Earth and Space Science / Unit 5: Weathering, Erosion and Earth's History
5.3 Erosion and Deposition by Water, Wind and Gravity
Notes
Erosion moves weathered material; deposition drops it.
- Running water is the most important agent. Fast water carries bigger particles. Rivers make deltas where they slow at the sea and alluvial fans where they leave mountains.
- Wind moves sand by saltation (bouncing) and makes dunes; deflation removes fine particles.
- Gravity causes mass movement: landslides, rockfalls, creep.
- Sediment gets sorted: slower water deposits larger, heavier grains first.
Practice
A delta forms where a river:
Slowing water drops its load.
Which agent of erosion creates sand dunes?
Wind piles sand into dunes.
As a stream slows down, which particles are deposited first?
Larger, heavier particles need more energy to move.
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