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A Level Physical Geog > Coasts 2 > Flashcards

Coasts 2 Flashcards

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1
Q

EROSIONAL LANDFORMS

strata - how is horizontal strata affect the shape

A
  • undercutting leads to riockfall
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2
Q

EROSIONAL LANDFORMS

strata - how is seaward sipping strata affect the shape

A
  • undercutting leads to undercutting which removes support, rock laters loosened by weathering and slide down
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3
Q

EROSIONAL LANDFORMS

strata - how is landward dipping strata affect the shape

A
  • undercurring leads to loosened rock thats difficult to dislodge, bot overtime slope profile is lowered by mass movement
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4
Q

EROSIONAL LANDFORMS

subarial processes include

A

weathering

freeze thaw
salt crystalisation
thermal expansion
chemical

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5
Q

EROSIONAL LANDFORMS

shore platforms
regular removal of debris at the foot of the cliff cause what

A

the cliff profile remains steep

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6
Q

EROSIONAL LANDFORMS

shore platform
process of shore platform

A
  • sea creates a wave sut notch
  • weathering occours at the top of the cliff, causing it to collapse
  • constructive waves transport material away reating a shore platform
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7
Q

EROSIONAL LANDFORMS

shpre platform
a level 4 points

A
  • sediment being dragged away causes erosion of shore platfrom
  • before this shore platform must reach width of 500m
  • solution occours due to algea releacing co2 at night time, means co2 in water = carbonation
  • between 0-3 degress, as wave levels are most consistant at high and low tide, so erosion is highest at these points leaving a low level ramp anf wave cut notch
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8
Q

EROSIONAL LANDFORMS

wave refraction
name of waves

A

orthogonals

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9
Q

EROSIONAL LANDFORMS
wave refraction
what happens to headlands

A
  • converging orthogonal waves concentrate on headlands, due to bein frefracted with hig energy = high erosion
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10
Q

EROSIONAL LANDFORMS
wave refraction
what happens energy

A

energy is dissipated for bays

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11
Q

EROSIONAL LANDFORMS
wave refraction
what happens to bays

A
  • bays have diverging orthogonal waves causing deposition due to low energy
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12
Q

EROSIONAL LANDFORMS

blow holes and geo

how are blow holes formed

A

splashing of waves englarges joints into a cave, air is trapped inside, overtime a natural shaft is formed when it breaks through surface

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13
Q

EROSIONAL LANDFORMS

blow holes and geo

how are geos formed

A

enlargement of blow holes weakens cave roof and overtime collapses

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14
Q

EROSIONAL LANDFORMS

blow holes and geo

3 a level points

A
  • starts at wave cut notch
  • hard rock - needs strength and structural integrity for caves and creeks
  • needs structural weaknesses ( complex ) to allow vertical erosion
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15
Q

DEPOSITIONAL LANDFORMS

where does deposition most commonly occur ( 5 )

A
  • when accumulation exceeds rate of removal
  • when waves slow immediately after braking
  • at the top of the wash when water is no longer moving
  • during backwash when water percolates into the beach
  • low energy sheltered areas
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16
Q

DEPOSITIONAL LANDFORMS

What’s settling velocity

A

The velocity at which particles are deposited - heavy first

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17
Q

DEPOSITIONAL LANDFORMS

How does a gentle gradient beach occur

A
  • Less then 5°
  • small particles become compact when wet
  • allows little perculation during backwash
  • little energy is lost to friction and little volume is lost during percolation = gentle gradient
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18
Q

DEPOSITIONAL LANDFORM

How does steep beaches occur

A
  • larger sediment
  • wash is stronger then backwash so there is a November of shingle on shore
  • makes the upper part of beach where rapid percolation occurs due to larger air spaces
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19
Q

DEPOSITIONAL LANDFORMS

Particle size and beach angles ( 2 )

A

Pebbles - 4mm. 17°

Medium sand - 0.2mm. 5

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20
Q

DEPOSITIONAL LANDFORMS

Beach features ( ripples, storm beach, runnels and cusps )

A

Ripples - loose sandy seabed is subject to wave action and ripple marks appear - TIDAL

Storm beach - accumulation of large sediment above high water mark due to storm action 1-100 YEARS

Runnels - with ridges being areas of raised beach, the dips are water filled troughs actin f as draining routes for tides TIDAL

