2 weathering, erosion, deposition, and landscapes weathering – the breakdown of rocks into smaller...
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EROSIONEROSION
2
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