Chapter 7 Notes Weathering

Section 7.1 Notes—Weathering  Weathering is the process by which rocks on or near Earth’s surface break down and change.  Erosion is the removal and transport of weathered material from one location to another.  There are two types of weathering: mechanical and chemical.  Mechanical weathering is the process by which rocks break down into smaller pieces. It is also called physical weathering and doesn’t involve any change in the rock’s composition.  Water is the most important agent of mechanical weathering, but wind also plays a role.  Two factors that influence the amount of mechanical weathering that will occur are: temperature and pressure.  Chemical weathering is the process by which rocks and minerals undergo changes in their composition as a result of chemical reactions.  There are four agents of chemical weathering: water, oxygen, carbon dioxide, and acid precipitation.  Four factors that affect the rate of weathering are: climate, rock type, surface area, and topography.  Climate plays a role in weathering because certain climates encourage different types of weathering. Chemical weathering occurs most readily in warm, humid climates. Physical weathering occurs most readily in cool, dry climates.  Sedimentary rock types are more easily weathered than any other type of rock.  As the surface area of a rock increases due to weathering, the rate of weathering also increases.  Rocks that are located on a slope are more likely to be weathered because gravity can cause them to move more readily.