Weathering + Erosion Flashcards
(14 cards)
Physical weathering is…
…The breakdown of rock in situ due to physical processes.
Examples are:
Freeze thaw
Insolation/Onion skin
Chemical weathering is…
…The breakdown of rock in situ due to chemical processes.
Examples are:
Acid rain/Carbonation
Oxidisation
Hydraulisis (Kaolinisation)
Biological weathering is…
…The breakdown of rock in situ due to biological processes.
Examples are:
Tree roots
Animal burrows
Human/other animal activity
Freeze thaw weathering happens when…
…Temperate fluctuates above and below 0°, rainfall enters cracks or joints in rock, expands fracture weakening rock and displacing it.
Insolation needs…
…Large temperature fluctuations. Rock contracts when cool at night, yet expands when it’s hot in the day forming joints due to repeated movement (expansion + contraction) joints fall off in layers like an onion.
Carbonation affects…
…Chalk and Limestone because they are made of calcium carbonate (Calcite). CO² from the atmosphere dissolves in rain forming weak carbonic acid (Acid rain) which dissolves calcite. Creates CO² and ions in solution.
This is what makes the sea salty
Oxidisation requires…
…Oxygen from the air, water and an iron rich rock such as Basalt. The Iron in the rock oxidises (rusts) and is replaced with both hematite and ions in solution.
Hydrolysis is also known as…
…Kaolinisation, and it needs water to react with Orthoclase feldspar in granite (this happens in Kernow, predominantly near St Austell). The muscovite and quartz in the granite are resistant and as the water reacts with the Orthoclase (which is sped up by radioactive decay in the earth heating up the granite increasing the reaction speed) it makes Kaolinite (China clay) as the product.
Feces weathering is both…
…Chemical and Biological
Erosion is defined as…
…The breakdown of rock during or due to transportation (Movement).
What are examples/methods of transportation in geology?
Rivers
Wind
Seas
Gravity
Ice
What are examples of transportation in Rivers?
Traction (Rolling + Sliding) [Always in contact with riverbed]
Saltation (Bouncing) [Sometimes in contact with riverbed]
Suspension (Floating away n shit) [Grains never in contact with the Bed]
Solution [Dissolved ions]
How are grains broken down?
Attrition (Bumping into other grains)
Abrasion (Rubbing against other grains or surfaces)
Corrosion (Dissolves Limestone)
Transportation key points:
Transportation is the movement of sediment (Products of weathering + Erosion).
Movement is dependent on size + current velocity.
Decreased current = Deposition.
