costal environments

Question 1

what is the definition of a coast?

Answer 1

the coast is a narrow contact zone between the land and sea.

Question 2

coastal environments consist of 2 parts: onshore and offshore. how many kilometres does the onshore go inland and the offshore go out to the sea?

Answer 2

onshore - up to 60 km inland

offshore - up to 370 km out to the sea

Question 3

which 3 factors determine the size of waves?

Answer 3

1. wind duration
2. wind speed
3. fetch ( the distance over which the wind blows over the sea)

Question 4

what are the 2 types of waves?

Answer 4

1. destructive

2. constructive

Question 5

what are features of destructive waves?

Answer 5

1. have a lot of energy and force
2. tall waves
3. high frequency
4. have a greater backwash than swash

Question 6

what are features of constructive waves?

Answer 6

1. small, weak
2. low frequency
3. have a greater swash than backwash

Question 7

what are the 4 main factors that affect the coast?

Answer 7

1. land
2. human activity
3. weather and climate
4. sea

Question 8

why do waves break?

Answer 8

waves break when the trough (bottom part of the wave) slows down by friction with the sea bed which becomes shallower as it approaches the coast.

Question 9

what are the 5 types of erosion?

Answer 9

1. corrAsion
2. corrOsion
3. hydraulic action
4. hydraulic pressure
5. attrition

Question 10

what are the 3 types of weathering?

Answer 10

1. freeze-thaw weathering
2. crystallisation
3. biological weathering

Question 11

describe: mass movement: Rockfall

Answer 11

fragments of rocks weathered from the face of the cliff fall and collect at the foot of the cliff (gravity)

Question 12

describe: mass movement: Rotational slumping

Answer 12

this mostly occurs when the foot of the cliff is eroded by wave action. this makes the cliff steeper, the cliff can then slide (rotate) downwards. is the cliff is made out of porous rock (eg. chalk) then it absorbs water which makes it heavier. this extra weight and the water which also acts as a lubricant causes a rotational slump.

( a layer of clay may become slippery, speeding up the process)

Question 13

what is refraction ( in waves)?

Answer 13

this is the bending of the waves when approaching the coastline.

( waves in shallower water slow down, where as waves in deeper water go faster. this happens near headlands. waves appear to bend, where as some waves only become slower and the others carry at their previous speed.)

Question 14

what is diffraction? (not refraction)

Answer 14

waves that move through a fairly narrow gap slow down on the sides. where as the the wave continues at its normal velocity in the mid point (middle) this makes a curved shape.

Question 15

what is Long shore drift (LSD)

Answer 15

long shore drift is when waves approach the beach at an angle. the waves effectively carry sand and shingle up the beach at an angle in a particular direction, this material is then later pulled vertically down the beach by backwash and gravity. If the direction is constant the material will gradually shift along the beach in a zig-zag way.

(groynes- these prevent the movement of the sand along the shore. this leads to the sand becoming ´´trapped`` which forms beaches.