Grade 5 quarter 4 Causes of soil erosion.pptx

Grade 5 quarter 4 Causes of soil erosion.pptx

1. Causes of soil erosion Sit Dolor Amet

2. How Erosion Differs from Weathering? The forces of weathering are responsible for the breaking of rocks. The transport of rock particles elsewhere is continued by another process called erosion .

3. How Erosion Differs from Weathering? While weathering occurs so slowly that it seldom noticed, erosion can be more rapid. The deposition or settling of the finer particles of rock or sediment carried by wind or water can be easily seen.

4. Causes of Erosion Water -Water has force. As water flows, its forces carries rock and soil particles from one place to another. The speed of the flowing water affects the rate of erosion too. The faster the movement of the water, the faster and the farther the erosion would be.

5. Water Faster movement of water indicates a greater force, thus many sediments are carried away by the water.

6. Splash Erosion Raindrops falling on the soil exert pressure with their weight. The force of the wind adds to the force which they strike to the Earth’s surface. This can cause a noticeable movement of the soil.

7. Splash Erosion If the soil loose and is not protected by a covering on the surface, then a large amount of it is lost through raindrops erosion, which is also called splash erosion .

8. Sheet Erosion Water , which does not evaporate or immediately sink into the soil, is called a runoff. During heavy rains, there is more water than what the soil can immediately absorb. Water the flows in broad sheets across a wide area, thus causing sheet erosion.

9. Sheet erosion   is the uniform removal of soil in thin layers by the forces of raindrops and overland flow

10. Wind Erosion The rock particles picked up by the wind are deposited elsewhere, forming hills of sand called sand dunes .This dunes may grow as high as several meters and may also be blown away to other places.

11. Wind Erosion The process of wind carrying away loose sediment is called deflation. Deflation occurs primarily in desert regions. As wind blows along the ground, it scoops up and carries way the loose sediments such as sand and dust.

12. Wind Erosion The process of wind carrying away loose sediment is called deflation. Deflation occurs primarily in desert regions. As wind blows along the ground, it scoops up and carries way the loose sediments such as sand and dust.

13. Erosion by Gravity Bits of rocks are separated and fall down to a lower level of gravity. When gravity moves rock and soil down a slope, it is called mass movement. If broken particles are on a steep slope or at the edge of a cliff, they roll down faster and carry with them other particles on their way. This is why there are piles of rocks at the bases of cliffs and mountains.

14. Erosion by Gravity The whole slope may move slowly downhill without being noticed. A sudden movement is known as landslide . Landslides that occur on the sides of the mountains can destroy entire towns.

15. Glacial Erosion When the amount of snow is so great that it cannot completely melt, glaciers form. As the layers of snow pile up, the weight on the underlying snow increases. Eventually, this weight tightly packs the snow underneath, forming glacial ice. The pressure on the ice at the bottom becomes so great that it partially melts. The entire ice mass starts moving and a glacier is formed.

16. Glacial Erosion As a glacier moves, it causes erosion. The melted water from the glaciers surface or bottom seeps into cracks in rocks and freezes. Ice wedging causes the rock to break apart. The rock fragments stick to the glacial ice and plucked out as glacier moves.

17. Glacial Erosion These pieces of rock stick to the bottom and slides of a glacier act like a sandpaper. As the glacier moves, it scrapes and scratches the bedrock and soil underneath and along its sides. Many landforms result from glacial erosion.

18. Other Factors Causing Erosion Deforestation - clearing of trees, transforming a forest into cleared land.

19. Other Factors Causing Erosion Intensive farming – farmers use excessive fertilizers and irrigation damages the land

20. Other Factors Causing Erosion Housing development and road construction, which makes the soil bare.

21. Choose the letter of your answer. 1. When something erodes, it_____ a. gets magnified b. builds up b. wears away d. enlarges 2. Soil erosion is troubling to farmers because it strips away the _____ that plants like to grow in. a. Deep layers of clay b. topsoil c. Rocks and mud d. water 3 . Which of the following is the definition of erosion? a. The process of disintegration of rock and soil? b. The process that involve the movement of soil and rock c. Both d. None of the above 4. Is erosion a natural process only? a. Yes b. maybe c. No d. none of the above 5. Which process comes first? a. erosion b. weathering c. both

22. Circle the letter that answers the question. 1. When is wind an agent of erosion? a. When it breaks rocks into pieces b. When it carries rock pieces to other places c. When it stops picking up rocks d. When it presses down on rocks. 2. Landslides on mountain slopes show the force of _____ a. gravity b. wind c. runoff d. running water 3. When san dunes are deposited, the agent responsible is ___ a. gravity b. wind c. solution d. raindrops

23. 4. What makes the water muddy after a heavy rain? a. The pebbles picked up by water b. The rainwater turned brown in color c. The gravel and sand carried by the water d. The fine dust particles dissolved in water 5. How can trees help prevent erosion a. The roots hold the soil firmly together b. The trees block the way of running water c. The roots absorb the water at once d. The roots secret acid, attacking the rocks

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