Coastal Processes

Question 1

Define corrasion/ abrasion?

Answer 1

Bits of rock and sediment transported by the waves smash and grind against rocks and cliffs, breaking bits off and smoothing surfaces.

Question 2

Define hydraulic action?

Answer 2

Air in cracks in cliffs is compressed when waves crash in. The pressure exerted by the compressed air breaks off rock pieces.

Question 3

Define cavitation?

Answer 3

As waves recede, the compressed air expands violently, again exerting pressure on the rock and causing pieces to break off.

Question 4

Define wave quarrying?

Answer 4

The energy of a wave as it breaks against a cliff is enough to detach bits of rock.

Question 5

Define solution?

Answer 5

Soluble rocks get gradually dissolved by the seawater.

Question 6

Define attrition?

Answer 6

Bits of rock in the water smash against each other and break into smaller bits.

Question 7

What are the 4 main processes of transportation?

Answer 7

Solution, suspension, saltation and traction.

Question 8

Define solution?

Answer 8

Substances that can dissolve are carried along in the water.

Question 9

Define suspension?

Answer 9

Very fine material, such as silt and clay particles, is whipped up by the turbulence and carried along the water. Most eroded material is transported this way.

Question 10

Define saltation?

Answer 10

Larger particles such as pebbles or gravel are too heavy to be carried in suspension. Instead, the force of the water causes them to bounce along the sea bed.

Question 11

Define traction?

Answer 11

Very large particles are pushed along the sea bed by the force of the water.

Question 12

Describe the process of longshore drift?

Answer 12

Swash carries sediment up the beach, parallel to the prevailing wind. Backwash carries sediment back down the beach, at right angles to the shoreline. When there’s an angle between the prevailing wind and the shoreline, a few rounds of swash and backwash move the sediment along the shoreline.

Question 13

Define deposition?

Answer 13

When material being transported is dropped on the coast.

Question 14

Define sub aerial weathering?

Answer 14

The gradual break down of rock by agents such as ice, salt, plant roots and acids.

Question 15

Describe the process of salt weathering?

Answer 15

Salt weathering is caused by saline water. This saline water enters pores or cracks in rocks at high tide. As the tide goes out the rocks dry and the water evaporates, forming salt crystals. As the salt crystals form they expand, exerting pressure on the rock - this causes pieces to fall off.

Question 16

Describe the process of freeze thaw weathering?

Answer 16

Freeze thaw weathering occurs in areas where temperatures fluctuate above and below freezing. Water enters the joints in the rock and if the temperature drops below freezing the water freezes and expands. Over time repeated freeze thaw action weakens the rocks and causes pieces to fall off.

Question 17

Describe the process of chemical weathering?

Answer 17

Chemical weathering is the breakdown of rock by changing its chemical composition. For example, carbon dioxide in the atmosphere dissolves in rainwater forming a weak carbonic acid. This acid reacts with rock that contains calcium carbonate, so rocks are gradually dissolved.

Question 18

Describe biological weathering?

Answer 18

Biological weathering is the growth of plant roots into cracks in the rocks and widening them which can cause the rocks to break down.

Question 19

Describe the process of mass movement?

Answer 19

The shifting of material downhill due to gravity. In coastal areas, it is most likely to occur when cliffs are undercut by wave action- this causes an unsupported overhang, which is likely to collapse.

Question 20

Name 4 types of mass movement?

Answer 20

Landslides, slumping, rockfalls and mudflows.

Question 21

Why are unconsolidated rocks prone to collapse?

Answer 21

As there’s little friction between particles to hold them together.

Question 22

Why can heavy rain increase the likelihood of a collapse?

Answer 22

It can saturate the unconsolidated rock further reducing its friction and making it more likely to collapse.

Question 23

Describe the process of runoff?

Answer 23

The flow of water over land can erode fine particles and transport them downslope.