Year 11 Coasts

Question 1

Where are waves generally larger

Answer 1

Larger in s.w than s.e because waves formed by wind blowing over the sea

Question 2

How do waves break

Answer 2

The bottom of the waves touch the sand, slows down and topples over (the top of the wave)

Question 3

Qualities of destructive waves

Answer 3

Short wavelength, high frequency 10-14 wpm
steep wave front
gains much height over 1m

Question 4

How do destructive waves act and when and where are they found

Answer 4

Restricted swash, strong backwash
Plunges onto beach, doesn’t travel far up beach
Found in exposed bays, build up pebbled bays
more common in winter, high energy

Question 5

Qualities of constructive waves

Answer 5

Long wavelength, low frequency 8-10 wpm
Gentle sloping wavefront
low wave height under 1m

Question 6

How do constructive waves act and when and where are they found

Answer 6

Strong swash, weal backwash
Found in sheltered bays and spits where they build up sandy beaches. more common in summer
low energy

Question 7

Process of coastal erosion

1.

Answer 7

Hydraulic action

air trapped in rocks or cliff face. when wave breaks, trapped air is compressed and weakens the cliff

Question 8

Process of coastal erosion

2.

Answer 8

Abrasion

Bits of sand and pebbles carried in waves wear away at cliff face like sandpaper

Question 9

Process of coastal erosion

3.

Answer 9

Attrition

Waves smash grinding down load particles. during transport, pebbles collide over time break into smaller pebbles

Question 10

Process of coastal erosion

4.

Answer 10

Solution

Sea contains acids which dissolve rock causing it to wear away. sea water reacting with rock through chemical reaction

Question 11

When does deposition occur

Answer 11

Low energy, sheltered bays
If a large source of sediment updrift
large expanses of beach
Engineered structures (groynes) trap sediment

Question 12

What is mass movement

Answer 12

Shifting of rocks and loose material down a slope. happens when force of gravity greater than supporting force

Question 13

What is rockfall

Answer 13

Fragments of rock break away from cliff face often due to freeze-thaw

Question 14

What is a landslide

Answer 14

Blocks of rock slide downhill

Question 15

What is a mudflow

Answer 15

Saturated mud, soil and weak rock flow downhill

Question 16

What is rotational slip

Answer 16

Slump of saturated soil and weak rock along curved surface

Question 17

What’s fetch

Answer 17

Distance wave travels across open water

Question 18

What is backwash

Answer 18

Water flowing back into the ocean at a right angle to the beach

Question 19

What are the three types of chemical weathering

Answer 19

Carbonation
Hydrolysis
Oxidation

Question 20

What is Carbonation

Answer 20

Carbonic acid in rain water reacts with calcium carbonate so limestone carried away in solution

Question 21

What is Hydrolysis

Answer 21

When acidic rain breaks down rock

Question 22

What is Oxidation

Answer 22

When rocks are broken down by oxygen and water

Question 23

What is Solution

Answer 23

When there is a change in chemical composition of the rocks

Question 24

What are the two types of mechanical (physical) weathering

Answer 24

Freeze-thaw

Salt weathering

Question 25

What is Freeze-thaw

Answer 25

Happens when water enters crack, freezes and expands putting pressure on rock. when melts, pressure relieved. continuous process leads to rock breaking

Question 26

What is Salt weathering

Answer 26

When salt from sea gets in cracks, may evaporate and crystallize putting pressure on rock and weakening structure

Question 27

What is biological weathering

Answer 27

As plant roots grow, they expand and push rock apart

Question 28

Why is sediment deposited in coastal areas

Answer 28

When waves enter shallower water/sheltered water When there's little wind When there's a good supply of material

Question 29

What's a concordant coastline

Answer 29

Where the type of rock stays the same along the coastline. Tend to have fewer bays and headlands

Question 30

What's a disconcordant coastline

Answer 30

Where the geology alternates between strata (or bands) of hard and soft rock

Question 31

How are headlands and bays formed

Answer 31

Hard (chalk) and soft (clay, sand, glacial till) rock Bays form due to rapid erosion of softer rock Headland left sticking out as resistant to erosion

Question 32

What happens to the headlands and bays once they are formed

Answer 32

Bay becomes sheltered by headlands so less eroded | Headland left more vulnerable to erosion and wave energy is concentrated here

Question 33

How are cliffs formed

Answer 33

between high and low tide rocks hurled at base of cliff- corrosion creates wave-cut notch and top of cliff becomes unstable overhang will collapse into the sea leaving a cliff

Question 34

How are wavecut platforms formed

Answer 34

Material broken off from headland means more material for corrasion so the process will continue. because there is no erosion below low tide, wave-cut platform is left.

Question 35

How is a cave formed

Answer 35

Small lines of weakness in rocks. hydraulic action - crack widens causing small cave in headland increased headland erosion due to wave refraction Over time attrition, abrasion etc. causes cave deeper and wider

Question 36

How is an arch formed

Answer 36

Process of cave continues to happen until eroded all the way through forming an arch

Question 37

How are stacks and stumps formed

Answer 37

Arch weakened , by weathering so will collapse leaving a stack in its place. this will eventually form a stump

Question 38

What is a spit

Answer 38

Long finger of sand or shingle jetting out into the sea from the land

Question 39

How are spits formed

Answer 39

Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift.

Question 40

How are bars formed

Answer 40

When the spit meets a bay it continues from one headland to another forming a bar. where the old bay was is now a lagoon which will eventually be filled by deposition

Question 41

What is a beach

Answer 41

Areas of deposited sediment- sand and shingle which have been deposited as currents and longshore drift have lost energy

Question 42

Gradient, dominant waves, distance stretches back, back of beach of sandy beach

Answer 42

shallow almost flat, constructive, a long way, sometimes sand dunes

Question 43

Other characteristics of a sandy beach

Answer 43

At low tide water fills depressions called runnels form. these are separated by small sandy ridges running parallel to the shore

Question 44

Gradient, dominant waves, distance stretches back, back of beach of pebble beaches

Answer 44

Generally steep, destructive, not far, storm beach with large pebbles

Question 45

Other characteristics of a pebble beach

Answer 45

Pebbles increase in size towards the back of the beach

Question 46

What's a berm

Answer 46

A terrace on a beach that's formed in the backshore above the water level at high tide formed in calm weather when constructive waves transport material onto the beach

Question 47

What is needed for dune formation

Answer 47

Large flat beach with large sand supply large tidal range onshore wind obstacle (drift wood or litter)

Question 48

How are sand dunes formed

Answer 48

Wind blows sand and collects around obstacle forming embryo dunes dunes begin to stabilise as colonised with plants holding the dunes together these produce fore dunes and eventually yellow dunes

Question 49

What happens over time with the yellow dunes

Answer 49

Rotting organic material makes sand more fertile allowing range of vegetation to exist wind can form depressions where sands removed from dune, exposing water table below forming ponds called blowouts mature dunes eventually form with more complex vegetation found