cirque is known as Kar in Germany.
5. The longest beach in the world is Miami Beach in the U.S.A.
III. Match the Following
| S.No. | Column A | | Column B |
|---|
| 1. | Breaking and crumbling of rocks | → | d) Weathering |
| 2. | Abandoned meander loops | → | e) Oxbow lake |
| 3. | Large body of moving ice | → | a) Glacier |
| 4. | Crescent-shaped sand dunes | → | b) Barchans |
| 5. | Vembanad lake | → | c) Lagoon |
Explanation
- Weathering is the process of breaking rocks into smaller pieces.
- Oxbow lakes are abandoned meander loops cut off from the river.
- Glaciers are large bodies of moving ice.
- Barchans are crescent-shaped sand dunes found in deserts.
- Vembanad Lake in Kerala is a lagoon — a shallow water body partially separated from the sea.
IV. Consider the Following — Tick the Appropriate Answer (Assertion-Reason)
1. Assertion (A): The deltas are formed near the mouth of the river. Reason (R): The velocity of the river becomes slow when it approaches the sea.
Answer
- a) Both A and R are correct ✓
- b) A is correct and R is wrong
- c) A is wrong and R is correct
- d) Both A and R are wrong
ExplanationAs the river approaches the sea, its velocity decreases, causing it to deposit sediments and form a delta. Both statements are correct and R explains why deltas form at the river mouth.
2. Assertion (A): Sea arches in turn become Sea Stacks. Reason (R): Sea Stacks are the results of wave deposition.
Answer
- a) Both A and R are correct
- b) A is correct and R is wrong ✓
- c) A is wrong and R is correct
- d) Both A and R are wrong
ExplanationSea arches do eventually become sea stacks as erosion continues — so A is correct. However, sea stacks are formed by erosion (not deposition) — so R is wrong.
V. Very Short Answers (1–2 sentences)
1. Define erosion.
Answer
Erosion is the wearing away of the landscape by agents such as water, wind, ice, and sea waves. It involves the removal and transportation of rock material from one place to another.
2. What is a plunge pool?
Answer
A plunge pool is a hollow feature at the base of a waterfall, formed by the force of falling water through a process called cavitation.
3. How are Oxbow lakes formed?
Answer
Due to continuous erosion and deposition along the sides of a meander, the meander loop gets cut off from the main river, forming a cut-off lake called an oxbow lake.
4. Name the major landforms formed by glacial erosion.
Answer
The major landforms formed by glacial erosion are: cirque, tarn lake, arete, and U-shaped valley.
5. Give a note on Mushroom rocks.
Answer
In deserts, wind erosion carries rocks into the shape of a mushroom — narrow at the base and wide at the top. These are called mushroom rocks, formed because wind erodes the lower part more than the top.
6. What is a lagoon? Give an example.
Answer
A lagoon is a shallow stretch of water that is partially or completely separated from the sea. Examples: Chilka Lake, Pulicat Lake, and Vembanad Lake.
VI. Short Answers (3–5 sentences)
1. Distinguish between Tributary and Distributary.
Answer
| Feature | Tributary | Distributary |
|---|
| Definition | A stream that flows into and joins the main river | A stream that branches off and flows away from the main river |
| Effect on volume | Increases the volume of the main river | Decreases the volume of the main river |
| Location | Found in the upper and middle course | Found in the lower course, near the delta |
A tributary adds water to the main river, while a distributary takes water away from it.
2. Distinguish between V-shaped valley and U-shaped valley.
Answer
| Feature | V-shaped Valley | U-shaped Valley |
|---|
| Formed by | River erosion | Glacial erosion |
| Shape | Steep sides forming a V | Wide and deep forming a U |
| Process | Vertical erosion by the river | Lateral and vertical erosion by glacier |
| Example | River valleys in mountains | Valleys in the Himalayas and Alps |
3. Distinguish between Continental glacier and Mountain glacier.
Answer
| Feature | Continental Glacier | Mountain Glacier |
|---|
| Definition | Covers vast areas of a continent with thick ice sheets | A stream of ice flowing along a valley bounded by steep sides |
| Size | Very large | Relatively smaller |
| Examples | Antarctica, Greenland | The Himalayas, the Alps |
VII. Detailed Answers (Paragraph-length)
1. Explain different landforms produced by river erosion.
Answer
Running water in a river erodes the landscape and forms several distinctive landforms:
- V-shaped Valley: The river erodes vertically, creating a steep-sided valley shaped like the letter V. This occurs in the upper course of the river where it cuts deep into the ground.
- Waterfall: When soft rocks are removed by river erosion faster than hard rocks, a sudden drop in the river bed is created, forming a waterfall. Example: Courtallam Falls on the Chittar River.
- Plunge Pool: At the base of a waterfall, the force of falling water creates a hollow feature through cavitation. This is called a plunge pool.
