Coastal Processes And Land Formations

Question 1

What are the 4 types of erosional processes?

Answer 1

Abrasion
Attrition
Hydraulic action
Corrosion

Question 2

Abrasion

Answer 2

This is when sediment is moved along the shoreline, scraping across the floor causing it to get worn down over time

Question 3

Attrition

Answer 3

This is when rocks collide with eachother, wearing eachother down which leads to them being more round and smaller

Question 4

Hydraulic action

Answer 4

As a wave crashes onto a rock or cliff face, air is forced into cracks, joints or faults, within the rock. The high pressure causes the cracks to force apart and widen.

Question 5

Corrosion

Answer 5

The acidic sea water can cause rock such as limestone to erode away

Question 6

When are erosion rates the highest?

Answer 6

Erosion rates are the highest when:
- waves are high and have a ​long​ ​fetch​ (the distance the wind has travelled over the wave)
- waves approach the coast ​perpendicular​ to the cliff.
- at high tide​ - waves travel higher up the cliff so a bigger area of cliff face is able to be
eroded.
- heavy rainfall occurs​ - water percolates through permeable rock, weakening cliff.
- in ​winter​, destructive waves are the largest and most destructive

Question 7

What makes a rock vulnerable to erosion?

Answer 7

The resistance of a rock will determine its vulnerability to erosion and is influenced by various factors

Question 8

What rocks are resistant to erosion

Answer 8

sedimentary rocks like sandstone are clastic as they are made up of cemented sediment particles, therefore are vulnerable to erosion, whereas igneous and metamorphic rocks are made up of interlocking crystals, making them more resistant to erosion.

Question 9

What else affects the resistance of the rock?

Answer 9

The amount of cracks, fractures and fissures - the more weaknesses there are in the rock, the more open it is to erosional processes.

Question 10

What are the types of erosional landform

Answer 10

Caves, arches, stacks and stumps
Wave cut notches and platforms
Retreating cliffs

Question 11

How are caves, arches, stacks and stumps formed

Answer 11

Caves, Arches, Stacks & Stumps​ - This sequence occurs on pinnacle headlands. Marine erosion widens faults in the base of the headland, widening over time to create a cave. The cave will widen due to both marine erosion and sub-aerial processes, eroding through to the other side of the headland, creating an arch. The arch continue to widen until it is unable to support itself, falling under its own weight through mass
movement, leaving a stack as one side of the arch becomes detached from the mainland. With marine erosion attacking the base of the stack, eventually the stack will collapse into a stump.

Question 12

How are wave cut notches and platforms formed?

Answer 12

Wave-cut notch and platform​ - Marine erosion attacks the base of a cliff, creating a notch of eroded material between high tide height and low tide height. As the notch becomes deeper (and sub-aerial weathering weakens the cliff from the top) the cliff face becomes unstable and falls under its own weight through mass movement. This leaves behind a platform of the unaffected cliff base beneath the wave-cut notch.

Question 13

How are retreating cliffs formed?

Answer 13

Through the process of repeat wave-cut notches and platforms, new cliff faces are created, whilst the land retreats.