Cusps - sand and gravel deposits in an arc patterned formed by wave patterns of converging currents TIDAL

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21
Q

DEPOSITIONAL LANDFORMS

Difference between summer beaches and winter beaches

A

Summer - more gradual slope due to smaller waves trying to replace sediment lost during winter

Winter - Steeper due to storm conditions

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22
Q

DEPOSITIONAL LANDFORMS

What’s a swash aligned beach

A

Beach breaking parallel to the shore = move member of sediment being up and down = Bay head beaches

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23
Q

DEPOSITIONAL LANDFORMS

What’s a drift aligned beach

A

Drift aligned beaches develop when waves approach at an angle, process of LSD

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24
Q

DEPOSITIONAL FEATURES

How do spits form and example

A
  • formed by LSD occurring on the dominant prevailing wind direction
  • sediment carried and deposited at low energy and shallow areas when settling velocity is reached
  • can be recited by change in wind direction
  • leeward side = salt marsh due to low energy

EG

Orford ness = east angkia
- north easterly winds dominant

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25
DEPOSITIONAL FEATURES how are bars formed and example
- Low energy environment, shallow area, settling velocity reached = deposition EXAMPLE Spurn head = Humber estuary
26
DEPOSITIONAL FEATURES How are tombolos formed and example
- accretion of sand at the Lee of the island = low energy - formed via wave refraction due to shallow water - Convergence of LSD = meets around island at Lee = settling velocity reached EXAMPLE St ninans = Shetland
27
DEPOSITIONAL FEATURES chelsil beach 1st theory
LSD
28
DEPOSITIONAL FEATURES CHESIL BEACH 2nd theory
- last glacial period = sea was 120m lower - many rivers flowing from mainland - barrier island formed via fluvial deposits - sea levels rise after glacial period - barrier island is forced to migrate and is now wedged where it is
29
DEPOSITIONAL FEATURES Evidence for 2nd theory of chesil beach
- When barrier island formed - sediment is evenly distributed - when it moved the primary LSD transported all sediment south - secondary weaker LSD transported smaller sediment north CHESIL BEACH HAS SMALL SEDIMENT FIRST = unusual as it’s always LARGE - SMALL
30
EAST YORKSHIRE COASTLINE geology of FH, SB,FBrigg
hard lithology - chalk and limestone complex structure - bedding planes and faults
31
EAST YORKSHIRE COASTLINE FH, SB,FBrigg - rate of erosion
0.1m/year
32
EAST YORKSHIRE COASTLINE FH, SB,FBrigg, common mass movement ?
rockfall
33
EAST YORKSHIRE COASTLINE what type of coastline and what does this cause
disconcordant = differental erosion
34
EAST YORKSHIRE COASTLINE RHB,FB, - geology
soft lithology = sandstone, mudstone and clay complex lithology = bedding planes and faults
35
EAST YORKSHIRE COASTLINE Rate of erosion for RHB,FB
0.8m/year
36
EAST YORKSHIRE COASTLINE RHB,FB type of mass movement
slumping = rock permeable
37
EAST YORKSHIRE COASTLINE Physical factors ( wind )
0-gale force = frictional drag imparting energy onto waves over a long period of time due to 1500km fetch 50kg/cm2 of pressure
38
EAST YORKSHIRE COASTLINE physical factors ( tide )
neap tide 4.8m ebbing tide 6.1 - salt crystalisation
39
EAST YORKSHIRE COASTLINE physical factors ( temp )
- rarely below freezing, not to hot - rarely freeze thaw and chemical weathering - storm cause destruction
40
EAST YORKSHIRE COASTLINE F head north side
- waves concentrated - erosional features due to marine actlivites
41
EAST YORKSHIRE COASTLINE F head south side
- waves disperced - depositional featers eg: north shore beach - lower setting velocity and more constructive waves
42
EAST YORKSHIRE COASTLINE inter relationships
physical factors - geomorphic processes - coastal features
43
EAST YORKSHIRE COASTLINE temporal features
tide - daily - beaches 100s of years - equilibrium regained after storm Bech after years - seasonal changes = more destructive waves in winter - mass movemnt is seconds
44
EAST YORKSHIRE COASTLINE example of mass movement
- holbeck hall landslide example - 60m of glacial till lost overnight = soft rock
45
NILE DELTA Why did they build the Aswan high dam and the affects
- natural floods leaving silts = fertile ground - built yhe dam to control the flooding because more floods = more agriculture - traps 98% of sediment = impacts dynamic equilibrium - lake nassa behind = sediment deposited sue to low energy environment = less sediment in delta = more erosional
