The Rock Cycle

Weathering and Erosion

• Weathering is the process responsible for the physical/mechanical breakdown and chemical alteration of rocks at or near Earth's surface.

Erosion

• Mobile agents responsible for the physical removal of material in erosion are water, wind, ice, and gravity.

Gravity-Driven Processes

• Mass wasting involves the transfer of rock and soil downslope under the influence of gravity.

Agents of Weathering

• The main agents that attack fresh rock of the geosphere are temperature, water, oxygen, and living organisms.

Result of Weathering

• The result of weathering is the formation of regolith, a loose, unconsolidated rock debris.

Types of Weathering

• Freeze-thaw weathering occurs when water freezes and expands in fractures of rocks, causing mechanical breakdown.
• Chemical weathering is the principal agent of alteration, where minerals in rocks react with the environment to form new compounds.
• Thermal weathering involves the expansion and contraction of rocks due to heating and cooling, causing mechanical breakdown.

Weathering Processes

• Mechanical weathering (physical breakdown) and chemical weathering work together to break down rocks into regolith.

Chemical Weathering

• The result of chemical weathering on minerals in igneous and metamorphic rocks is the formation of new minerals, such as clay, and the release of nutrients.