Weathering What is weathering The process that breaks

Weathering

What is weathering? The process that breaks down rock into smaller pieces, called sediments. Not to be confused with WEATHER!

There are two types of weathering: Mechanical Weathering Chemical Weathering (physical) Rocks are physically broken into smaller pieces. Rocks are broken down through chemical changes. The rate of weathering is affected by climate. Mechanical happens faster in the cold weather. Chemical is faster in warm weather.

Forms of Mechanical Weathering Ice Wedging Exfoliation Abrasion Plants and animals

Ice Wedging (a. k. a. Frost wedging) The cycle of water freezing and thawing in the cracks of rocks, causing the rock to break. Click the picture for ice wedging animation!

Exfoliation Pressure causes rocks to crack and “peel’ away in slabs.

Abrasion Sediments carried by wind or water rub against other rock and wear it down. Like sandpaper!

Plant Wedging Plant roots grow large and break apart rock.

Animals burrow into the ground and loosen sediment and soil.

Surface Area of Rock As rock is broken apart by mechanical weathering, the amount of rock surface area exposed to air and water increases. These smaller pieces will be weathered faster than a larger piece.

1. What is weathering? EXIT SLIP 2. How do mechanical weathering and chemical weathering differ? 3. What type of weather conditions would increase the rate of chemical weathering? 4. The diagram shows the process of ice wedging. Explain how this process physically weathers rocks. 5. How can plants and animals contribute to the mechanical weathering process?

Forms of Chemical Weathering Oxidation Dissolution Hydrolysis Organic Acids

Oxidation When materials that contain iron are exposed to oxygen and water, they become a reddish color. Ayer’s Rock, Australia

Dissolution Carbonic acid in rain dissolves rock. This can form caves and cause sinkholes.

Hydrolysis Water combines with the minerals in rock and cause a chemical change. If water combines with the mineral feldspar, clay is formed.

Organic Acids Plant roots give off acids that dissolve rock.

EXIT SLIP 6. Oxidation occurs when materials that contain iron are exposed to what two compounds? 7. Dissolution can form sinkholes. Explain the process of dissolution. 8. How do plants and animals chemically weather rocks?

Can you tell which mountain is older?

What is soil? A mixture of weathered rock, decayed organic matters, mineral fragments, water, and air.

Factors Affecting Soil Formation