1.b - influences of coastal system

Question 1

how does wind influence the coastline?

Answer 1

the wind is able to shape the coastline in 2 ways:
1. - the frictional drag that is has on the surface of the ocean is able to create waves which are capable of carrying out coastal marine erosion, transport and deposition.
the wind direction will have a strong influence on wave direction and wind strength should have an effect on wave height.
2. - the wind itself is able to carry out erosion, transportation and deposition.
these processes combine to create aeolian landforms, such as coastal dunes.

Question 1

what is the WAVE LENGTH?

Answer 1

the distance from crest to crest

Question 2

what is the wave crest?

Answer 2

the highest point of the wave

Question 3

what is the wave trough?

Answer 3

the lowest point of the wave

Question 4

what is swash?

Answer 4

the movement of water up a beach after a wave has broken

Question 5

what is backwash?

Answer 5

the flow of water down a beach after a wave has broken

Question 6

what is a SPILLING BREAKER WAVE?

Answer 6

they occur as waves travel across a gently sloping bottom (i.e. near the beach).
the wave breaks long and slow, losing its energy as white water spilling from the crest down the front of the wave.
water spills gently forward as the wave breaks

Question 7

what is a PLUNGING BREAKER WAVE?

Answer 7

occur as waves approach moderate to steep sea bottoms.
the wave becomes steeper than a spilling breaker
the crest falls as a well defined curve, falling forward with considerable energy
strong backwash, making them more destructive

Question 8

what is a SURGING BREAKER WAVE?

Answer 8

low angle waves breaking onto steep beaches
the wave slides forward and may not actually break

Question 9

how are waves created?

Answer 9

waves are created by the wind blowing over the surface of the water,
out to sea this creates OSCILLATION WAVES which will have no forward momentum of water, only energy is transferred forward,
the wave height depends on the strength and duration of the wind, the depth of the water and the length of the fetch

Question 10

what does wave height depend on?

Answer 10

the wave height depends on:
- the strength and duration of the wind
- the depth of the water and
- the length of the fetch

Question 11

what is a swell wave?

Answer 11

this is the name for the waves generated out at sea.
they have long wavelength and a wave period of up to 20 secs
this contrasts against locally produced storm waves, which have a greater wave height, shorter wavelength and wave period.

Question 12

what are the characteristics of a CONSTRUCTIVE WAVE?

Answer 12

low in height
long wavelength
low frequency (typically 6-8 per min)
break as spilling waves and strong swash travels a long way up the gently sloping beach
due to long wavelength, backwash returns to the sea before the next wave breaks, so the next swash movement is UNINTERRUPTED, and thus retains its energy
a key feature is that (therefore) swash energy exceeds backwash energy.

Question 13

what are the characteristics of a DESTRUCTIVE WAVE?

Answer 13

greater height
shorter wavelength
higher frequency (12-14 per min)
break as plunging waves so there is little forward transfer of energy to move water up the steeply sloping beach as swash.
friction from the steep beach slows the swash so it doesn’t travel far before returning down the beach as backwash
with a short wavelength, the swash of the next wave is often slowed by the frictional effects of meeting the returning backwash of the previous wave
swash energy is LESS that backwash energy.

Question 14

what is wind’s effect on the coastal landscape?

Answer 14

the source of energy for coastal erosion and sediment transport is wave action.
this wave energy is produced through the frictional drag of wind across the oceans surface.
THE HIGHER THE WINDSPEED AND THE LONGER THE FETCH, THE LARGER THE WAVES AND THE MORE ENERGY THEY POSSESS.

Question 15

how does the direction of wind influence the coastline?

Answer 15

onshore winds, blowing from the sea towards the land, are particularly effective at driving waves towards the coast.
if wind blows at an oblique angle to the coast, the resultant waves will also approach obliquely and generate long shore drift.

Question 16

what is wind?

Answer 16

wind is a moving force and as such is able to carry out erosion, transportation and deposition itself.
- these aeolian processes contribute to the shaping of many coastal landscapes.

Question 17

what is the significance of wind energy?

Answer 17

overall not very significant
wind could be considered significant as it is responsible for the strength, severity and direction of waves.
wind causes friction on the sea surface causing waves; the greater the fetch the bigger the waves.
the significance of wind CHANGES FROM DAY TO DAY MAKING IT A TEMPORALLY FACTOR.

Question 18

how do aeolian processes and the succession of plants work together to create dune complexes?

Answer 18

at low tide, incoming solar radiation (input of energy) is able to dry the sand out.
as the wind blows over the sand it is able to erode it by processes of deflation (erosion of clay and silt-sized particles by wind action in dry lands).
dry sand is much easier for wind to pick up than wet sand, as moisture increases cohesion between particles to help them stick together.
plant roots help to build up and stabilise sand (e.g. prickly saltwort.)
pioneer plant species are zerefite (well adapted)
e.g. they don’t lose water as easily by transpiration due to waxy leaves / deep roots to access nutrients.
plants act as a shield.

