Weathering Process and Agents Quiz

Study Notes

Weathering is the process where rocks break down into smaller pieces, are worn away, or are dissolved.
It's caused by both abiotic (non-living) and biotic (living) factors.
Biotic factors are caused by living things like animals and humans.
Abiotic factors are non-living, physical, and chemical components of the environment.
Weathering does not involve the movement of materials during decomposition.

Chemical Weathering:
- Changes due to chemical activity.
- Modifies rock composition.
- Agents of chemical weathering: oxygen, rainwater, carbon dioxide, and acids.
- Products of chemical weathering include clay minerals, metal ores, oxide minerals, and rounding boulders.
Mechanical or Physical Weathering:
- Due to physical stresses.
- Changes physical attributes, but composition stays the same.
- Occurs due to changes in temperature and pressure.
- Major processes: frost wedging, exfoliation, and thermal expansion and contraction.
Organic or Biological Weathering:
- Plants, animals, and microorganisms are agents of rock disintegration.
- Integration of mechanical and chemical weathering.
- Plants growing on rocks.
- Lichen and algae inhabiting rock surfaces, releasing organic acids that consume minerals, increasing susceptibility to mechanical/chemical weathering.

Dissolution: Elements dissolve in water.
Hydrolysis: Positive ions are replaced by active hydrogen ions that come with water.
Oxidation: Oxygen interacts with minerals.

Frost wedging: Water expands when it freezes, putting pressure on rocks, causing them to crack. Water is the key agent, affected by temperature changes.
Exfoliation: Detachment of sheets of rocks due to instability in pressure. Pressure inside the rock is greater than the pressure on the surface of the rock permitting expansion.
Thermal expansion and contraction: Alternating expanding and contracting of crystals due to heating and cooling. Extreme and sudden changes in temperature (like campfires) can trigger this.