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Geography > Year 11 Coasts > Flashcards

Year 11 Coasts Flashcards

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1
Q

Where are waves generally larger

A

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

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2
Q

How do waves break

A

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

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3
Q

Qualities of destructive waves

A

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

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4
Q

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

A

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

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5
Q

Qualities of constructive waves

A

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

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6
Q

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

A

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

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7
Q

Process of coastal erosion

1.

A

Hydraulic action

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

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8
Q

Process of coastal erosion

2.

A

Abrasion

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

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9
Q

Process of coastal erosion

3.

A

Attrition

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

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10
Q

Process of coastal erosion

4.

A

Solution

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

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11
Q

When does deposition occur

A

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

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12
Q

What is mass movement

A

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

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13
Q

What is rockfall

A

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

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14
Q

What is a landslide

A

Blocks of rock slide downhill

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15
Q

What is a mudflow

A

Saturated mud, soil and weak rock flow downhill

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16
Q

What is rotational slip

A

Slump of saturated soil and weak rock along curved surface

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17
Q

What’s fetch

A

Distance wave travels across open water

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18
Q

What is backwash

A

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

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19
Q

What are the three types of chemical weathering

A

Carbonation
Hydrolysis
Oxidation

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20
Q

What is Carbonation

A

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

21
Q

What is Hydrolysis

A

When acidic rain breaks down rock

22
Q

What is Oxidation

A

When rocks are broken down by oxygen and water

23
Q

What is Solution

A

When there is a change in chemical composition of the rocks

24
Q

What are the two types of mechanical (physical) weathering

A

Freeze-thaw

Salt weathering

25
Q

What is Freeze-thaw

A

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

26
Q

What is Salt weathering

A

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

27
Q

What is biological weathering

A

As plant roots grow, they expand and push rock apart

28
Q

Why is sediment deposited in coastal areas

A

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

29
Q

What’s a concordant coastline

A

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

30
Q

What’s a disconcordant coastline

A

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

31
Q

How are headlands and bays formed

A

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

32
Q

What happens to the headlands and bays once they are formed

A

Bay becomes sheltered by headlands so less eroded

Headland left more vulnerable to erosion and wave energy is concentrated here

33
Q

How are cliffs formed

A

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

34
Q

How are wavecut platforms formed

A

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.

35
Q

How is a cave formed

A

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

36
Q

How is an arch formed

A

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

37
Q

How are stacks and stumps formed

A

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

38
Q

What is a spit

A

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

39
Q

How are spits formed

A

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

40
Q

How are bars formed

A

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

41
Q

What is a beach

A

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

42
Q

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

A

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

43
Q

Other characteristics of a sandy beach

A

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

44
Q

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

A

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

45
Q

Other characteristics of a pebble beach

A

Pebbles increase in size towards the back of the beach

46
Q

What’s a berm

A

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

47
Q

What is needed for dune formation

A

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

48
Q

How are sand dunes formed

A

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

49
Q

What happens over time with the yellow dunes

A

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

Geography (16 decks)

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