46
NILE DELTA Key facts
6650km long 4.26 t/ha/y = sediment input Originates in Ethiopia
47
NILE DELTA - physical factors Waves
- short fetch, enclosed sea, higher wave height by 1m in winter = constructive waves - LSD occurs pulling sediment creating smaller scale drift aligned features which make up front of delta
48
NILE DELTA - physical factors Wind
NW wind 10mph , higher in winter W-E sediment drift Aeolian brings sediment from ly Ian desserts
49
NILE DELTA - physical factors Geology
- Delta made up of soft lithology ( alluvial silts ) - limestone ridges on Alexandra = formation of Abu quir headland and bay
50
NILE DELTA - physical factors Tides
- Very low tidal rand which is important for delta formation - low tidal range as most sediment is brung in via fluvial inputs
51
NILE DELTA - physical factors Ocean currents
Very insignificant but help LSD Now more significant due to less sediment output from fluvial sources = more sediment from lybia
52
NILE DELTA - physical factors Sea level rise
10-15 cm rise has meant a 10-15m retreat If sea level rises 1m it’s predicted that 15% of the delta will be lost Sea level rises means: increased energy, wave height and tidal range. More marine processes changing it from depositional to erosional
53
NILE DELTA - Features Rosetta and Damietta promentry
- deposition due to flocculations when clay hit the Mediterranean - NW wind = exposed to strinf destructive waves = sediment imput - the sediment is dragged along the edge of delta and deposited in the low energy environments = spits and drift aligned features - now overall more of an erosional environment due to lack of sediment
54
NILE DELTA - Features Bulurus and manzala lagoon
- LSD and ocean currents move sediment W-E due to NW wind - sediment moved to delta front = deposition in low energy environments -lagoons getting smaller due to bars preventing the lagoons access to sea, therefore evaporation due to hot environment - increases erosion = lack of sediment
55
NILE DELTA - Features Abu quir headland and bay
- limestone ridges = headland and soft rock = bay - differential erosion and diverging waves
56
NILE DELTA - Features Sand dunes
- onshore winds blowing sediment - aeolian transport from neighbouring sediment
57
DEPOSITIONAL FEATURES SALT MARSH where do they form what conditions needed for formation
- low energy environments eg: estuarys - little wave action, shelter from exposure, source of sediment
58
DEPOSITIONAL FEATURES SALT MARSH formation
- clay particles arrive through fluvail imputs via suspension - only 0.05mm so too light to settle, flocculation occours where the electrical charge from clay is wiped by sea water, therefore can clump together and settle
59
DEPOSITIONAL FEATURES SALT MARSH zonation and sucession
- zonation is a spatial pattern, different species have different abiotic factors and are loacted in areas where they can withstand salt - halophytes are in lower areas as they are reguarly submerged due to having a high tolerance - sucession is when a new species emerges, this occours at areas with little salt tolerance due to large competion
60
DEPOSITIONAL FEATURES SALT MARSH factors affecting
- changes in wave size can alter marsh stability - chnages in tides alter species location ( zonation ) - costal squeeze - as its a dynamic environment when the sea levels rise the marsh moves to accomodate for species with a low salt tolerance, if hard engineeding occours it cant migrate = costal squeeze
61
DEPOSITIONAL FEATURES Deltas what are they
- formed when rivers empty their water and sediment into an alternate body of water - occours in low energy environments with a large sediment load
62
DEPOSITIONAL FEATURES Deltas distributaries levees crevasse spray
distributaries - branch of into smaller streams levees - these are built up areas of sediment surrounding distributaries crevasse cpray - fluvial deposits when a levee breaks
63
DEPOSITIONAL FEATURES Deltas 3 types
cuspate delta = pointed extension when sediment accumulates due to alternating gentle currents eg : timber river in Rome arcuate delta = sufficient sediment supply, grows seawards eg: nile delta Birds foot delta - distributaries not reaching coast due to sediment supply being more then sediment removal

A Level Physical Geog (8 decks)

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