Factors affecting the weathering Flashcards
Factors affecting weathering:
- climate
- rock type and structure
- vegetation
- relief
For climate is it very difficult to…
isolate the exact relationship at any scale between climate type and rate of processes.
Peltier’s diagram shows the relationship between…
moisture availability and the average annual temperature.
Chemical weathering increases with…
moisture and heat.
Van’t Hoff’s Law states that…
the rate of chemical weathering increases 2-3 times for every increase in temperature of 10 degrees. (up to 60)
Climate factors:
- moisture availability
- frequency and extent of freezing
- diurnal temperature change
- average temperature
Moisture availability is essential for…
most physical weathering processes. Hydration, hydrolysis, carbonation, solution.
Frequent frosts and thaws cause…
frequent expansions and contractions, very effective at fragmenting rocks.
Diurnal temperature range influences…
exfoliation and alternate expansion and contraction of minerals.
Average temperature regulates…
in combination with water, biotic activity. So, root action, carbonation due to increased CO2 production.
Rock type influences the rate and type due to:
- chemical composition
- the nature of cements in sedimentary rock
- joints and bedding planes
Iron-oxide based…
cements are prone to oxidation, whereas quartz cements are very resistant.
The cement forms…
an integral and important part of the rock and its structure affects the porosity and permeability of the rock.
Greater porosity allows…
easir entry of water, air, roots and soil organisms.
Fractures in rock represent…
weak points which physical, chemical and biological processes can exploit.
Relief is important as…
on slopes, weathered material moves downhill, exposing fresh rock to further weathering.
Weak minerals:
Olivine, Augite
Strong minerals:
Quartz, feldspar(in granite, makes it stronger)
Soil cultivation may…
change the composition of soil air, which influences chemical weathering and the entry of water and organisms.
Acidification is caused by…
release of CO2 and oxides of sulphur and nitrogen. This causes acid rains.
The influence of vegetation is linked with…
the type of climate and the nature of the soil.
The depth of the soil may have an effect on…
the amount of weathering that occurs. Soil may protect rocks from a further breakdown or increase the rate breakdown due to the vegetation support.
There may an important temperature difference between…
south and north facing slopes. E.g. due to wind, rain shadow.
