"Reducing Land Erosion" Earth's Surface and Its Changes PPT Courseware 6

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"Reducing Land Erosion" Earth's Surface and Its Changes PPT Courseware 6

Review and consolidate

1. On the river bed in the upper reaches of the river, we can see that there are many _______, there are many _______ piled up on the middle reaches of the river bed, and there are many _______ piled up on the river bed in the lower reaches.

2. _______ and _______ phenomena occur all the time in nature. _______ caused soil erosion in some raised areas, while _______ filled in some low-lying areas. Because of their effects, different topography and landforms are formed on the earth.

3. Natural forces such as _______, _______, and _______ can also cause erosion and sedimentation on the land.

(1) Glacial erosion

Erosion: During the movement of glaciers, the ice body uproots and carries away the bedrock of the ice bed that is frozen with it.

Abrasion: The rock mass frozen at the bottom or edge of the glacier is in motion, constantly grinding and scraping the bedrock of the valley and both sides like a file, and itself is also being worn away at the same time.

The products of ice erosion: ice erosion valleys, cirques, horn peaks and blade ridges, ice slip surfaces, streak stones, and sheep's back stones.

glacial transport

The glacier freezes the products of erosion and the weathered matter that falls on the ice surface into the ice body, and carries it to the front of the glacier like a conveyor belt, which is called the transport function of the glacier.

Transportation method: pushing and carrying.

glacial accumulation

The accumulation of glaciers occurs when it melts. The accumulation locations are mostly at the front of glaciers below the snow line and at the edge of the continental ice sheet. When glaciers above the snow line partially melt, moraine can also be temporarily accumulated.

The accumulation of glaciers can be divided into two categories: glacier accumulation and ice water and glacial lake accumulation according to the changes in their properties and conditions.

How sand dunes move

The way dunes move depends on the direction of the wind and its changes, and it can be divided into three ways.

One is the forward type, which means it keeps moving in a certain direction all year round under the influence of a single wind direction;

The second is the reciprocating forward type, that is, reciprocating and moving forward when the two wind directions are opposite and the wind force is not equal;

The third is the reciprocating type, that is, it is a reciprocating movement produced when the wind force is equal but the wind direction is opposite.

The movement of the compound sand ridge is realized by the movement of the crescent-shaped dunes and dune chains covering it. According to aerial photos, it is found that the entire compound sand ridge is basically parallel to the synthetic wind direction, or the two are at a small angle. It has an oblique intersecting relationship, and the secondary crescent-shaped dunes and dune chains superimposed on it form an intersection angle of 90° with the entire ridge, and are nearly perpendicular to the wind direction.

Pyramid dunes are a typical dune type affected by multi-directional winds. Although it is an exposed sand dune landform, the dynamic conditions for its formation are the action of multi-directional winds, and the wind force in all directions is relatively balanced, so the dunes swing back and forth, but the total amount of movement is not large.

1. In order to prevent soil loss on the mountain, people adopted ( ) method.

A. Afforestation B. Logging C. Opening up mountains and fields

2. Water and soil loss caused by natural factors in the hilly and gully areas of the Loess Plateau accounts for 9.6%, and water and soil loss caused by human factors accounts for 90.4%.

① Soil and water loss throughout the Loess Plateau ( )

A. Prehistoric times were dominated by natural factors, while modern times are dominated by human factors.

B. Both prehistory and modern times are dominated by natural factors.

C. Both prehistory and modern times are dominated by human factors.

②This text shows that the relationship between humans and soil erosion is ( )

A. Human activities will not cause soil erosion

B. Human activities can cause water and soil erosion, but they cannot control water and soil erosion.

C. Human activities are the main cause of modern water and soil erosion, and humans can also control water and soil erosion.

③The most frequent and serious natural disasters in the Loess Plateau are ( ).

A. Soil erosion B. Acid rain C. Typhoon

3. Which of the following is not caused by soil erosion ( ).

A. Blocking rivers B. Destroying soil fertility C. Forming mountains

1. Water and soil erosion will cause some large plains, so soil and water erosion is not harmful. ( )

2. Soil erosion will aggravate the development of gullies. ( )

3. The water level of the Yellow River is higher than the surface of the earth, which is also caused by soil erosion. ( )

4. Human activities will cause soil erosion ( )

5. Soil erosion cannot be controlled. ( )

6. To reduce the erosion of mountains by rainwater, you can plant trees. ( )

7. In order to make your home withstand the attacks of wind and rain, you can plant more plants around it. ( )

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Update Time: 2024-09-26

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