Chapter 7 Section 1 Notes

Weathering – chemical and physical processes by which rocks break down Erosion – removal and transport of weathered material from one location to another

Mechanical Weathering / Chemical Weathering No change in composition -- Change in composition Temperature -Agents include: Repeated freeze / thaw water, O2, CO2, Acids Frost Wedging --Formation of new minerals and Pressure dissolution of others (calcite) Removing overburden -- Temperature increases rate Exfoliation – joints “cracks” --Water – hydrolysis - reactions Root Wedging -- Oxidation – rusting (formula) -- CO2 – Carbonic Acid (ground) -- Acid Rain – Sulfur dioxides --

Rates of Weathering – usually slow Climate – temp, precip, evaporation Chemical Weathering increases in more humid areas Physical Weathering rates increase in dry areas and areas with repeated freeze/ thaw cycles Rock Type and Composition Sedimentary rocks are easier to weather than Igneous and Metamorphic Rocks Mineralogy also affects the rate of weathering Surface Area Topography – slopes / elevation Vegetation – roots release weak acid