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Untitled Prezi

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Rena Iwanaga

on 29 April 2013

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Changing Earth's
Surface By Rena Iwanaga Erosion Deposition Deposition Deposits by Rivers Wind Deposition Wind Erosion Water Erosion Groudwater Erosion Erosion Chemical Weathering Mechanical Weathering Weathering Mechanical weathering is one of the two types of weathering. This type of weathering weathers down rocks physically. This means that it is not caused directly. This includes: freezing and thawing, release of pressure, animal's movement, growing of plants, or abrasion. This type of weathering weathers down Earth's surface mostly with water and temperature. The main cause of this is rainwater, but other types include: actions of water, oxygen, carbon dioxide, living organisms, and acid rain. Erosion is the process that carries
weathered sediment, which include rock, soil, plants and animals. Different types of agents include: mudflow, gravity, running water, glaciers, waves, and wind. The causes of erosion are called, 'agents'. Water is the main and strongest agent of erosion. It begins with raindrops. Water carries sediment as it flows on the ground. When water flows or moves on the ground, it is called a runoff. Some water from rain, not only turns out to form a runoff, but can soak into the tiny cracks on the ground. These water underground are called, Groudwater Erosion, because it can also cause erosion with chamical weathering. Wind Erosion is the weakest agent of erosion. However, it can also cause a lot of erosion. Wind erosion is formed by two sources, deflation and abrasion. Deposition is the process of which sediment is laid in a new place, changing the shape of the Earth. When a river's speed slows down, it drops some of the sediment on a river's bed that it was carrying with it. Deposition by rivers can do two things. It can form deltas and alluvial fans, or it can add sediment to a river's floodplain. The way that wind deposits is similar to the way water deposits. The wind slows down, letting small particles fall and deposite the Earth. This process creates landforms such as sand dunes and loess deposits. Weathering Weathering is a natural process that wears off Earth's surface. This process can break down rocks into pieces, or shape rocks. Geologists know that this process has shaped the Earth from many years ago, based on uniformitarianism. This type of process is one of the mechanical weathering. Water seeps into cracks of rocks, freezes and expands, and with its pressure, it cracks the rock even more. Plant Growth Freezing and Thawing When seeds get into a crack of rock, eventually, a plant or even a tree is going to grow in it. When it grows, it cracks the rock because of the roots sprouting out. Actions of Animals When animals burrow and make holes in soil, they often slip or move rocks off from above, and the rocks fall onto the surface, cracking. Release of Pressure When a mass of rock collects pressure in it, the gradual release of pressure causes the rock to crack, from the outer layer. Abrasion Abrasion is the weathering when rocks rub against rocks that is carried by wind, water, ice or gravity. You often see this at the sea, when the wave pushes rocks, making them rub against other rocks. Actions of Water Water weathers down rocks by dissolving it, particularly limestone. It occurs usually when it rains, with runoff. Oxygen Iron mixed with oxygen and water, forming oxidation. Oxidation is the scientific word for rust. This makes rocks soften, and easy to break, giving it a brick color. Carbon Dioxide This gas forms an acid called carbonic acid, when carbon dioxide mixes with rainwater. The acid created is weak, but easily weathers down rocks such as limestone and marble. Living Organisms Plants dissolve rock when they are growing with weak acids. Living organisms naturally produce acids, that weathers rock. Acid Rain Acids that is formed when compounds from burnt coil, oil and gas respond chemically with water vapor, combine with raindrops, forming acid rain. This type of rain causes weathering of rocks. Rate of Weathering Geologists can determine how fast a rock weathers, with two factors: type and temperature. Type of Rock Permeable rocks weathers fast. These rocks are made of tiny spaces, allowing water to seep through little gaps. Climate Weathering occurs fastest in hot and wet climates. h Gravity & Mass Movement Gravity= power that pushes sediment to go downhill.
Mass movement is caused by this power.