- Meanders: As the river flows over gently sloping terrain, it develops large bends called meanders. Continuous erosion on the outer bank and deposition on the inner bank causes these bends to grow.
- Oxbow Lake: When the meander loop becomes very pronounced, the narrow neck of the loop is cut off from the main river, forming a crescent-shaped lake called an oxbow lake.
2. Describe the landforms associated with wind.
Answer
Wind is an active agent of erosion and deposition in desert regions, producing several landforms:
- Mushroom Rocks: In deserts, wind erodes the lower portion of rocks more than the upper portion, giving them a mushroom-like shape with a narrow base and wide top.
- Inselbergs: These are isolated residual hills standing like pillars with rounded tops, formed by prolonged wind erosion that removes the surrounding softer rock.
- Sand Dunes: When wind transports and deposits sand, it accumulates in low hill-like structures called sand dunes. They are common in desert regions.
- Barchans: These are crescent-shaped sand dunes with a gentle slope on the windward side and a steep slope on the leeward side.
- Loess: Very fine and light sand transported by wind is deposited over large areas as loess. The most extensive loess deposits are found in China, brought from the Gobi Desert.
3. How are aretes formed?
Answer
Aretes are narrow, steep-sided ridges formed by glacial erosion. When two adjacent cirques (bowl-shaped hollows carved by glaciers) erode towards each other from opposite sides of a mountain, the previously rounded landscape is gradually transformed into a narrow, rocky, steep-sided ridge between the two cirques. This ridge is called an arete. The continuous back-to-back erosion by glaciers on either side deepens the cirques and sharpens the ridge, producing the characteristic knife-edge shape of an arete.
Additional Important Questions — MCQs
1. The place of the origin of the river is Source (a).
2. The highest waterfalls in South America is Angel (c).
3. \_\_\_\_\_\_\_\_\_ falls is located on the border between Canada and U.S.A. — Niagara (b).
4. Victoria Falls is located in Africa (d).
5. Meander River flows in Asia Minor (d).
6. Corrie cirque is located in Scotland (b).
7. The crescent-shaped sand dunes are called Barchans (a).
8. The collection of sediments from all the mouths of a river forms a Delta (b).
9. The largest beach in the world is Miami (d).
10. A shallow stretch of water partially separated from the sea is a Lagoon (a).
Additional Important Questions — Fill in the Blanks
1. Rivers generally originate from a mountain or hill.
2. The raised river banks are called Levees.
3. An active agent of erosion and deposition in the deserts is wind.
4. An isolated residual hill standing like a pillar with rounded tops is an Inselberg.
5. Northern China loess deposits are brought from the Gobi Desert.
6. A part of land adjoining near the sea is called sea coast.
7. The boundary of the sea coast, where land meets water, is coastline.
8. Sea cliffs are steep rock faces formed when sea waves dash against them.
9. The wall-like feature in the sea is stacks.
10. The second largest beach in the world is the Marina beach in Chennai.
11. Moraines are glacial deposition.
12. A stream or river that flows into and joins the main river is a Tributary.
13. The collection of sediments from all the mouths of a river forms a Delta.
Common Mistakes
1. Confusing erosion and weathering: Weathering breaks rocks in place; erosion carries the broken material away. Both are different processes. 2. Confusing moraines with cirques: Moraines are depositional features (piles of debris), while cirques are erosional features (bowl-shaped hollows). 3. Saying beaches are formed by erosion: Beaches are depositional features formed by wave deposition, not erosion. 4. Confusing tributary and distributary: A tributary adds water to the main river; a distributary takes water away. 5. Mixing up V-shaped and U-shaped valleys: V-shaped valleys are formed by rivers; U-shaped valleys are formed by glaciers. 6. Confusing alluvial fan with delta: Alluvial fans form at foothills where a river enters plains; deltas form at the river mouth where it meets the sea. 7. Forgetting that loess is a wind-deposited feature: Loess is fine sediment deposited by wind, not water.
Exam Checklist
- [ ] Can you define weathering, erosion, and deposition clearly?
- [ ] Can you list at least 3 landforms each formed by rivers, glaciers, wind, and sea waves?
- [ ] Can you distinguish between V-shaped and U-shaped valleys?
- [ ] Can you explain how oxbow lakes are formed?
- [ ] Do you know the difference between tributary and distributary?
- [ ] Can you match landforms to their formative agents (river, glacier, wind, sea)?
- [ ] Can you explain mushroom rocks, barchans, and loess?
- [ ] Can you name examples: Courtallam Falls (Chittar River), Miami Beach, Kalahari Desert, Gobi Desert?
- [ ] Do you remember that alluvial fans are at foothills and deltas are at the river mouth?
- [ ] Can you answer assertion-reason questions by checking both statements independently?
