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science-changing earth's surface

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Marta Pastori

on 3 May 2013

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Transcript of science-changing earth's surface

by Marta Pastori Weathe Mechanical Weathering chemical weathering erosion chemical weathering is when the rock is weakened by chemical reactions and composition erosion is when sediment is transported from one place to another Changing Earth's surface

weathering, erosion and deposition work in a cycle. weathering breaks the rock apart into sediment, erosion brings it to another place, and deposition deposits it at the bottom of a lake or river. weathering, erosion, and deposition weathering is the part of the process when rock is broken down into smaller pieces energy Energy is the ability to do work or cause change.
rivers carry energy.
there are 2 kinds of energy:
Potential energy is energy that is stored and waiting to be used later
Kinetic energy is the energy an object has due to its motion

gravity pulls water down a slope, and the water’s energy (Potential) changes to kinetic energy that can do work weathering has two major types, mechanical weathering and chemical weathering freezing and thawing water goes into a crack and freezes
it increases mass, so it makes the crack bigger
the water melts
it goes deeper into the crack and then
it freezes again
this cycle of ice wedging keeps repeating Mechanical weathering is when the rock is broken physically in smaller pieces. There are five types of mechanical weathering, freezing and thawing, realize of pressure, plant growth, actions of animals, and abrasion. release of pressure Erosion removes material from the surface of a rock,
the pressure on the rock is reduced.
This release of pressure causes the outside of the rock to crack and flake off Plant Growth This happens when a plant grows inside a rock. The plant’s roots break it up into smaller pieces Animal Action Some animals break rocks down by digging through rock; they loosen it and break it apart. Abrasion Sand and little pieces of rock are carried by wind, water, or ice can wear away exposed rock. there are five different types of chemical weathering, water, oxygen, carbon dioxide, living organisms, and acid rain water Water can dissolve minerals in rocks and make the rocks weaker oxygen When there is oxygen in the air, it erodes iron and makes it rusty carbon dioxide The carbon dioxide dissolves in rainwater, and turns into an acid. When it falls to the ground, it easily erodes rock living things If plant grows in rock, its roots both break it apart and release some acids that erode rock acid rain Pollution in the air can turn the rainwater into acid that breaks down rock and changes its components soil sediment comes in different sizes, clay, silt, and sand
•Second largest particle of soil
•Coarse and of soil
•Coarse texture Clay:
•Smallest particles (like flour)
•Smooth and silky
•Heavy, dense texture
•Holds lots of water Silt
•In size, bigger than clay, but smaller than sand
•Solid dust, like sediment
•Forms when rock is eroded erosion includes energy, mass movement, runoff and rivers Mass Movement mass movement is when a big chunk of land moves there are different types of mass movement,
Landslides, Mudflows, Slump, and Creep landslides landslides move fast and usually happen on steep slopes. They are the most dangerous kind of mass movement.
Some landslides contain huge masses of rock, starting with a little, the amount increasing as the landslide rolls down the slope Mudflow mudflows contain rock, sediment, soil, and up to 60% water. they slide down steep slopes, usually in dry areas rapidly.
In clay soils with a high water content, mudflows may also happen on gentle slopes. slump Slumps happen when a mass of rock and soil suddenly slips down a slope
material in a slump moves down in one large mass
It looks as if someone pulled the bottom out from under part of the slope
A slumps happen when water soaks the bottom of soil that is rich in clay Creep creep mass movement happens very slowly and might happen on gentle slopes. It is mostly caused by freezing and thawing under the ground.
Creep may tilt these objects at spooky angles Gravity, running water, glaciers, waves and wind are all causes, or agents, of erosion How fast does a river flow? the faster a river flows, the more it weathers and erodes, and the less it deposits. how fast a river flows depends on the slope, the amount of friction, amount of sediment it carries, and volume of the flow Slope a river running down a steep slope travels less distance, because gravity will pull it down the shortest and fastest way it can, but it does not mean it will take less time than a gentle slope because there are other factors that contribute to a river's speed. friction rocks at the bottom of a river slow the river down because of friction.
friction is when two things or forces push in different directions. if a river is deep and narrow it will flow faster because it has less area effected by friction than a shallow and wide one. sediment load the sediment load is the amount of sediment a river carries. this is another factor that effects the speed of a river. volume of the flow the volume of the flow is how much water a river contains. the more water, the faster the water travels tributary erosion by rivers water is one of the greatest agents of erosion. it causes:
•oxbow lake
•Groundwater Erosion and
•Cave formations
•Karst topography waterfalls Waterfalls happen when there is a harder layer of rock than the one surrounding it and the water just flows over that area and weathers other rock, making a cliff, which is filled with water and forms a waterfall floodplain A flood plain happens when a river flows through a gently sloping land, spreads out, and erodes the area around itself, creating a large valley. meander A meander is a curve in a river made of very weak rock that is easy for the water to erode. This allows the water to erode the rock on the outside of the curve and deposit on the inside, making the river flow in a larger curve. oxbow lake An oxbow lake happens when a meander makes a large loop on a side of the river. Eventually, water will dig straight and make a loop apart from it. then it will start flowing straight , without going through the loop, and deposits sediment on the side of the loop, causing it to close off and form a C-looking lake. groundwater erosion groundwater is the term for water found underground
groundwater is water that, after rain does not evaporate or become runoff, but sinks into the ground. this water shapes underground rock just like water on the surface does, but underground Caves formations in caves, water with carbonic acid and calcium deposit, forming stalactites and stalagmites. stalagmites come up from the ground and stalactites go down from the ceiling. these formations form over millions of millions of years drop by drop dripping from the roof and depositing partly at the bottom of the stalactite and at the top of the stalagmite right beneath it. Karst topography rainy areas where there is a layer of limestone near the surface
groundwater erosion can significantly change the shape of the land
there are very little streams, because water easily sinks down ground
there are lots of valleys wind erosion wind is a minor agent of erosion and erodes way less than water. wind erosion includes deflation and abrasion deflation deflation is the force that carries soil through air.
picks up mostly clay and silt.
Sand can bounce for a short distance but then falls again
•Sometimes deflation creates an area of rock fragments. Wind blows away all the small pieces and only gravel and heavier pieces are left abrasion •Abrasion is the force of wind that carries sediment, which rubs against rock and weathers it
•Abrasion changes slightly the shape of a rock, smooths and polishes it

When a river flows out of a steep mountain side, it becomes shallower and wider and slows down, it deposits sediment and other rock particles in a pile, in the shape of a fan, forming an alluvial fan Deposition deposition is the process when sediment is layered at the bottom of a lake or river
•Alluvial fans
•Soil on Flood Plains •Wind Deposition
•sand dunes
•loess deposits deposition includes: alluvial fans
A delta happens where a river is flowing on a flat ground into a lake or ocean. It slows down and deposits sediment, making small piles. Deltas can be in lots of shapes, usually triangle or arc shaped.

Floods can cause deposition. When a flood retreats, it leaves sediment where the water went, outside the river. This makes the ground fertile and perfect for crops and forests to grow. soil on flood plains wind deposition when wind slows down, or finds an obstacle it deposits the soil it's carrying sand dunes

•When wind strikes an obstacle the result is usually a sand dune
•Sand dunes can come in different shapes and sizes
•Sand dunes move over time
•If plants grow on a dune, they will keep the dune in that place longer
leoss deposits •Silt and clay get carried by the wind to places far from their source. When they get deposited, these places are called leoss deposits. Special thanks to Ms. Tarabelli
for teaching us all these wonderful things
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