Mass movements include: landslides, creeps, slumps, and mudflows. Landslides A landslide is when sediment falls down a steep slope very quickly. It causes so much harm and damage. Creeps A creep is when sediment falls down a hill, slowly. Freezing and thawing of water usually causes these movements. Slumps This mass movement occurs when a mass of rock and soil drops down a hill altogether. Usually this takes place when the bottom of the soil gets wet. Mudflow This mass movement occurs when a mass of water, rock and soil falls rapidly. It is much like a landslide, except that landslides don't contain water in it. It takes place in dry areas, after it rains. Sometimes, this kind of movement can be very harmful. Rills & Gullies Rills form when runoff creates channel. A gully forms when many rills gather together. A gully is a long and big channel. Gullies can only hold water in them after it rains. Streams and Rivers A stream is a bigger and wider version of a gully. Gullies gather up together to form a stream. Streams are mostly wet with water in them. A large stream is called a river. Tributaries Streams grow into a larger channel, a river by getting more water from tributaries. A tributary is a stream that grows into a bigger river. Erosion by Rivers When rivers flow, it does the process of erosion. As it erodes, they form different types of land such as: valleys, waterfalls, floodplains, meanders, and oxbow lakes. Valleys As rivers erode, it forms a V shaped hallow between mountains, called Valleys. Clay The type of rock called, 'clay' is the smallest particles of soil. It is smooth, but when it holds a lot of water, it is dense and heavy. Silt The particles in a silt are larger than the particles of clay. Sand The type of soil called, 'sand' has the second largest particles after gravel. It has a rough feel, and because it is rough, it is easy for water to seep through it. Potential Energy & Kinetic Energy When rivers flow down a slope, it produces two different kinds of energy. When it a river stores energy to be used, it forms Potential Energy. When it is flowing, it forms Kinetic Energy. Slopes A slope is a hill or an angle of a mountain or a hill. Usually, rivers or streams flow through it. Sediment Load Sediment Load is the amount of sediment a river contains. Volume of Flow The volume of flow is the amount of water a river contains in a certain amount of time. The speed of flow increases as the river carries more water. The Shape of Streambeds The shape of a streambed largely affects the amount of friction. Friction is the force that pushes the motion of water from the opposite way. This affects the speed of a river's flow. Waterfalls Waterfalls are another landform that is formed when rivers flow from the mountain. Waterfalls are formed when a river flows down a hard rock. Floodplains When a river comes near to the bottom, the slopes become gentle, and spreads out, eroding land. It forms a wide valley. This is called a floodplain. Meanders When a river flows in a different direction, in a wavy line, it is called meanders. This is when a river goes off coast. Oxbow Lakes An oxbow lake is a meander that has been separated from a river. Cave Formations When a calcite deposit hangs from the roof of a cave, it is called, a stalactite. A calcite deposit forms when carbonic acid mixes with limestone. A stalagmite is similar to a stalactite, but it is cone-shaped and instead of hanging from the top of a cave, it grows from the bottom of the cave. Karst Topography Karst Topography is when a cave falls down, making holes called a sinkhole. Deflation Deflation is the process of which wind carries materials from the surface with it. Little particles are often easiest for wind to pick up. Of course, if the wind was strong, it would also pick up larger pieces with it too. Abrasion Abrasion usually makes rocks cleaner, than it erodes them. Deltas Landforms such as deltas form where sediment is deposited where a river grows into a larger body of water. These deltas can be different shapes. Soil on Floodplains When deposition occurs during a flood, water spreads across its floodplain. Soon, it deposits new soil. This is called soil on floodplains. Sand Dunes Sand dunes are caused by wind. They can be in different sizes and shapes. Gradually, because of the wind, it shifts along, moving from side to side. The direction of the dunes depend on which way the wind blows. On some dunes, even plants grow on it! Loess Deposits When clay and silt are deposited in layers, it is called loess deposits.These are a great source when it comes to farming.
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