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coasts Flashcards

1
Q

compare constructive and destructive waves in terms of physical appearance

A

constructive: larger wavelength and smaller amplitude
destructive: smaller wavelength and bigger amplitude

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2
Q

compare constructive and destructive waves in terms of swash and backwash

A

constructive: powerful swash, weak backwash
destructive: powerful backwash, weak swash

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3
Q

how and when do constructive waves form

A

formed by storms often hundreds of kilometres away
common in summer

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4
Q

how and when do destructive waves form

A

formed by local storms close to the coast
common in winter

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5
Q

what are the three types of weathering with basic descriptions

A

mechanical - disintegration of rock
chemical - chemical changes
biological - actions of flora and fauna

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6
Q

description of example of mechanical weathering

A

freeze thaw
water collects in cracks of rock and expands as it freezes. cracks and collects as scree at foot

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7
Q

description of example of chemical weathering

A

carbonation
rainwater is slightly acidic because it absorbs co2. contact with alkaline rocks e.g limestone causes slow dissolve

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8
Q

description of example of biological weathering

A

plant roots and animals burrow into weak rocks/sand

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9
Q

what is mass movement and three examples

A

downward movement of material under influence of gravity
sliding, slumping, rockfall

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10
Q

what is sliding

A

rock sliding down the slide plane of a cliff due to rainfall or an earthquake

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11
Q

what is slumping

A

collapse of saturated/weak rocks along curved slip plane (scarp) due to unstable base

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12
Q

what is rockfall

A

rocks falling down cliff face due to freeze thaw. collects as scree

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13
Q

what is hydraulic action

A

power of waves and air that gets trapped by them causes erosion

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14
Q

what is abrasion

A

sandpapering effect of rocks against rocky platform

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15
Q

what is attrition

A

rocks knocking against each other and becoming smaller/more rounded.
does not contribute to coastal erosion

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16
Q

what is solution (transportation)

A

dissolved chemicals from limestone or chalk

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17
Q

what is suspension

A

particles carried within water

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18
Q

what is traction

A

large pebbles rolled along sea bed

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19
Q

what is saltation

A

bouncing motion of particles too heavy to suspend

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20
Q

what geological structure is required for headlands and bays

A

discordant coastline: bands of stronger and weaker rock perpendicular from the coastline

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21
Q

how do headlands and bays form

A

on discordant coastline, weaker rock erodes faster (bay). sheltered and low energy waves - deposition.
harder rock sticks out (headland). high energy waves - wcn & no deposition

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22
Q

how do caves form and which erosion/weathering processes occur

A

weaknesses e.g faults or joints in cliff face start to erode.
ABRASION AND HYDRAULIC ACTION