Question 19

what is a concordant coastline?

Answer 19

a coastline with bands of different geologies lying PARALLEL to the shore.

Question 20

what is a discordant coastline?

Answer 20

rock strata lies at right angles to the coast.
deep bays and pronounced headlands produced.
more resistant rocks form headlands, weaker rocks form bays.

Question 21

what is the angle of dip?

Answer 21

the angle of the strata (layers) in sedimentary rocks when compared to the horizontal.

Question 22

what types of current are there?

Answer 22

currents can either be local currents such as rip currents or tidal currents
or much larger ocean currents such as the North Atlantic Drift

Question 23

what are ocean currents?

Answer 23

large scale phenomena that are generated by convection from the Earth’s rotation

Question 24

how do rip currents form?

Answer 24

caused by tidal motion or by waves breaking at right angles to the shore.
a cellular circulation is generated by differing wave heights parallel to the shore.
water from the top of breaking waves with a large height travels further up the shore and then returns through the adjacent area where the lower height waves have broken.

Question 25

what impact do rip currents have on coastlines?

Answer 25

once rip currents have formed, they modify the shore profiles
by creating cusps
which help perpetuate the rip current, channelling flow through a narrow neck.

Question 25

how do warm and cold ocean currents alter UK coastlines?

Answer 25

warm ocean currents transfer heat energy from low latitudes towards the poles.
they change the temperature of water, (alters the amount of freeze-thaw weathering), which affects weathering processes and input of sediment to a system.
cold currents do the opposite (towards the equator) which therefore results in less effect on our coastlines.

Question 26

what causes tides?

Answer 26

The moon pulls the water towards itself, creating a HIGH TIDE, and there is a compensatory bulge on the other side of the earth.
At locations between the two bulges, there will be a LOW TIDE.
As the moon orbits the earth, the high tides follow it.
The highest tides will occur when the moon, sun and earth are all aligned and so the gravitational pull is at its strongest.
This happens twice each lunar month and results in SPRING TIDES with a high tidal range.
Also twice a month, the moon and the sun are at right angles to each other and the gravitational pill is therefore weakest, producing NEAP TIDES with a low range.
On a more local level, tides are controlled by the geomorphology of the sea bed and shape of the coastline.

Question 27

what are tides?

Answer 27

the periodic rise and fall of the sea’s surface
that are caused by the gravitational pull of the moon and (to a lesser extent) the sun

Question 28

what is tidal range?

Answer 28

the vertical difference in height between consecutive high and low waters over a tidal cycle.

Question 29

what influence do tides have on the coastline?

Answer 29

Tides determine the position at which the waves break on the beach, but also the range over which wave action can occur.
Tidal range can be a significant factor in the development of coastal landscapes.
In enclosed seas, such as the Mediterranean, tidal ranges are low and so wave action is restricted to a narrow area of land.
In places where the coast is funnelled, such as the Severn Estuary, tidal range can be as high as 14m.
The tidal range, therefore, influences where wave action and coastal processes can occur.
A small tidal range leads to erosional processes dominating.
A large tidal range leads to depositional processes dominating.
The zones where waves and long-shore currents move are shaped by the movements of tides.
Tidal range in combination with the topography of the area is critical because the higher the tidal range, the more impact is has on the coastline.

Question 30

what are spring tides?

Answer 30

The highest tides will occur when the moon, sun and earth are all aligned and so the gravitational pull is at its strongest.
This happens twice each lunar month and results in SPRING TIDES with a high tidal range.

Question 31

what are neap tides?

Answer 31

twice a month, the moon and the sun are at right angles to each other and the gravitational pill is therefore weakest, producing NEAP TIDES with a low range

Question 32

what are tides controlled by on a local level?

Answer 32

tides are controlled by the geomorphology of the sea bed and shape of the coastline.

Question 33

why does the tidal range vary across the planet?

Answer 33

shape of coastlines change
oceans are able to have a bigger difference

Question 34

how will having a large tidal range affect coastal processes/landforms?

Answer 34

arge tidal ranges results in more deposition
tidal range influences where wave action occurs, the weathering processes that happen on land exposed between tides and the potential scouring effect along coasts with a high tidal range.
deposition is dominant and creates a greater number of estuaries

Question 35

how will having a small tidal range affect coastal processes/landforms?

Answer 35

smaller tidal ranges result in more erosion due to the fact the waves are hammering a smaller area more often and with more force
wave energy is concentrated in a smaller area

Question 36

structure

Question 37

lithology