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Agents of Weathering

Answer Text:
Agents of Weathering
a) Heat
-Is one of the most important agents of weathering. May act either directly through fluctuation in temperature which exerts stress upon rocks, or indirectly through its influence on chemical reactions within the rock
b) Water
- Most water entering the active weathering zone of the earth is derived from rainfall.
- Both the chemical and the physical characteristics of this water are important.
- Pure water is composed of hydrogen and oxygen
of two hydrogen ions to one oxygen ion (H2O).
- Combination of these elements is not always stable, and the water molecules tend to separate (dissociate) to provide individual hydrogen (H+) and hydroxyl (OH) ions.
- The water that contains excess of free hydrogen
ions is acidic and generally able to weather rock minerals more rapidly and readily.
c) Dissolved Substances
- Many other substances may also become dissolved in rain water, increasing its weathering ability.
- For example, pollutants such as Sulphur dioxide may convert the water to weak sulphuric acid, while organic compounds washed from the vegetation produce weak organic acids.
d) Plants and Animals
- The activities of burrowing animals such
as rats and rodents enhance weathering.
- Plants roots penetrate through rocks joints causing stress and cracks thus facilitating the weathering process.
- Human activities such as burning of the vegetation cause stress due to intense heating
of the rocks resulting to weathering