8.1 Coastal processes

Question 1

Wave generation

Answer 1

Waves are created due to friction between wind and the sea surface.
Waves in deep water are different to those that break on shore

Question 2

Fetch

Answer 2

The distance over which the wind blows and the larger it is, the more powerful the waves will be

Question 3

Waves in oscillation

Answer 3

A forward movement of energy, the wave appears to be moving forward but water stays in a circular orbit.

Question 4

Waves of translation

Answer 4

Waves that reach the shore.
Base of the wave has contact with the seabed causing friction, slowing down the wave.
Bunches the wave up, reducing wavelength while increasing wave height.

Question 5

Spilling breakers

Answer 5

Gentle beach gradients and steep waves, gradual peaking of a wave until crest becomes unstable and gently spill forward.

Question 6

Plunging breakers

Answer 6

On steeper beaches, waves of intermediate steepness.
The shoreward face of the wave becomes vertical, curling over and plunging forward and downwards.
(Pro surfing waves)

Question 7

Surging breakers

Answer 7

Steep beaches with low steepness waves.
The front face and crest of the wave remain smooth and the wave slides directly up the beach without breaking.
A large proportion of wave energy is reflected back at the beach.

Question 8

Constructive waves

Answer 8

Low wave frequency, waves on a gently sloping sea floor.
A gentle offshore slope creates a gradual increase in friction, causing a gradual steepening of the wavefront.
Strong swash and weak backwash causing beach to be built up.

Question 9

Destructive waves

Answer 9

Locally generated winds create waves of high frequency per minute.
Creates a rapid increase in friction causing a very steep plunging breaker where water movement is circular.
Wave is accelerated by the sea bed’s steep gradient, making the wave destructive.

Question 10

Wave Refraction

Answer 10

Waves turn and lose energy around a headland on uneven coastlines. the wave energy is focused on the headlands, creating erosive features. the energy is dissipated in bays creating low energy environments such as beaches.

Question 11

Hydraulic action

Answer 11

As waves crash onto a rock or cliff faces, any air trapped in cracks or joints is put under great pressure.
As wave retreats, the pressure is released with explosive force (cavitation).

Question 12

Corrasion

Answer 12

Breaking waves pick up material such as pebbles and shingle which are hurled against a cliff face wearing it down.

Question 13

Attrition

Answer 13

Rocks that the sea is carrying knock against each other, they break apart to become smaller and more rounded.

Question 14

Solution

Answer 14

Mildly acidic seawater causes alkaline rocks (Limestone) to be eroded.
Limestone and chalk are susceptible to this however not all rocks are affected.