EROSIONEROSION

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Weathering, Erosion, Deposition, and Landscapes

Weathering – the breakdown of rocks into smaller pieces, called sediments.

Erosion – the process where the sediments are transported by wind, gravity, glaciers, and running water.

Deposition – the process whereby these sediments are dropped by their transporting agents.Weathering breaks down the rocks, erosion moves the particles, and deposition drops the sediments in another location.

Erosion: Gravity is the

main force causing erosion

Deposition: Can be moved by

wind or flowing water

Weathering Χ Can be physical or chemicalΧ Has to happen before erosion. The rocks have to be broken into smaller pieces before they can erode away.

1. Release of Pressure2. Freezing & Thawing3. Animal Actions4. Plant Growth

Root/Plant Wedging/Action

Ice/Frost Wedging/Action

Rusting Action

WEATHERING

Release of PressureΧ As the surface of a rock is eroded, the rock begins to release pressure.Χ Causes top layers of the rock to crack and flake off.

Freezing & Thawing

When water in the cracks of rocks freezes it expands causing the crack to enlarge or get bigger. The ice melts & refreezes over & over, breaking the rock apart.

Animals dig (burrow) through the ground to make their homes. This loosens the soil & breaks apart rocks.

Plants roots can grow into cracks in the rock, slowly breaking them apart.

Moving water causes much of the erosion that shapes the Earth’s surface

Sediments that have been transported through running water appear rounded and smooth and are deposited in sorted piles.

Water can deposit materials in other places to create new landforms.

Sediments are deposited in sorted piles.

Can loosen sediments and carry them away

Can cause flooding Damages soil,

roads, and buildings

Cause erosion along coastlines

Sand in the waves acts like sandpaper Weathers away

rock Grasses and

plants can help hold soil in place

Gravity pulls glaciers down along a valley

Grind rocks beneath them into sediments

Over a long time, creates a U shaped valley

Gravity causes rivers to flow

Carry sediments Rock, sand, and soil

Deposited materials found at the bottom of cliffs or steep slopes

Can form deltas Appear angular

and unsorted.

Caused by wind blowing dust, soil, or sand from one place to another

Sediments appear pitted (random holes) and frosted (glazed look) and are deposited in sorted piles

Only very small particles can be transported by wind.

Changes sand dunes and fields

Sediments are deposited in sorted piles.

Large, loose deposits of sand

Size and shape depend on speed and direction that winds are blowing

More common in drier landscapes Easier for particles

to move through the air

Less plant life to hold down soil

Bare, plowed fields can become dry

Winds blow topsoil off fields

Farmers plant trees along edges of fields to stop wind

Less they plow, less erosion