Weathering

Weathering The process of breaking down rock by other substances at

Earth’s surfaceErosion

The carrying weathered rock from one location to another

Mechanical WeatheringRock is physically broken downSmaller pieces have same composition

Chemical WeatheringRock is chemically broken downSmaller pieces have different composition

Weathering

Release of PressureTopsoil is removedRock allowed to expand and flake off

Mechanical Weathering types

Freezing and ThawingWater enters crack in rockWater freezes and expands

crack in rock

Mechanical Weathering types

Plant GrowthPlant roots grow in cracks of rockAs roots grow and expand cracks are widened

Mechanical Weathering types

Animal ActionAnimals (moles, groundhogs, and

some insects) dig into groundSoil is then loosened

Mechanical Weathering types

AbrasionSand and other rock particles

are carried by water, wind, and ice

Rock is then worn away like sand blasting

Mechanical Weathering types

Chemical WeatheringRock is chemically broken downSmaller pieces have different composition

Factors for rate of Chemical WeatheringClimateType of rockAmount of surface area

Chemical Weathering

WaterMost important

causeDissolves rockMaterial (Rock)

mixes uniformly in water to make a solution

Chemical Weathering types

OxygenOxidation: Oxygen mixes with

metal (Iron) Product is rustRock that has iron in it oxidizes

or rustRust causes rock to become soft

and crumble

Chemical Weathering types

Carbon DioxideAtmospheric gasMixes with rainwater and

groundwaterWater seeps into cracks and pours of

rocksEasily weathers limestone and

marble

Chemical Weathering types

Chemical Weathering typesLiving Organisms

Plants that grow on or in rocks produce a weak acid that chemically break down rockExample: Lichens and mosses

Acid RainBurning fossil fuels (oil, coal, and gasoline) Byproduct produces gases (sulfur, carbon, and

nitrogen) compounds producedCompounds combine with water vapor in

clouds forming acids (carbonic acid)Raindrops fall as acid rain causing rapid

chemical weathering

Chemical Weathering types

Chemical WeatheringAcid Rain

Chemical WeatheringAcid Rain

Chemical WeatheringAcid Rain

How does weathering affect rock?Independent variable:Dependent variable:Things that remain constant:

PredictionMaterials

Sugar Cube Lab

ProcedurePlace one sugar cube in each cupCrush one of the sugar cubesMeasure out ______ml of water in each

graduated cylinderPlace water in cup with sugarTime how long sugar takes to dissolve in

solution while stirring.

Sugar Cube Lab

Data Table:

Graph:

Conclusion:What happen to the sugar cubes (use numbers to

support)Why did this happenWhat does the crushed sugar cube representWas there a possibility for any errors

Sugar Cube Lab

Written response paragraphHow does surface area affect the rate the rock

is weathered

Sugar Cube Lab