Weathering

Bell Ringer What are the three main types of rocks? Transformation through Heat and Pressure WITHOUT melting creates what type of rock? Pressure of sediment over type creates what type of rock? Cooled magma or lava create what type of rock?

Weathering

Weathering Definition: the process by which rocks break down and change Two Types: Mechanical Chemical

Mechanical Weathering Definition: Process where rocks break into smaller pieces with NO change in their composition Caused by: Cold temperatures Tectonic Processes Biological Activity

Mechanical Weathering 1. Frost Wedging- The repeated thawing and freezing of water in the cracks of rocks Water expands when frozen, chips away parts of the rock

Mechanical Weathering 2. Unloading- occurs when igneous rock becomes exposed through uplift and erosion Exfoliation-Occurs when pieces of the uplifted rock are weathered and chipped away

Mechanical Weathering 3. Biological Activity: Organisms can cause Mechanical Weathering Plant roots growing into cracks in rocks Burrowing animals moving rocks Decayed animals can produce acids (Chemical Weathering)

Chemical Weathering Definition: Rocks undergo changes in their composition Caused by: Water Oxygen Carbon Dioxide Acids

Chemical Weathering Hydrolysis-The reaction of water with other substances Oxidation-The reaction of oxygen with other substances

Chemical Weathering: Water 3. Water causes Chemical Weathering by absorbing gases from the atmosphere and ground CO2 +Water  Carbonic Acid Dissolves Rocks/Minerals Stalactites/Stalagmites

Differential Weathering Definition: When rocks weather at different rates Caused by different mineral compositions Sedimentary rocks weather more easily than igneous rocks

Statue of liberty The statue of liberty is made of copper which is generally a brownish color Has been affected by chemical weathering Water reacting with the copper Sulfuric acid formed by pollution (debatable)

Factors that Affect the Rate of Weathering