Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly? · PDF file•Weathering is the breaking down of rock into ... •Glaciers slide along slowly. ... •As a river flows,...
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Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
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Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
What Weathering Can Do
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• Weathering is the breaking down of rock into smaller pieces.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
What Weathering Can Do
Copyright © Houghton Mifflin Harcourt Publishing Company
• Weathering can happen when tree roots push into the
surface of rock. It can happen when animals burrow into the ground.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
What Weathering Can Do
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• Weathering is often caused by patterns of freezing and thawing.
• First, rain falls into cracks in rock and freezes.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
What Weathering Can Do
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
What Weathering Can Do
Copyright © Houghton Mifflin Harcourt Publishing Company
• As liquid water turns to ice it expands. This widens the cracks.
• When the ice melts, or thaws, the rock is weaker.
• Pieces crumble and fall away. Little by little, the shape of the rock changes.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
What Weathering Can Do
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• Take a look at the picture and imagine how water can cause rocks to crumble and change shape.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
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• Erosion happens when soil, rocks, or sand are moved.
• Wind, water, and glaciers can all cause erosion. It happens everywhere. Wind blows desert sand. Waves wash away beach sand.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
Copyright © Houghton Mifflin Harcourt Publishing Company
• A glacier is a large, thick sheet of moving ice.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
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• Glaciers slide along slowly.
• As they move, many glaciers cut paths through the ground.
• Glaciers also pick up pieces of weathered rock, sand, and soil.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
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• Glaciers push or carry the rocks and soil as they move.
• Sometimes glaciers move enough soil to form a whole island!
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Erosion Motion
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Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Soil Moves Around
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• As a river flows, soil and rocks are swept downstream.
• Now, there is less soil on the riverbanks, and tree roots may be uncovered.
• Plants that need soil may be affected. Without the support of their roots anchored in deep soil, the trees might fall.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Soil Moves Around
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Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Why It Matters Soil Moves Around
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• As soil is washed away from a riverbank it ends up somewhere else.
• As a river nears the ocean, the rocks and soil are dropped.
• This process makes a landform called a delta. A river delta is full of rich soil.
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 5 Lesson 2 How Does Earth’s Surface Change Slowly?
Why It Matters Soil Moves Around
Copyright © Houghton Mifflin Harcourt Publishing Company
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