Coastal landscapes (P1- SEC C) Flashcards

(39 cards)

1
Q

what are constructive waves?

A

LOW WAVES and LONG WAVELENGTH that surge up the beach and ‘spill’ with POWERFUL SWASH.
- carries/deposits large amounts of pebbles/sand to CONSTRUCT THE BEACH

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2
Q

what are destructive waves?

A

Formed by local storms close to coast
CLOSELY SPACED
HIGH/STEEP WAVES that PLUNGE INTO BEACH
LITTLE SWASH but POWERFUL BACKWASH - removes sand/pebbles so ‘destroys’ it

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3
Q

what is the FETCH?

A

how far the wave has travelled

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4
Q

attrition?

A

rock fragment carried by the sea knock against each other causing small/more rounded rocks.

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5
Q

abrasion?

A

‘sandpapering’ effect on pebbles grinding over a rocky platform - becomes smooth

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6
Q

solution?

A

dissolving of soluble chemicals in rocks

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7
Q

corrasion?

A

fragments of rocks are picked up/hurled by the sea at a cliff.
the rocks erode the cliff

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8
Q

hydraulic power?

A

POWER of waves as they smash onto the cliff. trapped air is forced into cracks In rocks making them break - cavitation

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9
Q

5 main processes that influence shape of the coastline?

A

EROSION
WEATHERING
MASS MOVEMENT
TRANSPORTATION
DEPOSITION

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10
Q

weathering?

A

weakening or decay of rocks in their original place on, or close to , the ground surface

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11
Q

2 types of physical weathering and explain?

A

freeze thaw - water collects in cracks of rock and freezes/expands making cracks bigger
- when temps rise, ice thaws , water seeps deeper into rocks
REPEAT - THEY BREAK

Salt weathering - seawater evaporates leaving CRYSTALS
- they grow/expand
- put pressure on rocks /breaks

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12
Q

chemical weathering ?

A

rainwater absorbs co2 from air and becomes acidic
- contact with alkaline rocks causes CHEMICAL REACTION , so rocks DISSOLVE

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13
Q

mass movement ?

A

downward movement or sliding of material under influence of gravity

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14
Q

types of mass movement?

A

ROCKFALL - rocks break away from cliff face often due to free thaw weathering
ROTATIONAL SLIP- slump of saturated soil/weak rock along a CURVED surface
MUDFLOW- saturated soil/weak rock flow down a slope
LANDSLIDE - blocks of rock slide downhill

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15
Q

coastal transportation - 4 ways ?

A

solution ; dissolved chemicals from limestone and chalk
suspension: particles carried in water
traction ; large pebbles rolled along a seabed
saltation ; a ‘bouncing’ motion of particles too heavy to be suspended

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16
Q

describe and explain the process of longshore drift?

A
  • process where waves transport material
    -the swash moves material up the beach at an angle
  • the material the moves back at 90 degrees due to gravity
  • this movement carries on along the beach in a zig-zag motion
17
Q

what types of rock form bay and headlands?

A

weaker rocks erode to FORM BAYS
tougher rocks erode SLOWER to form HEADLANDS

18
Q

How do wave cut notches and platforms form?

A

when sea attacks base of cliff, erosion wears away the cliff at the base forming WAVE CUT NOTCH

overtime the notch gets DEEPER by corrasion, hydraulic action, abrasion /UNDERCUTS THE CLIFF - eventually the overlaying cliff can supports its weight/collapses
- as sequence continues cliff retreats and form a gentle sloping platform - WAVE CUT PLATFORM

19
Q

how are caves , arches and stacks formed?

A
  • crack in headland made larger by hydraulic action AND GROWS INTO CAVE
  • cave breaks though headland forming arch
  • base of arch becomes Widder and thinner through erosion and weathering/ roof of arch collapses leaving stack
20
Q

how do beaches form?

A

DEPOSITION OF SAND /SHINGLE
- waves are constructive
- pebble beaches formed by high energy environments as they wash away fine sand and leave large pebbles

21
Q

how do sand dunes form?

A

SAND DEPOSITED on th beach and blown INLAND by wind to form dunes.
- stabilised by vegetation to form FORE DUNES/YELLOW DUNES

22
Q

HOW DO SPITS FORM?

