key term etst

Question 1

freeze-thaw weathering

Answer 1

water enters cracks and joints and expands by 10% when it freezes. this exerts pressure on the rock causing it to split or parts break off

Question 2

pressure release

Answer 2

a type of physical weathering caused when rocks that are under a great amount of pressure no longer have to bear a heavy load, causing expansion and fracturing.

Question 3

thermal expansion

Answer 3

rocks expand when heated and contract when cooled. when this happens lots layers may crack and flake off - insolation weathering

Question 4

salt crystalisation

Answer 4

solutions of salt seep into pore spaces in porous rocks. then the salt precipitates - forming crystals. the growth of these crystals causes the rock to disintegrate

Question 5

oxidation

Answer 5

minerals in rocks react with oxygen in air or water

Question 6

carbonation

Answer 6

occurs when carbon dioxide from moisture in the air reacts with carbonate minerals found in rock. This creates carbonic acid which breaks down rock.

Question 7

solution

Answer 7

• any process where a mineral dissolves in water
• some salts are soluble in water
• other minerals eg iron are only soluble in very acidic solutions

Question 8

hydrolysis

Answer 8

the breakdown of rock by acidic water to produce clay and soluble salts.

Question 9

tree roots

Answer 9

tree roots growing into cracks or joints in rocks and exert outward pressure.

Question 10

organic acids

Answer 10

• organic acids are produced during decomposition of plant and animal litter
• this causes soil water to become more acidic and react with minerlas in a process called chelation

Question 11

hydration

Answer 11

occurs when water is absorbed by minerals in the rock, creating crystals which exert pressure on the surrounding rock, eventually causing it to crumbl