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Weathering and Erosion

An investigation and presentation on weathering and erosion.


on 24 September 2012

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Transcript of Weathering and Erosion

An Investigation and Presentation Weathering and Erosion SIMILARITIES They are two processes that together produce natural marvels. They are accountable for the formation of caves, valleys, sand dunes and other naturally formed structures. Erosion needs weathering to occur. The two processes are often getting mixed up as they work very close together. They both act to remove materials such as rocks, soil or minerals either by chemical breakdown or physical movement. They both work together to shape mountains, valleys, plains and other features. DIFFERENCES They are two separate processes. Weathering is the process of breaking down of rocks while erosion is the process where sediments are moved away from the original location. Weathering may be caused by the action of water, air, chemicals, plants or animals while erosion may be caused by rain or irrigation. How does weathering and erosion affect people? There is no movement in weathering but there is movement of eroding agents in erosion. Weathering will cause rocks to break down into smaller particles but stays where it was. However, after erosion takes place, the resulting smaller particle is transported or moved to another place. Erosion causes rocks to break down into smaller pieces compared to weathering. PHYSICAL WEATHERING It is the disintegration of rock into smaller pieces. It is often caused by atmospheric changes such as heat or freezing temperatures. When water freezes and expands in crevices, it causes rocks to crack which results in frost wedging. Extreme temperatures changes such as rapid heating and cooling can also cause rock to expand and contract. Wind is a force that causes abrasive weathering by blowing sand against rock faces. CHEMICAL WEATHERING It is the disintegration of rock caused by chemical alteration of the mineral structure. The main cause of chemical weathering is the presence of weak acids in water coming in contact with rock. Another agent of chemical weathering is acid rain caused by pollution such as factory and car exhaust. Chemical weathering also occurs when iron in rock oxidizes or rusts. In addition, certain types of lichens and fungi growing on rock secrete acids that etch stone surfaces. WATER EROSION Heavy rainfall and flooding can wash soil, rock and sediments away into rivers and streams. Water erosion reshapes shorelines and deposits soil in new locations. Materials can be swept away by the water's force or dissolved in the water and washed away. In addition, when organic materials, which helps retain soil structures, is washed from topsoil, the soil becomes more prone to erosion. WIND EROSION It is a powerful erosive force, especially when soil is depleted and dry. Sand and soil are swept up and carried away in clouds of dust. GRAVITY Gravity is another force that contributes to erosion, especially when combined with slopes. It pulls rocks and boulders down mountainsides and chunks of ice down glaciers. Gravitational pull also helps move water laden with dirt and weathered materials to low-lying areas. When erosion occurs on a large scale such as a landslide, it can result in devastation of communities, roads, land and even lead to loss of life. Loss of topsoil can render the soil much less fertile for farming. Habitats could be lost. Beaches may become steeper and causes them to be less attractive. Frost wedging can fracture and crack pavements and roadways making it hard for vehicles to move around. Erosion Weathering Positive impacts Weathering breaks rocks down into soil and dirt. Without these soil to grow our crops, it will be impossible to feed the human population. Weathered limestone is also used in many cement and steel industries. Negative impacts. Limestone is used in building construction. However, due to weathering, it has caused damage to buildings. Land used for farming are fundamentally affected due to the weathering of the bedrock. This damages the soil we use to grow crops for consumption. Done by: Bernadette Yeo (38)
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Janelle Sim (14)
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Cherie Chow (4)
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Joey Ng (24)
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