how are coastal landforms developed - weathering

Question 1

what is weathering

Answer 1

weathering uses energy to produce physically or chemically altered materials from the surface rock

Question 2

3 types of weathering

Answer 2

physical/ mechanical
chemical
biological

Question 3

what is physical/ mechanical weathering and the 4 types

Answer 3

• the breakdown of rock to produce smaller fragments of the same rock
• no chemical changes take place
  freeze thaw
  pressure release
  thermal expansion
  salt crystallisation

Question 5

freeze-thaw weathering

Answer 5

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 6

pressure release

Answer 6

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 7

thermal expansion

Answer 7

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

Question 8

salt crystallisation

Answer 8

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 9

what is chemical weathering

Answer 9

• the decay of rock involving chemical reactions
• alters the rocks chemical composition
• chemical reactions increases thermal energy stores

Question 10

what are the 5 types of chemical weathering

Answer 10

oxidation
carbonation
solution
hydrolysis
hydration

Question 11

oxidation

Answer 11

minerals in rocks react with oxygen in air or water

Question 12

carbonation

Answer 12

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 13

solution

Answer 13

• 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 14

hydrolysis

Answer 14

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

Question 15

hydration

Answer 15

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

Question 16

what are the 2 types of biological weathering

Answer 16

tree roots
organic acids

Question 17

tree roots

Answer 17

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

Question 18

organic acids

Answer 18

• 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