Weathering Weathering Weathering Breaking down of rocks into - PowerPoint PPT Presentation

Weathering

Weathering Weathering – Breaking down of rocks into simpler components • Size • Composition Mechanical Weathering – Changes size and shape of the rock but not its chemical composition • Temperature Change • Abrasion • Unloading • Biological Activity

Weathering Chemical Weathering – Changes the rock into one or more new compounds (changes its chemical composition) Water - most important agent of chemical weathering Dissolved gases in water react with chemicals in rock • O 2 • CO 2 • NO 2 Acid Rain • SO 2

Importance of Weathering Mechanical Weathering • Easier to move • More prone to chemical weathering Chemical Weathering • Make new raw materials Mechanical & Chemical Weathering Together • Changes landforms • Makes soil (sand, silt, and clay) • Increases rate of weathering

Factors Affecting the Rate of Weathering When analyzing weathering, look at: • Rock Material • Composition • Surface Area • Climate • Temperature • Precipitation

Factors Affecting the Rate of Weathering Rock Composition • Mineral composition and solubility • Minerals that make up the rocks • Physical features such as shape, joints, and cracks Surface Area • Strongly tied to rock composition • Increase surface area = increased exposure to environment

Factors Affecting the Rate of Weathering Temperature • Increased temperature = increased chemical weathering (chemical reactions more active in higher temperatures) • Temperate (mix of cold and warm) temperatures are required for effective mechanical weathering Precipitation • Increased precipitation = increased weathering • Need contact of rock with water for chemical weathering • Water is required for most mechanical weathering

Chemical Physical Weathering

http://transcripts.cnn.com/2000/US/08/08/wildfires.03/colorado.mesa.ve

http://www.gorzow.mm.pl/~bebelebe/Anasazi%20Ruins,%20Mesa%20Verde%20National%20Park,%20Colorado.jpg

http://www.dustydavis.com/blogimages/mesa_verde_close_large.jpg

http://www.russfinley.com/stockphotography/mesaverde/mesaverde01.j

Effects of Weathering