• Weathering is the process by Weathering is the process by which natural forces break down which natural forces break down rocks.rocks.

• There are 2 types of weathering:There are 2 types of weathering:

1.1. Mechanical weatheringMechanical weathering

2.2. Chemical weatheringChemical weathering

• Mechanical weathering is the Mechanical weathering is the breaking up of rocks by physical breaking up of rocks by physical forces.forces.

• There are 4 main types:There are 4 main types:

1.1. Ice wedgingIce wedging

2.2. ExfoliationExfoliation

3.3. Plant root growthPlant root growth

4.4. AbrasionAbrasion

• When water freezes, it expands. When water freezes, it expands. When water freezes in the cracks When water freezes in the cracks and pores of rocks, the force of its and pores of rocks, the force of its expansion is strong enough to expansion is strong enough to split the rocks apart.split the rocks apart.

• The process in which layers or The process in which layers or sheets of rock gradually break off sheets of rock gradually break off due to the expansion of the rock due to the expansion of the rock caused by a decrease in pressure.caused by a decrease in pressure.

• Trees, bushes, and Trees, bushes, and other plants may take other plants may take root in cracks of rocks. root in cracks of rocks. As the roots of these As the roots of these plants grow, they plants grow, they wedge open the wedge open the cracks.cracks.

• The process of wearing down The process of wearing down by friction, the rubbing of one by friction, the rubbing of one object or surface against object or surface against another.another.

• The breakdown of rocks by The breakdown of rocks by chemical reactions that change chemical reactions that change the rocks’ makeup, or the rocks’ makeup, or composition.composition.

• There are 2 main types:There are 2 main types:

1.1. DissolvingDissolving

2.2. RustingRusting

• Water is the main cause Water is the main cause of chemical weathering.of chemical weathering.

• Many more minerals Many more minerals dissolve in water that is dissolve in water that is slightly acidic – like slightly acidic – like lemonade.lemonade.

• The oxygen in air is also The oxygen in air is also involved in chemical involved in chemical weathering.weathering.

• Many common minerals Many common minerals contain iron. When these contain iron. When these minerals dissolve in water, minerals dissolve in water, oxygen in the air and the water oxygen in the air and the water combines to produce rust.combines to produce rust.

• Most weathering occurs over long Most weathering occurs over long periods of time – hundreds, periods of time – hundreds, thousands, or even millions of thousands, or even millions of years.years.

• There are 3 Influential factors:There are 3 Influential factors:1.1. Surface areaSurface area2.2. Rock compositionRock composition3.3. ClimateClimate

• The more of a rock’s surface that is The more of a rock’s surface that is exposed to air and water, the faster exposed to air and water, the faster the rock will break down.the rock will break down.

• Different kinds of rock break down Different kinds of rock break down at different rates.at different rates.

• Chemical weathering occurs faster Chemical weathering occurs faster in hot, wet regions than it does in in hot, wet regions than it does in cold, dry regions.cold, dry regions.

• Mechanical weathering caused by Mechanical weathering caused by freezing and thawing occurs more freezing and thawing occurs more in cold regions than in hot regions.in cold regions than in hot regions.