weathering and sedimentary rocks

• Weathering is the breakdown of in-situ rock materials near the earths surface by exposure to the atmosphere, water and organic matter.
• Erosion is the removal of weathered products by gravity, water, wind and ice.
• Products of weathering include rock fragments, un-reactive quartz grains, clay minerals, and ions in solution.
• Mechanical/physical weathering leads to disintegration of bedrock to smaller angular but chemically identical fragments.
• Mechanical processes contributing to weathering include freeze-thaw, exfoliation, and pressure release.
• Chemical processes contributing to weathering include carbonation, hydrolysis, and oxidation.
• Spheroidal weathering occurs when rectangular blocks outlined by joints undergo chemical weathering, with the corners and edges weathering more rapidly.
• Biological activity, such as tree roots widening joints and bedding planes, can contribute to weathering.