Transcript PowerPoint

Earth Science
Erosion
What is Erosion?
BREAK IT DOWN
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Erosion is the process that breaks things down.
Erosion is the breakdown of the continents and the land around you.
Erosion of landforms is caused by running water, frozen water, and wind.
In nature, large things are broken down into smaller things.
Boulders become sand.
Mountains are rained on, erode and become hills.
Erosion causes pieces of the mountain to become smaller pieces and go down
the sides of hills.
 Erosion always happens in a downhill direction.
You Can Make Erosion Happen!
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How?????
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Pretend you are hiking in the mountains.
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You pull a rock from the side of the mountain, then throw it down into a
canyon. You are now a part of the erosion of that mountain.
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You have taken a big object (a mountain) and started to make little
objects out of it (a rock).
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When that rock hit the ground, it could have cracked and made some
tiny pieces of rock (sand).
Mass Wasting
Do you ever wonder where rocks and sand go ?
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Things don't just disappear. The masses of dirt and rock are moved to
another form and place. The wasting is the loss of matter in one place.
Mass wasting can happen two ways:
1) mechanical, similar to breaking a rock with a hammer; and
2) chemical, similar to pouring acid on a rock to dissolve it.
Erosion happens at the tops of mountains and under the soil. Water and
chemicals get into the rocks and break them up through those mechanical
and chemical forces. Erosion in one area can actually build up lower areas.
Think about a mountain range and a river. As the mountain erodes, the river
carries sediment downstream towards the ocean. That sediment slowly
builds up and creates new wetlands at the mouth of the river.
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Mechanical Weathering
 Mechanical weathering is the process of breaking big rocks into
little ones.
 This process usually happens near the surface of the planet.
 Temperature also affects the land. The cool nights and hot days
always cause things to expand and contract. That movement can
cause rocks to crack and break apart.
 Roots and plants also push into the rocks and break them apart.
They act like wedges and push the rocks apart. Little animals also
help by burrowing and digging through the ground.
The Landscape Around Us
VASQUEZ ROCKS IS A SANDSTONE ROCK FORMATION
ERODED BY WIND AND WATER. YOU CAN FIND THIS
COLLECTION OF ROCKS BY DRIVING TO AGUA DULCE
(WHICH IS VERY CLOSE TO OUR SCHOOL).
Yosemite Valley is a landform created by
glaciers. (frozen water)
 The glacier’s force is able to gouge out huge chunks of
rock and soil from the earth.
 As the glacier pushes its way through the mountains it
creates U-shaped valleys called moraines.
 Half Dome was once a “full dome”-until a glacier made its
way through it!!!
The Grand Canyon in Arizona is a
landform created by running water erosion
 Our World is always changing .
 Erosion is always taking place.