Chapter - 4

BY THE HANDS OF THE NATURE

1. What are the various landf

orms on earth.

◻️The mountains, valleys, plains, plateaus, waterfalls, etc.

2. What are geomorphic processes?

◻️The processes that help in the formation of landforms are called geomorphic processes. 

3. What are geomorphic agents? Write examples.

◻️Varied landforms are created by the continuous processes carried out by external agencies these agencies are often called geomorphic agents.

👉 Running water, wind, glaciers, sea waves, etc.

4. What is the difference between erosion and deposition?

👍🏻 The transfer of rock particles from one place to another by external agencies such as running water, wind, glaciers, sea waves, etc. is called erosion. 

👍🏻 The materials carried by external agencies will be deposited in low lying regions and this process is called deposition. 

5. Name the factors that determine the flow of a river.

◻️Volume of water,

◻️ Rock structure,

◻️ Slope of the terrain, 

◻️Amount of sediments

[10/12, 11:02 pm] Athul Kamukumchery: 6. How V-shaped valleys are formed?

The valleys take a distinct shape as a result of the intensity of erosion along the river bed. Such valleys are called V-shaped valleys.

7. How Waterfalls are formed?

◻️Waterfalls are generally formed at the upper course of rivers as a result of erosion.

◻️Soft rocks are easily eroded in the valleys where soft and hard rocks are found intermingled. This results in the formation of waterfalls.

8. What are meanders?

📚 The sinuous curves formed along the river course are called meanders.

9. How oxbow lakes are formed?

📚 Meanders may further curve through continuous erosion and deposition. Finally the river takes a straight course. 

Due to deposition the curves may get detached from the main river form isolated water bodies. Such water bodies are called oxbow lakes. 

10. What are flood plains?

 Write the importance of flood plains. 

The deposition of alluvium along both the flooded banks may cause the formation of plains.

 Such plains are called flood plains.

[10/12, 11:03 pm] Athul Kamukumchery: 11. Write the features of Karst topography?

Rocks like limestone easily dissolve in rainwater which percolates to form underground water.

The erosional and depositional landforms of underground water are mainly confined to limestone regions. Such landform features are generally called Karst topography.

12. Write short note about landforms created by underground water.

◻️ Limestone caves- Caves formed by the solution of limestone in underground water.

◻️Stalactites-The deposit of lime grows upside down due to long continued depositional process in limestone caves. These are called Stalactites

◻️ Stalagmites :The deposit of lime on the floor of the cave also grows upward as a result of the deposition from above. These are called stalagmites.

◻️ Limestone pillars : Stalactites and stalagmites do merge together with to form pillars.

13. Coastal landforms are created by the erosional and depositional processes carried out by waves. Which are they? How they are formed?

 1)Sea cliffs-The steep hillocks facing the sea are called sea cliffs.

They are formed by the crumbling of the sea-facing slopes due to wave erosion Eg:Varkala beach in Thiruvananthapuram district.

 2)Stacks- Pillar like rocks standing upright along the coastline are called stacks.

The strong blast of sea waves on the rocky coasts causes the wearing down of rocks. As a result of such abrasion by waves, isolated rock pillars are formed from coastal rocks.

 Eg: Stacks found along the coast of Thalassery in Kannur district.

3) Beaches -They are depositional landforms along the coastlines formed with sand, gravel etc.

 Eg: Kovalam, Cherai

[10/12, 11:12 pm] Athul Kamukumchery: 14. What is a glacier?

◻️Slow moving mass of ice is called a glacier.

15. What are cirques?

Arm chair like valleys formed by glacial erosion are called cirques.

16. How U-shaped valleys are formed?

The erosion caused by the continuous movement of glaciers along the valleys carves out steep sided and flat bottomed U-shaped valleys.

17. Name the depositional landform created by glaciers? 

How it will be formed?

📚 Moraines

The sediments carried down by the glaciers will be deposited in various parts of the valley.

 These depositional features by glaciers are called moraines

18. What is the difference between degradation and aggradation?

◻️The elevated regions are levelled down by erosion and low lying regions are filled by deposition. These processes are called degradation and aggradation respectively.

• The processes together are generally called gradation

19. List out the human activities that bring changes to the earth's surface.

◻️Reclamation of agricultural fields.

◻️Deforestation

◻️Mining