Erosion

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Erosion WeatheringChanges
ErosionWeathering
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Essential Questions

• What is weathering?
• What is erosion?
• What is the difference between slow and fast
  moving changes to the Earths surface?

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What is Weathering?

• WEATHERING is a process that breaks down rocks
  and wears down Earths surface.
• Over time, weathering wears away mountains. Air,
  water, ice and organisms break rocks into smaller
  pieces.

What Is It ?
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What is Erosion?

• Erosion is a destructive force in which pieces of
  rock are moved. EROSION occurs when wind, water,
  or ice move rock and soil.
• Ex. Waves are constantly eroding rocks, sand and
  soil along the coastline.
• Ex. You already know that ice expands as it
  freezes. When water gets into the cracks and
  freezes, the rock expands and later is broken
  down into smaller parts.

What Is It ?
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More About Weathering and Erosion

• Weathering is when
• rocks are broken
• down, like the Grand
• Canyon.

• Erosion can cause
• mudslides.

Mud Slides
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Weathering/Erosion

• Erosion
• can move sediments
• can turn mountains into valleys and form lakes
• can cause sand dunes

• Weathering
• breaks down rocks
• can form caves

Effects
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Icy Rocks

• The freezing and melting of water causes
  weathering. When water freezes, it expands. The
  ice in the cracks of the rock, push against the
  sides of the rock. Then the ice melts.
  Eventually, the rock will split apart.

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Lets See.

• You already have learned that weathering breaks
  down rocks and erosion moves the rocks. Now, lets
  look at fast and slow moving changes.

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Slow Moving Changes

• Earths surface is constantly changing.
  Weathering and Erosion are both considered Slow
  moving changes. One example of slow moving change
  is a sinkhole. It takes a long time for the
  ground to become unstable to sink in. Another
  example of a slow moving change is a canyon.

Slow Fast
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The Grand Canyon

• The Grand Canyon is made primarily of sedimentary
  rocks. Rivers remove rock and soil. Over time,
  they carve out valleys. In some cases, rivers
  carve out deep canyons, such as the Grand Canyon.
  
• You can see the jagged edges of the mountain
  which help us infer that rocks were broken down
  and later carried away.

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The Grand Canyon
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Look at these Sedimentary Rocks- What do you
notice?
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Fast Moving Changes

• One example of a fast moving change is a
  mudslide. Fast changes occur suddenly.
• Volcanoes, earthquakes, hurricanes, and tsunamis
  are also fast moving changes.

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Lets Review

• Which force wears away at Earths surface?
• A. volcanoes
• B. weathering
• C. plates colliding
• D. earthquakes

B.
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Lets Review

• What process is responsible for the creation of
  sea stacks (as seen to the left)?
• A. weathering
• B. deposition
• C. glaciers
• D. erosion

A.
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Lets Review

• Which of the following does NOT cause erosion?
• A. evaporation
• B. wind
• C. ice
• D. water

A.
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Lets Review

• Which process comes first, erosion or weathering?
  
• A erosionB weathering

B.
Weathering breaks down the rocks- Erosion moves
the rocks
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Lets Review

• Water can break down rocks because
• A. water carries strong acids that erode rocks
• B. water takes up less space when it freezes and
  rocks collapse inward
• C. water expands when it freezes in cracks in
  rocks

C.
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Lets Review

• Many sandy beaches are particularly prone to
  erosion as a result of
• A. Tides
• B. Rain
• C. Humans

A.
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Lets ReviewShort Response

• A strong hit from a hammer can help break apart
  rocks. What natural processes can help to weather
  or erode rocks?

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Lets ReviewExtended Response

• Explain how ice can cause the erosion of a rock.
  Draw a diagram if it helps you explain your ideas.

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Lets ReviewShort Response

• Bill invents a device which he says will entirely
  prevent soil erosion near rivers. Tests show that
  it does reduce erosion by 75, but it doesnt
  totally prevent it. Is Bills invention worth
  developing? Give 2 reasons why or why not.