WeatheringWeathering

DEFINITIONSDEFINITIONSWEATHERING

Brainstorm:

1) What is it?

2) What can cause it?

3) How does weathering change the surface of the Earth?

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Possible Causes:

WEATHERINGWEATHERING

• Weathering= the breaking down of rock into smaller and smaller pieces.

Is weathering constructive, destructive, or both? Why?

-Weathering is destructive- it “tears down” rocks and landforms.

2 Types of Weathering2 Types of WeatheringBrain-storm

1) What can cause each type of weathering?

WEATHERING

1)Mechanical

2) Chemical

Breaking down rocks by physical means

Chemical breakdown of rock and minerals into new substances

Possible causes: Possible causes:

MECHANICAL WEATHERINGMECHANICAL WEATHERING

1. ANIMALSLittle animals also help weathering by burrowing and digging through the ground.

MECHANICAL WEATHERINGMECHANICAL WEATHERING

2. Ice Wedging – when water gets into cracks of a rock, freezes & thaws over & over again & splits the rock

MECHANICAL WEATHERINGMECHANICAL WEATHERING

Ice

MECHANICAL WEATHERINGMECHANICAL WEATHERING

3. PLANT GROWTH• Roots of plants also

push into the rocks and break them apart. They act like wedges and push the rocks apart.

MECHANICAL WEATHERINGMECHANICAL WEATHERING

4. RELEASE OF PRESSURE- as erosion moves sediment from the surface, pressure is reduced. The outside of the rock begins to flake off

MECHANICAL WEATHERING MECHANICAL WEATHERING NONLIVING CAUSESNONLIVING CAUSES

5. Abrasion- sediments carried by wind, water, or ice wear away rock by hitting & scraping against other rock

AbrasionAbrasion

Wind• sandstone shapes

eroded by coastal

winds  Sandblasting

AbrasionAbrasion

WATER - rubs fragments against

each other and wears away the surface of the rock by abrasion.

– The faster the water, the greater the erosion

AbrasionAbrasion

• Ice- Glaciers

–The glacier gouges out chunks of rock and leaves scratches on the rock called striations

CHEMICAL WEATHERINGCHEMICAL WEATHERING

• CHEMICAL WEATHERING the chemical breakdown of rock and minerals into new substances

CHEMICAL WEATHERINGCHEMICAL WEATHERING

Water is considered to be the universal solvent. It dissolves many things – including rock

• Over time, water can break down even hard rock like granite

CHEMICAL WEATHERINGCHEMICAL WEATHERING

2) Oxygen

Oxidation (rust) is a chemical reaction in which an iron combines with oxygen.

CHEMICAL WEATHERINGCHEMICAL WEATHERING

3) Carbon Dioxide (CO2)

-CO2 mixing with water creates Carbonic Acid that slowly dissolves limestone. (Acid in groundwater)-Caves

CHEMICAL WEATHERINGCHEMICAL WEATHERING

4) Living Organisms

Acids from decaying plants or fungi such as lichens breaks down rocks

CHEMICAL WEATHERINGCHEMICAL WEATHERING

is rain or snow that contains more acids than normal due to air pollution.

The acid “dissolves” and “eats away” the rock

5. ACID PRECIPITATION

WEATHERINGWEATHERINGHow does weathering change the surface of the Earth?

Mechanical WeatheringMechanical WeatheringLiving Plant Roots of plants also push into the

rocks and break them apartAnimal burrowing and digging through

the groundNon-living

Ice

(glaciers)

-water gets into cracks of a rock, freezes & thaws over & over again & splits the rock

-scratches on the rock called striationsWind wears away the surface of the rock by

abrasionWater rubs fragments against each other and

wears away the surface of the rock by abrasion.

Chemical WeatheringChemical Weathering

Living Plants Acids from decaying plants or fungi such as lichens breaks down rocks

Non-living

Water universal solvent. It dissolves many things – including rock

Acid rain rain or snow that contains more acids than normal due to air pollution. -acid “dissolves” or “eats away” the rock

Ground-water

CO2 mixing with water creates Carbonic acid that slowly dissolves limestone

Oxidation chemical reaction in which an element combines with oxygen to form an oxide

FORCES THAT CAUSEFORCES THAT CAUSEWeathering

1) Mechanical 2) Chemical

Living Nonliving

Living Nonliving

Plants Ice - (Glaciers)

Plants Water

Acid rain Wind Groundwate

r Animals

Water Oxidation

Interactive WeatheringInteractive Weathering

• How are materials from the earth broken down?