Climatic Factors Affecting Weathering and Peltier’s Diagram
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Climate is the main force driving weathering as it determines the type of weathering that will take place. In addition, climate also determines the availability and development of other factors such as vegetation.
Cold regions such as Scandinavia promote freeze thaw weathering as temperatures are low and water is not supplied very often. The little water that collects in between cracks can be recycled by episodes of freezing and thawing generating stresses within the rock.
Insolation weathering is most dominate in arid, semi arid and subtropical regions as there is repeated heating during the day and cooling at night causing the rock to expand and contract respectively generating stresses. Salt crystallisation is often common in arid regions due to high rates of evaporation and or along coasts were salt water form seas is abundant.
In tropical regions, chemical weathering such as chelation and oxidation are more dominate since water, heat and vegetation is in abundant supply.
Since chemical weathering often result in residual clays and near complete breakdown of the entire rock, slopes in the tropics are often gentler than in in arid or subtropical climates.
Louis Peltier related rainfall and temperatures to different types of weathering. He argued that physical weathering was more dominate (strong) in regions with very low rainfalls and temperatures and tend to weaken as temperatures slightly go high.
He also argued that chemical weathering is strong in regions with high temperatures and rainfall. Peltier also noted that no weathering took place at low rainfalls and high temperatures.
Peltier’s diagram, however has limits to it. His diagram tend to ignore other types of physical weathering such as insolation which occur at high temperatures.
His studies seemed to be based on freeze thaw as the main physical weathering neglecting other types of physical weathering that occur at high temperatures such as salt weathering and insolation.
However, his studies on chemical weathering provides us with a good overview on high temperatures and rainfall which are needed for chemical reactions.