1. Chapter 7 Section 1 Notes

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

3. 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 --

4. 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