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23
Q

how do arches form and which erosion/weathering processes occur

A

back to back caves connect
ABRASION AND HYDRAULIC ACTION

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24
Q

how do stacks form and which erosion/weathering processes occur

A

roof of arch is weakened and collapses
WEATHERING PROCESSES

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25
how do stumps form and which erosion/weathering processes occur
wave cut notches form at bottom of stack and collapses HYDRAULIC ACTION
26
how do faults form in cliffs
hydraulic action
27
what is a wave cut notch
hydraulic action and abrasion processes between the high and low wave zones erode the base. material removed by destructive waves. notch formed
28
why do cliffs retreat
once wcn become to large for the overhanging cliff to defy gravity, it falls onto the beach, aided by weathering. processes repeats
29
what is a wave cut platform
former base of cliff is left. continuously smoothed by abrasion.
30
features of a sandy beach
shallow and flatter low energy constructive waves wider sometimes dunes at back strong swash
31
features of pebble beach
steep profile destructive waves not wide larger pebbles at back stronger backwash
32
why do beach profiles change
berms (ridges of sand caused by deposition in calm weather) are moved up beach by storms and spring tides. in winter, berms dragged down beach, forming offshore bars, lowering beach.
33
how are dunes formed
• embryo dunes form around obstacles • develop and stabilise by vegetation, eg marram grass, forms fore dunes • rotting vegetation makes sand fertile and creates wider range of plants • wind can form depressions called dune slacks, in which ponds form
34
how do spits form
* on coastlines with longshored drift, if coastline bends sharply, sediment continues to be pushed in same direction, out to sea * changes in strong winds and waves can curve spit (recurved end) * may be multiple from previous positions of spit
35
how do saltmarshes form
the area behind spit is sheltered. mud is deposited and causes vegetation. these are vital wildlife habitats
36
what is a bar
when spits grow across a bay. freshwater lagoon trapped behind it
37
three advantages of sea walls
• very effectively deflects wave energy, preventing erosion & flooding • provides promenade in seaside town • long lasting
38
three disadvantages of sea walls
• unattractive and unnatural • £5000 per metre and high maintenance • restrict access to beach
39
how do groynes prevent erosion and what are some advantages
prevents longshore drift, keeping natural defence of beach * wider beach - popular with tourists * useful structures eg fishing, windbreakers * less expensive, 750 per m
40
two disadvantages of groynes
• terminal groyne syndrome - interruption of longshore drift deprives beach further down - increasing erosion elsewhere • unnatural & unattractive
41
how does rock armour prevent erosion and what are the advantages
absorbs wave energy * relatively cheap, 2 000 per m * useful structures eg fishing, climbing, sunbathing - long lasting
42
two disadvantages of rock armour
* expensive to transport rock * rocks from elsewehere - doesn’t fit into local geology - obtrusive
43
how do gabions prevent erosion and what are the advantages
absorb wave energy * cheap, 500 per m * can become vegetated and merge into landscape * even if cages erode, rocks inside form makeshift body armour
44
disadvantages of gabions
* unnatural and unattractive when first built * cages only last 5-10 years
45
what is beach nourishment/re profiling?
adding local sand or shingle to existing beach to heighten or widen it
46
two advantages of beach nourishment / re profiling
• increases tourist potential • added shingle blends into beach
47
two disadvantages of beach nourishment/reprofiling
would not be effective on coastlines with longshort drift - hard engineering would be needed (groynes) * 500 000 per 100m
48
what is dune regeneration/fencing
using dunes as buffers to sea, preserving them using marram grass and fences
49
two advantages of dune regeneration
* habitat to rare bird, reptile, and dragon/damsel fly species * cheap, little as 400 per 100m fencing
50
three disadvantages of dune regeneration
* people do not always respond well to being prohibited from natural areas - storms damage and make them look unattractive
51
what is managed retreat
deliberately allowing sea to flood or erode area of low value land
52
three advantages if managed retreat
• more sustainable than spending money and effort on building and maintaining defences • soft engineering • important for future as seas rise
53
disadvantages of managed retreat/ do nothing
• people may be rehoused
54
what is no active intervention
no plans for defences
55
what is hold the line
maintain current defences
56
what is advance the line
increase defences to extend coastline
57
where is medmerry
south coast of uk in west sussex
58
why was management needed in medmerry
• 300 homes, waterworks and roads • constant heavy machinery work on beach
59
what were the objectives of medmerry
• create natural saltmarsh (natural buffer to sea) • protect surrounding farmland and caravan parks from flooding • create intertidal wildlife habitat and encourage visitors to sea o
60
description of scheme and things needed for medmerry
• 7 km of banks • 450 000 tonnes of clay • 60 000 tonnes or rock, just to barricade ends • ditches created to encourage ponds
61
6 advantages of medmerry
• leisure • habitats • natural buffer for erosion • protects local towns & industry • investment: no maintaining defences • salt in wanter gives grazing cows desirable taste
62
3 disadvantages of medmerry
• 28 million • loss of farmland • hard engineering still required
63
where is lyme regis
small coastal town, south coast of england
64
reasons for management in lyme regis
• built on unstable cliffs • fastest eroding cliffs in all if europe • sea wall breached many times, damaging property
65
aims of management in lyne regis
• long term protection • no controversy as public informed and meetings held
66
phase 1 and 2: 4 key features of lyme regis scheme
• new sea walls and promenades • rock armour extended • sand dredged from english channel for nourishment • £1.4 million for cliff stabilisation: hundred of nails hold rocks tg
67
phase 4 lyme regis
• 340m sea wall in front of existing wall • further cliff stabilisation to protect 480 homes
68
phase 3 lyme regis
proposed to prevent landslips costs outweighed benefits
69
3 advantages of lyme regis scheme
• new beaches = tourism • new defences have withstood recent stormy winters • harbour protected, benefitting fishermen and boat owners
70
3 disadvantages of lyme regis scheme
* tourism led to litter and congestion - £43 million * natural landscape spoiled
71
2 disadvantages of lyme regis scheme
• tourism led to litter and congestion • natural landscape spoiled

gcse geog (10 decks)

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