Weathering, Erosion and Deposition. Weathering The breakdown do the materials of Earth’s crust into smaller pieces.

Weathering, Erosion and Deposition

Weathering

The breakdown do the materials of Earth’s crust into smaller pieces.

Physical Weathering

• Process by which rocks are broken down into smaller pieces by external conditions.

• Types of Physical weathering– Frost heaving and Frost wedging– Plant roots– Friction and impact– Burrowing of animals– Temperature changes

Frost Wedging

Frost Heaving

Plant Roots

Friction and Repeated Impact

Burrowing of Animals

Temperature Changes

Chemical Weathering

• The process that breaks down rock through chemical changes.

• The agents of chemical weathering– Water– Oxygen– Carbon dioxide– Living organisms– Acid rain

Water

• Water weathers rock by dissolving it

Oxygen• Iron combines with

oxygen in the presence of water in a processes called oxidation

• The product of oxidation is rust

Carbon Dioxide

• CO2 dissolves in rain water and creates carbonic acid

• Carbonic acid easily weathers limestone and marble

Living Organisms

• Lichens that grow on rocks produce weak acids that chemically weather rock

Acid Rain• Compounds from burning coal, oil and gas

react chemically with water forming acids.

• Acid rain causes very rapid chemical weathering

Karst Topography

• A type of landscape in rainy regions where there is limestone near the surface, characterized by caves, sinkholes, and disappearing streams.

• Created by chemical weathering of limestone

Features of Karst: Sinkholes

Features of Karst: Caves

Features of Karst: Disappearing Streams

What Caused This?What Caused This?

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THAT’S RIGHT! EROSION!

Erosion

• The process by which water, ice, wind or gravity moves fragments of rock and soil.

Water Erosion

• Rivers, streams, and runoff

Ice Erosion

• Glaciers

Wind Erosion

Mass Movements

• Landslides, mudslides, slump and creep

landslide clip.mpeg

• Laying down of sediment that has been transported by a medium such as wind, water, or ice – Process of erosion stops:

• when the moving particles fall out of the transporting medium and settle on a surface

– Speed of the medium slows or the resistance of the particles increases, the balance changes and causes deposition

– Speed can be reduced by large rocks, hills, vegetation, etc.

What is What is DepositionDeposition??

Wind speed can be related to variations in Wind speed can be related to variations in heating and cooling.heating and cooling.Transportation of particles in wind:

– Fine particles in suspension hundreds of km from its original source in the desert

– Heavier material may be blown along the ground.– Material is deposited when the wind changes direction or loses its

strength.

DepositionDeposition - Wind - Wind

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• Running water enters a large, fairly still body of Running water enters a large, fairly still body of water and its speed decreases. water and its speed decreases. • SPEED

• As the speed of the water decreases, the water's ability to carry sediment also decreases.

• Deposited in streams, rivers, and oceans:• Running water deposits sediments where the slowing water can

no longer move them.• Largest particles are deposited near the shore. • Increasingly smaller particles settle out farther from the shore

where the water is calmer.

DepositionDeposition - Water - Water

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Delta – a fan shaped deposit that forms at the mouth of a river/stream when it enters a larger body of water like an ocean or lake

Alluvial Fan - a fan shaped deposit of sediments that forms when a stream/river flows out of a mountain on to flat, dry plains. These are not under water and are very visible. This only happens on the land. You can call it a “land delta”.

• Glacial flows of iceGlacial flows of ice – become slower when the ice begins melting

– Deposits left by glaciers:– The deposits of these rivers look similar to normal river deposits and are

called outwashes.– Moraines are large chunks of broken rock left at the base and sides of

the glacier as it melts and recedes.– Finer material is carried in the rivers that form when the glacial ice

melts.

DepositionDeposition - Ice - Ice

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• WEATHERINGWEATHERING – Think of weather wearing rock down.

• EROSIONEROSION – Think of a road and traveling.

• DEPOSITIONDEPOSITION – Think of depositing money into a bank.

What’s the Difference?What’s the Difference?