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Flashcards in Types of weathering Deck (12)
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1
Q

types of mechanical weathering are (3)

A
  • freeze thaw weathering
  • salt crystallisation
  • wetting and drying
2
Q

freeze thaw weathering is when

A
  • water enters cracks in the rock face and freeze, expanding in doing so and so putting stress on the rock fissure
  • the water then melts, and the rock relaxes
  • this repeated over time means pieces of rock fall off, and the rock below expands with the release of pressure, so forms new cracks
  • this makes the new layer of rock susceptible to further weathering
3
Q

salt crystallisation is when

A

salt from sea water forms crystals inside cracks when the water evaporates, building up pressure and expanding the cracks

4
Q

wetting and drying is when

A

some permeable rocks such as clay expand when they absorb water and retract when dry, so form cracks which make it vulnerable to freeze thaw weathering and salt crystallisation

5
Q

biological weatheirng is when

A

rock is broken down by plant or animal activity

6
Q

three examples of biological weathering are:

  • (shellfish)
  • (algae and fungi)
  • (roots)
A
  • the piddock shellfish has a shell which drills into soft chalk rock and so weakens its structure
  • algae and fungi can break down minerals and create solution, so ‘dissolving’ the rock surface
  • plant roots exploit cracks int he rock and grow, so expanding the crack and weakening the structure
7
Q

types of chemical weathering are (4)

A
  • oxidation
  • hydration
  • hydrolysis
  • carbonation
8
Q
  • oxidation is when

- and the rocks most affcted are

A
  • when rocks disintegrate as oxygen dissolved in sea water reacts with minerals to produce hydroxides and oxides
  • ferrous rocks are especially affected (iron rich)
9
Q

hydration is when

A

when water is added to rock and the rock expands, forming cracks and then weakening the structure. permeable rocks such as limestone are most affected

10
Q

hydrolysis is when

A

when midly acidic water reacts with rock, it creates dissolved clays and salts, which degrades parent rock and weakens it

11
Q

carbonation is when

A
  • when dissolved CO2 in rainwater forms weak carbonic acid (H2CO3).
  • this reacts with rocks such as chalk or limestone to form bicarbonates which then dissolve easily in water, so are washed away.
12
Q

what product of fossil fuel combustion adds to carbonation

A

sulphur dioxide and nitrogen dioxide