8.1 Coastal processes

Question 1

Fetch

Answer 1

The distance of sea over which the wind can blow. Coastlines which face a larger ocean have larger fetch.

Question 2

Wave crest

Answer 2

The top of the wave

Question 3

Wave trough

Answer 3

The low point between two wave crests

Question 4

Wave height

Answer 4

The difference in height between a wave crest and a wave trough

Question 5

Wave length

Answer 5

The distance between two wave crests

Question 6

Wave period

Answer 6

The time taken for a wave to travel through one wave length

Question 7

Wave velocity

Answer 7

The speed of movement of the wave crest

Question 8

Wave frequency

Answer 8

The number of waves that break on the beach in a given period of time

Question 9

Wave energy

Answer 9

Directly related to wave height. Wave energy is released when the wave breaks.

Question 10

Plunge line

Answer 10

The point at which the wave breaks

Question 11

Swash

Answer 11

The body of foaming water that rushes up the beach when a wave breaks. It obtains its energy from the energy released by the breaking wave.

Question 12

Backwash

Answer 12

The water which returns down the beach after a wave has broken.

Question 13

Storm waves

Answer 13

Large waves, produced by strong winds, blowing from the ocean directly onto the coastline.

Question 14

Plunging breakers

Answer 14

When storm waves break, they become vertical and plunge down onto the beach.

Question 15

Destructive waves

Answer 15

Waves that remove sediment from a beach. They are steep, high waves that have a short wavelength and a high wave frequency. They have a weak swash and strong backwash.

Question 16

Swell waves

Answer 16

If the wind that created the waves dies down over the ocean, the waves will continue to move in the same direction until they reach the coastline. When they reach the shore they will break gently.

Question 17

Surging breakers

Answer 17

A breaking wave that slides or surges up the beach.

Question 18

Constructive waves

Answer 18

Low, gentle waves that add sediment to a beach. They have a long wavelength and a low wave frequency. They have a strong swash and weak backwash.

Question 19

Berms

Answer 19

Ridges which form at the top of the beach, running parallel to the coastline. They are usually made of stones or shingle and are produced by the fortnightly spring tide.

Question 20

Orthogonals

Answer 20

Lines drawn at right angles to the wave crests as they approach the shore. They show how wave energy is concentrated or dispersed.

Question 21

Blowhole

Answer 21

A tube that grows upwards through the rocks from the roof of the cave. It is caused by wave quarrying and slowly erodes upwards along a weakness in the rock and eventually breaks through at the top of the cliff.

Question 22

Exfoliation

Answer 22

Weathering process which causes rock surfaces to peel.. Caused by expansion and contraction of surface layers of rock on the cliff face.

Question 23

Oxidation

Answer 23

Process of chemical weathering, particularly affecting iron minerals where there is addition of oxygen to a mineral.

Question 24

Halophytic

Answer 24

Salt-loving

Question 25

Storm beach

Answer 25

The top of the beach, formed by stones and pebbles thrown up by strong waves during a storm.

Question 26

Cuspate tombolo

Answer 26

When wave refraction causes LSD to operate in opposite directions either side of an offshore island, the beach extends out to the island, joining it to the mainland at low tide.

Question 27

Sediment cells

Answer 27

Inputs, outputs and movements of sediment within an area.