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Changing Places > coasts > Flashcards

coasts Flashcards

1
Q

wave formation

A

energy transferred from air to water, shelving increases friction, wave breaks

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2
Q

coastal defences effect on physical geo.

A

disrupt physical geography processes, e.g. walls, groynes

waves change direction, energy taken elsewhere

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3
Q

littoral zone and subdivisions

A

offshore (furtherest) - sea away from land
nearshore
foreshore
backshore (closest) - waves only reach during high tide
coast/land

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4
Q

primary coast

A

dominated by land-based processes
e.g. deposition from rivers, volcanic lava
zavodovski island

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5
Q

secondary coast

A

dominated by marine erosion / deposition

e.g. slapton

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6
Q

coastline morphodynamics

A

things that change a beach are constantly changing, the way different factors make a coastline unique and how these factors are constantly changing.

short term processes: rivers, waves, tides
longer term processes: geology, sea level change

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7
Q

wave size

A

wind strength
wind duration
water depth
wave direction

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8
Q

percolation

A

downward movement of water through soil, sand, pebbles

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9
Q

constructive

A 
low height, low wavelength 
6-8 per min
uninterrupted swash, nearshore
strong swash
steeper beach 
gradient change over long distance
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10
Q

destructive

A 
high height, short wavelength 
13-15 per min
slower waves approach steep beach 
still circular motion
stronger backwash 
gradient change over short distance
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11
Q

littoral zone

A

near shore area where sunlight penetrates sediments, allowing for aquatic life to flourish, but faces continuous change

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12
Q

sea-level change

A

geology of cork coastline:
orientated 90 degrees perp., alternating hard/soft rock = elongated narrow bays
hard resistant areas = detached islands

storms = long fetch, help rivers erode = form valleys

sea level rise = valleys drowned
headland + bay = exaggerated

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13
Q

role of wave refraction

A

deep water wave crests - parallel to the coastline
headlands: wave crests curve, refract, concentrated on headlands, spread outwards to the bays
headlands - accelerate erosion
material - deposited in bay
coastline: straight overall. headlands erode, material deposited in bays

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14
Q

tectonic activity on beach shape

A

push sedimentary rock up from seabed - e.g. limestone
can fold them - plate collisions = creates weak points for waves to exploit
magma may have risen to the surface and cooled = igneous rock
sea removes layers above it
igneous rock exposed and resisting wave erosion

= gradually get a straight coastline

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15
Q

rias

A

drowned river valley due to SLR

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16
Q

dalmatia coastline

A

concordant coastline
drowned by SLR
limestone geology
horizontal strata - oldest at bottom, youngest at top
tectonics - compressed and folded layers - anticlines and synclines
sub-aerial erosion - eroded starta in weak places
rivers erode synclines
long narrow islands are left

17
Q

haff coastline

A

long sediment ridges
sand dunes
parallel to coastline
series of lagoons between ridges and shores

18
Q

marine erosion

A

synclines, beneath

19
Q

river erosion

A

anticlines and shapes landscape

20
Q

new zealand

A

convergent plate boundary
7.8 magnitude wave - 4 different faults broke at once
sea bed is now 2m higher
marine animals died
3km/second
6m uplift on one side, 2m uplift on other
new foreshore

21
Q

isostatic change

A

heavy ice pushes land downwards, melting ice means that land rebounds back
new cliffs formed through erosion, old fossil cliffs remain

22
Q

isostatic readjustment

A

soft vicious mantle, parts of crust respond to change

23
Q

norwegian fjords

A

submergent coastline as a result of eustatic SLR
200km inland
fracture system in bedrock
entrance at seaward end is shalower
gravel and sand deposits = made certain areas of fjords shallower

24
Q

wave-cut platform

A

sloping rocky shelf found at the foot of a retreating cliff and exposed at low tide

25
Q

periglacial

A

permanently frozen ground

26
Q

fjords

A

submerged u-shaped valley that has been over-deepened inland
rock lip threshold - seaward entrance

27
Q

eustatic rise/fall

A

change in global sea level

28
Q

Louisiana

A

Mississippi river flows into Gulf of Mexico
depositional coast - marshes, swamps, barrier islands
huge levees and engineering projects to protect NO
vulnerable to storm surges, global sea level rise, isostatic tectonic uplift

