Weathering: Earth’s surface rocks are influenced by the weathering processes. Literally, they are
exposed to the weather. The immediate surface is usually soil (1-2m thick), which is the most highly weathered material. Next, the weathered bedrock just below is referred to as regolith (literally a mixed pile of dirt, gravel, rocks, etc). Below that is solid bedrock. Fractures (or joints) in the bedrock are what allow for the exposure of the rock to the external elements
Profile of a Weathered Surface (started as solid bedrock)
A. Physical Weathering Processes: Physical weathering is the mechanical breakdown
(e.g. crushing, breaking) of solid rock into smaller pieces. It is important to note that physical and chemical weathering often operate simultaneously; we separate them for convenience.
1. Frost Action (also called Frost Wedging)
2. Salt-Crystal Growth (also called Crystallization)
3. Hydration – some consider this chemical weathering,
4. Pressure Release Jointing
5. Root Wedging
6. Thermal Expansion– Rock expands as it heats and contracts as it cools;
this causes cracking.