Weathering is the process of breaking rocks apart through various natural forces, while erosion involves the movement of these weathered materials, primarily by water. As rivers slow down, they deposit sediment, forming landforms like deltas, while wind can create features such as sand dunes and shape existing rocks. Together, weathering and erosion significantly alter the Earth's surface.

1. Unit 8 Lesson 1 How Do Weathering and Erosion
Shape Earth’s Surface?
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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.
• Many things cause weathering, such as gravity,
flowing water, blowing sand, living things, wind,
rain, and chemicals.

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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?

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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?

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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.
• 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?

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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?

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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?

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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?

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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?