29
Q

eustatic fall

A

ice sheets formed during glacial period

evaporated water locked up as ice

30
Q

fall in SLR

A 
offshore bars 
raised beaches
fossil cliffs 
but...
storm surges? tides? tectonics?
31
Q

sea level changes daily

A

high and low tides alter local sea level
atmospheric air pressure = low pressure, slight rise
winds = wave height varies

32
Q

marine regression

A

eustatic fall and isostatic fall - former seabed exposed = emergent coast

33
Q

marine transgression

A

eustatic ride and isostatic rise - areas of land flood = submergent coast

34
Q

North Antrim Coast rock types

A

igneous: (impermeable)
basalt, dolerite and gabbro, granite, basalt
strong, hard erosion-resistant rock
few joints, limited weaknesses, erosion can’t exploit

sedimentary:
layers of rock formed over time 
sandstone (permeable)
animals and plants 
moderate/fast erosion rate 
young rocks = weaker 
shale - most vulnerable

metamorphic: (impermeable)
intense heat/pressure
slate, schist, marble
resistant to erosion
foliation - crystals in one direction = weakness
folded + heavily fractures
folding = cracks, water gets in, permeable

ancient limestone(permeable): more resistant 
recently erupted volcanic lava = weaker, easily eroded

permeability = groundwater flow weakens rocks, exploiting joints and structure, binding materials
high pore water pressures within cliff = reduce stability

low seaward dip but places with landward dip

35
Q

entablature

A

unconsolidated laterite, more permeable, stores water
water sits
water builds up in entablature as it travels slowly in the colonnades, so gets heavier and rock materials fall = mass movement

36
Q

colonnades

A

columns, water goes down cracks and faults

water can get through but very slowly

37
Q

West Africa (Guinea)

A

700m of erosion
10cm of SLR since 1950
1m SLR by 2100
urbanisation high along coast: fishing, tourism
stormy months
loss of mangrove forests: harvested as fuel wood
rainfall
intensive sand mining in mangroves and rivers
gold and diamond mining along rivers, gravel extracted from rivers each day but not returned
use gravel to build local houses
sand = removed from coastlines for construction
sea walls = too expensive
don’t do beach nourishment
major storms
local construction: seawalls and revetments stop sediments being moved along coast
tourist resorts = swept away
saltwater intrusion - destroying marine habitats
beach dunes reduced
natural vegetation removed or dislodged
steep cliffs - from weathering/undercutting

38
Q

Holderness

A

holderness coast
50 properties
access road
soft boulder clay cliffs
1-2m/ year rate of erosion
coastal management scheme: £2million
2 types of hard engineering: Norwegian granite rock armour along base of cliff
two rock groynes
stopped beach material being moved south along the coast
left area south of coast: Withensea unprotected
increased erosion in south
mappleton and cliffs no longer at great risk

39
Q

Trinidad and Tobago

A

small island, developing state
low lying, susceptible to 0.06m/year rise in SL
70% population live/work on coast
winter storms from Atlantic= higher swell waves
southerly LSD, high erosion rates: Coco Bay
coastal flooding along 20km Manzanilla beach, cut off roots
weak sandstone + metamorphoc rock
there are vital sites of oil industry= main source of GDP and exports

economic losses:
3rd largest economy in America after US and Canada
dependent on petrochemicals - 40% GDP, 80% exports
natural gas pipelines
infrastructure loss
300m major road access destroyed due to strom 2014
luxury beach homes - £700k
400,000+ tourists
$5.8 million spent on rehabilitation work
engineering firms + academic expertise

social losses:
loss of coconut plantations, watermelon+ vegetable cash crop
transport access affected - can’t access oil industry/tourist
value of coastal homes = likely to decrease overtime
damage to existing hotel and tourist industry
some owners can afford a rubble war, some can’t - rich/poor divide

environmental loss:
damage to turtles that may encourage ecotourism
ecosystems can adapt - so small scale loss

lack of understanding with regards to beach dyanmics

Changing Places (2 decks)

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