Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface? Copyright © Houghton Mifflin...
-
Upload
ferdinand-morgan -
Category
Documents
-
view
235 -
download
7
Transcript of Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface? Copyright © Houghton Mifflin...
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Objectives: Compare weathering and erosion. Explain the causes of weathering and erosion. Describe how erosion and deposition change Earth’s
surface.
Vocabulary:• Weathering• Erosion• Deposition• Sediment
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
What Can Break a Boulder?
• The process of rock breaking apart is called weathering.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
What Can Break a Boulder?• Causes:
• gravity, • flowing
water• blowing
sand• living things• wind• rain• chemicals
Copyright © Houghton Mifflin Harcourt Publishing Company
Rocks on the Move
• Weathering is the beginning of a series of changes that often occurs to rocks on Earth’s surface.
• The process of moving weathered rock from one place to another is called erosion.
• Moving water is one of the most common causes of erosion.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Rocks on the Move• Fast-moving water and gravity can cause rocks to move
downhill.
• As the water in a river slows down, it has less energy and cannot move the largest rocks and pebbles.
• The dropping of weathered rock by wind or moving water is known as deposition.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Rocks on the Move• Slow-moving water has less energy than fast-moving
water has. Thus, as water in a river continues to slow down, more bits of weathered rock are dropped.
• Slow-moving water carries only very small pieces of rock, such as sand and silt, called sediment.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Rocks on the Move• What size of sediment drops out first? What size
drops out last?
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Rocks on the Move
• When rivers reach the ocean, they slow down even more and sediment is dropped. Over time, the sediment forms a landform called a delta.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Exit slips Active reading
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Homework brain check
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Exit slip braincheck
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Blowing in the Wind• A landform is a natural land
shape or feature. Weathering and erosion by wind change landforms.
• Wind can carry sediment from place to place. When wind deposits a lot of sand in one area, sand dunes form.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Blowing in the Wind• Wind sweeps up one side of a dune and lifts sand
from its surface. Gravity pulls the sand down the other slope.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Blowing in the Wind• Blowing sediment can also
cause changes to other landforms as particles collide with exposed rock to form interesting shapes.
• For instance, mushroom rocks and arches are formed by water but shaped by the wind. Eventually, gravity pulls these formations down.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Ice Carvings• Huge sheets of ice are called
glaciers and are found in very cold places.
• Gravity pulls glaciers downhill, picking up soil, rocks, and boulders beneath the glacier and pushing boulders against the ground below.
• When the glacier melts, the rock and sediment it carried downhill drop out and form different land features, including hills called moraines.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Ice Carvings• A huge glacier once
covered most of Canada and the northern United States. The ice cut deep grooves that formed the Great Lakes.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Exit slip Active reading
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Exit slip Active reading
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Can Waves Cut Caves?• Moving water causes weathering
and erosion by picking up sediment, which scrapes against the bottom and sides of the riverbed.
• This carves out deep canyons, which are gorges between cliffs of rock.
• Deposits of sediment can change the direction of river water. Curves in a river’s path can produce different landforms.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Can Waves Cut Caves?• Ocean waves weather
cliffs, eroding pieces of rock and depositing them into new places, forming caves in shoreline cliffs.
• The sediment from eroding shorelines becomes fine sand, and beaches are formed at the water’s edge.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Exit slips Active reading
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Homework Braincheck
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Do Plants Protect Soil?• In the early 1900s, families in
the central plains of the United States made a living farming land where natural grasses once grew.
• In between crop seasons, loose soil was left exposed to wind.
• During the 1930s, the plains experienced severe drought. The soil turned to fine, dry dust, and high winds caused giant dust storms.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Do Plants Protect Soil?• These dust storms stripped
away much of the soil that made the region good for farming.
• Families moved away to find other ways to survive. They suffered hard times. The region became known as the Dust Bowl.
• The Dust Bowl teaches a valuable lesson about erosion problems caused by removing all the plants from an area.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Do Plants Protect Soil?• Now farmers plant
different crops at different times to keep soil covered year-round.
• Fences and lines of trees are planted to break the wind, and plants are added to hillsides to protect soil from water erosion and wind.
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?
Copyright © Houghton Mifflin Harcourt Publishing Company
Exit slips Active reading
Unit 8 Lesson 1 How Do Weathering and Erosion Shape Earth’s Surface?