Wave , Fluvial and Aeolian Processes

Question 1

Wave processes

Answer 1

• Breaking waves erode the coastline through a range of processes.
• They also supply material to the system in the form of sediment which is either deposited or transported

Question 2

Abrasion / corrasion

Answer 2

Sand, shingle and boulders picked up by the sea and hurled against a cliff.

Question 3

Attrition

Answer 3

The wearing down of rocks and pebbled as they rub against each other , making them smaller and rounder.

Question 4

Hydraulic action

Answer 4

Occurs when waves break against a cliff and air and water become trapped in cracks and become COMPRESSED.

As the wave recedes, the pressure is released and the water and air suddenly EXPAND and the crack is widened.

Question 5

Wave pounding

Answer 5

Occurs when the mass of a breaking wave exerts pressure on the rock causing it to weaken.

High energy waves ~ exert a force of up to 30 tonnes per m^2.

Question 6

Solution / corrosion

Answer 6

Involves dissolving minerals.

When fresh water and salty water mix , acidity may increase and carbon- based rocks will be broken down.

Question 7

Solution ( transportation)

Answer 7

Dissolved material which is carried by the water.

This type of load is invisible .

The minerals remain in solution until the water is evaporated and they precipitate out of the solution.

Question 8

Suspension

Answer 8

very small particles carried in moving water.

Accounts for the muddy appearance of some sea water.

Larger particles can be suspended in storm events.

Question 9

Saltation

Answer 9

Small stones bounce along the sea bed.

This occurs when material can not be carried continuously through suspension, but picked up for a short distance only to be dropped again.

Question 10

Traction

Answer 10

Large boulders are rolled along the sea bed by the force of the flow.

may undergo a partial rotation before coming to rest again.

Question 11

Longshore drift

Answer 11

• Waves approach the coast at an OBLIQUE ANGLE due to the direction of the dominant wind.
• The SWASH carries material up the beach in the same direction as the wave.
• The BACKWASH moves the material PERPENDICULARLY back down the beach where it is picked up by the next incoming wave.

Question 12

Types of Erosion

Answer 12

• Abrasion / corrasion
• Attrition
• Hydraulic action
• Wave pounding
• solution

Question 13

Types of transportation

Answer 13

• Traction
• Saltation
• Suspension
• Solution
• Longshore drift

Question 14

Deposition

Answer 14

Occurs when velocity and / or volume of water decreases and energy is reduced.

Takes place in coastal environments when:
- sediment accumulation exceeds removal
- waves slow after breaking
- backwash percolates into beach material
- there is a sheltered area such as an estuary.

Question 15

Fluvial processes

Answer 15

The physical interaction of flowing water and the natural channels of rivers and streams.

Occurs in river mouths which have low energy.

Question 16

Fluvial erosion

Answer 16

• The main sources of a rivers sediment load is the upper catchment.
• Most channel erosion occurs during high-flow , high energy events.
• Sediment is also supplied by weathering and mass movement that result in material moving into river channels.

Question 17

Fluvial transportation

Answer 17

Rivers transport material in the same way as waves:
- traction
- suspension
- saltation
- solution

Question 18

Fluvial deposition

Answer 18

Material is deposited when:

• river enters the sea as there is a reduction in velocity as the flowing water enters the static body of sea water.
• tides and currents moving in the opposite direction create a major resistance.

Largest particles are deposited first and the finest particles are carried out further to sea.

FLOCCULATION of clay particles occurs when fresh water meets salt water, material clumps together due to electrical charges between them in saline conditions.

Question 19

Aeolian processes

Answer 19

Relating to or arising from the action of the WIND.

Coastal landscapes are exposed to open sea surfaces and heavily influenced by winds.

Question 20

Aeolian erosion

Answer 20

• Erosive forces increase exponentially with an increase in wind velocity.
• ATTRITION on land is more effective than in water as the material is carried for greater distances and the material is not protected from collisions by the film of water that surround material in rivers or sea.

Question 21

Aeolian transportation

Answer 21

DEFLATION ~ the removal of material as wind picks up sand particles and moves them.

• Dry sand is much easier for wind to pick up as wetter sand has more moisture which increases cohesion of sand particles making them stick together and become heavier.
• Exception of SOLUTION

Question 22

Aeolian deposition

Answer 22

• Wind speed slows down
• Usually due to surface friction
• occurs more inland as subject to surface irregularities for friction to occur compared to open water.
• Material carried by the wind is deposited.