WeatheringWeathering

Natural decomposition of Natural decomposition of rocksrocks

Evidence of WeatheringEvidence of Weathering

Broken sidewalksBroken sidewalks Discolored rocksDiscolored rocks RustRust Disintegrating statuesDisintegrating statues Sandy beachesSandy beaches CavesCaves SoilSoil

Mechanical Mechanical WeatheringWeathering

Breaks down rocks in size Breaks down rocks in size onlyonly. There is no change in . There is no change in composition of the rocks.composition of the rocks.

1. Frost Action1. Frost Action

Water freezes and expands in the cracks of rocks, breaking them apart.

Also called Ice Wedging.

2. Root Pry2. Root Pry

Tree roots grow in cracks of rocks, breaking them apart.

3. Salt Crystals3. Salt CrystalsThe growth of salt crystals in dry climate can break apart rocks.

4. Exfoliation4. Exfoliation

Rocks will break off in layers due to a decrease in pressure or temp. change.

5. Burrows5. Burrows

Earthworms help break down the rocks when air and water enter their burrows.

Chemical WeatheringChemical Weathering

A process that changes the A process that changes the chemical composition while chemical composition while

reducing it to smaller reducing it to smaller fragments.fragments.

1. Carbonation1. Carbonation Carbonic acid Carbonic acid

forms from forms from water and water and carbon dioxide carbon dioxide mixing and can mixing and can dissolve feldspar dissolve feldspar and calcite and calcite found in rocksfound in rocks..

CO2 + H2O = H2CO3

2. Oxidation2. Oxidation Water and oxygen combine with iron in the rock Water and oxygen combine with iron in the rock

to form iron oxide (rust).to form iron oxide (rust).

Other metals can also be oxidized.Other metals can also be oxidized.

Magnesium OxideMagnesium Oxide

3. Hydration3. Hydration

Water dissolves minerals in rock and Carries them away.

4. Plant Acids, such asLichens also dissolve Rocks.

Organic WeatheringOrganic Weathering

When living When living things help things help break down break down rocks.rocks.

Root pryRoot pry

BurrowsBurrows

Plant acidsPlant acids

Factors Affecting Rate Factors Affecting Rate of Weatheringof Weathering

Increase in temperatureIncrease in temperature Amount of rainfallAmount of rainfall Freezing and thawing conditionsFreezing and thawing conditions Topography (lay of the land)Topography (lay of the land) Altitude Altitude Composition of rocksComposition of rocks