Weathering, Erosion, Transportation & Deposition Flashcards
what is physical weathering? (classification term)
the process by which a soil or rock increases its specific surface - the ratio of surface area to weight (in other words particle sizes are reduced)
what is mechanical unloading? (physical weathering)
when fissures occur in rocks due to shear stress resulting in horizontal cracks openings
what is mechanical loading? (physical weathering)
when rock is impacted by rain, sand, dust in the air or by sand, gravel and boulders carried by flowing water or by ice, results in material breaking away from the surface of the rock (usually in conjunction with another type of weathering that has already weakened the material)
what does wetting and drying do? (physical weathering)
has similar effects to freezing and thawing, clay minerals expand and contract dramatically
what is chemical weathering?
the process whereby primary rock and soil forming minerals are transformed to secondary rock and soil forming minerals (water has a big role)
what is solution in terms of weathering? (chemical weathering)
the simple dissolving of the rock in water - happens to salt and gypsum
what is carbonation in terms of weathering? (chemical weathering)
the process which relies on the slight acidity of water due to CO2 dissolving in the water which leads to the solution of chalk and limestone (think acid rain)
what is hydration in terms of weathering? (chemical weathering)
reversible reaction with water
what is oxidation in terms of weathering? (chemical weathering)
usually turns clays from blue-grey to brown - reaction of oxygen with a mineral to form an oxide, the breakdown of pyrites in shales is an example
what is hydrolysis in terms of weathering? (chemical weathering)
irreversible reaction with water and is responsible for the breakdown of most rock-forming minerals such as the decomposition of feldspar in granite to kaolinite
why is limestone problematic in terms of civil engineering (think weathering effects)?
the solubility of limestone in weakly acidic rainwater leads to many landscape features which can be very problematic for civil engineering - can dissolve and create large voids underground
do most chemical weathering processes happen faster in hotter or colder climates?
hotter climates generally