A
  • forms where there is ALOT of LONGSHORE DRIFT , where coastline suddenly changes shape
  • SEDIMENT DEPOSITS out to sea and builds up - forms EXTENSION OF LAND
  • this continues making it more extended until water becomes too deep
  • strong winds /tidal currents causes CURVED END SPIT
23
Q

HOW DO BARS FORM?

A

longshore drift can cause SPIT to grow ACROSS A BAY! - TRAPS LAKES BEHIND IT -BAR

24
Q

CASE STUDY : SWANAGE , location , landforms

A

Seaside town in DORSET , SOUTH COAST OF UK
-located in a sheltered bay/broad sandy beach , between 2 headlands
SWANAGE BAY - because sand and chalk between the two bands of hard resistant rock erodes at a ​faster rate​.

N of swanage - POOLE HARBOUR
- increased DEPOSITION at mouth of several rivers
- formed large esturary/salt marsh

25
why do coasts need to be managed?
MAINTAIN balance between forces of nature and demands of people
26
what are 3 management strategies ?
HARD ENGINEERING - use artificial structures to control natural processes SOFT ENGINEERING - less intrusive, envrironmentally friendly method that wrks with natural processes MANAGED RETREAT- allowing the sea to flood over low lying land
27
HARD ENGINEERING - GROYNES ad and dis
TIMBER /rock structures built out to sea from the coast - trap sediment/enlarge beach - wider beach is buffer to reduce wave damage - stop material being moved along beach by longshore drift , as sand builds up on updrift side AD : **wider beach** - tourism - provide useful structures for **fishing** - **not too expensive** DIS: - unattractive - deprives areas downwind of sediment, increasing erosion elsewhere
28
HARD ENGINEERING - SEA WALL AD/DIS
Concrete/rock barrier against the sea at foot of cliffs /at top the beach - absorb/deflect energy of waves back to sea AD : - effective - has walkway DIS : can look obtrusive/unnatural - expensive
29
HARD ENGINEERING - ROCK ARMOUR AD/DIS
Piles of large boulders dumped at foot of cliff. the rocks force waves to break , absorbing energy , protecting cliffs . - gaps between rocks , disperses energy of waves - decrease erosional power AD: cheap - used for fishing DIS : - rocks are from elsewhere so doesn't fit in with local geology - obtrusive
30
HARD ENGINEERING - GABIONS AD/DIS
wire cages filled with rocks to support a cliff/buffer against the sea AD : cheap improve cliff drainage DIS : look unattractive only last 5-10 yrs
31
SOFT ENGINEERING - BEACH NOURISHMENT AD/DIS
addition of sand /shingle to existing beach to make it higher water AD: cheap/easy to maintain blends in increase tourism DIS : needs contrast maintenance
32
what is reprofiling ?
- artificial reshaping of a beach using existing beach material.
33
SOFT ENGINEERING - DUNE REGENERATION AD/DIS
sand dunes buffer the sea . MARRAM GRASS is planted to stabilise dunes/help them develop AD : maintain natural environment - cheap DIS : planting is time consuming easily damaged in a storm
34
HARD ENGINEERING - REVETEMENTS AD/DIS
wooden and concrete ramps that helps absorb wave energy AD: Cost effective DIS : unattractive need constant maintainance
35
what is managed retreat?
deliberate policy of allowing the sea to flood or erode an area of relatively low land.
36
reasons for management , management strategies and the future of MEDMERRY MANAGED RETREAT?
REASONS : protected by LOW SEA WALL that needs repair /protect against rising sea levels STRATEGIES : allow the sea to breach sea defences /flood farmland cost : 28 mill in NOV 2013 FUTURE: - create a large natural saltmarsh - help protect surrounding farmland /caravan parks from flooding - establish wildlife habitat /encourage visitors
37
# example Lyme Regis - issues
- town is on UNSTABLE CLIFFS - coatsline eroding rapidly -> properties destroyed/damaged
38
# example Lyme Regis - how is it managed?
lyme Regis Envrionemental Improvement Scheme - **new sea wall/promenade** - - creation of **wide sand/shingle beach** - extension of **rock armour**
39
Lyme Regis - how successful was scheme?
**POSITIVE OUTCOMES** - have business thriving on seafront - defences withstand stormy winter - harbour is better protected **NEGATIVE OUTCOMES** - more visitors --> more conflict/traffic - defences spoil natural landscape