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geography alevel > landforms > Flashcards

landforms Flashcards

1
Q

what is a beach

A

accumulation of sediment, they are important temporary stores within sediment cells

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2
Q

where do beaches form

A

between high and low water mark

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3
Q

what are beaches formed of

A

material from offshore sand bars, longshore drift, wind blown sand and mass movement

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4
Q

what 4 types of beach are there

A

shingle vs sand
swash vs drift

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5
Q

what is the difference between shingle vs sand beaches

A

shingle : high energy, steeper, 10-20 degrees
sand : low energy, sloping, 5 degrees

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6
Q

what is the difference between swash align and drift align beaches

A

swash : waves approach parallel, swash and backwash same angle

drift : waves approach at an angle, retreat perpendicular, creates a zig zag motion

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7
Q

what is a discordant coastline

A

alternating bands of rock at a right angle

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8
Q

what is a concordant coast line

A

alternating bands of rock parallel to the coastline

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9
Q

what is the process of caves, arches, stacks and stumps forming

A
  • wave action is concentrated on headlands (wave refraction) through erional processes cracks/faults are exploited
  • over time this creates a cave
  • where cave faces oncoming waves, force is applied directly to rear of cave forming a blow hole
  • over time further erosion breaks through to create an arch
  • weathering on top of the arch causes it to collapse making a stack
  • further erosion and weathering creates a stump
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10
Q

what factors are involved in the formation of caves, arches, stacks and stumps

A
  • high energy coastline, destructive waves
  • erosional processes
  • wave refraction
  • amount/severity of cracks and faults
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11
Q

example of cave, arch, stack and stump

A

Old Harry in Dorset

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12
Q

how are wave cut platforms formed

A
  • wave action concentrated at high tide line
  • over time creates a wave cut notch
  • weathering on top + further erosion of the hitch causes cliff to become unstable and collapse
  • leaves behind a wave cut platform
  • this process repeats
  • they are fairly smooth and flat due to abrasion
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13
Q

why do wave cut platforms rarely extend further than 500m

A

longer the platform the further the waves have to travel, waves will break earlier and won’t reach the cliff, erosion of the cliffs won’t occur

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14
Q

what are the factors involved in the formation of wave cut platforms

A
  • erosion
  • weathering
  • tides
  • geology
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15
Q

what are cusps

A

crescent shaped indents in the shape of the coastline

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16
Q

where are cusps formed

A

sand and shingle beaches, heavier sediment is dropped at the horns

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17
Q

how are cusps formed

A

waves hit horns and drop heavier sediment, curved sides channel incoming swash into the centre of the cusp which creates stronger backwash flowing out of the centre, deepening it

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18
Q

what is a berm

A

raised, wide flat area at the back of a beach

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19
Q

what are ridges, runnels and ripples

A

ridges are raised lines on the beach
runnels are depressions that form behind ridges
ripples are smaller versions of ridges and runnels

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20
Q

why do ridges, runnels and ripples form

A

due to tide action moving back and forth

21
Q

what are spits

A

long narrow ridges of deposited sediment that form where the coastline changes direction, typically over estuaries

22
Q

how do spits form

A

longshore drift

23
Q

where is the coarser sediment

A

proximal end

24
Q

where is the smaller lighter sediment

A

distal end

25
Q

what is a simple spit

A

has one recurved end, no minor spits

26
Q

what is an example of a simple spit

A

spurn head

27
Q

what is a complex spit

A

have multiple recurves, minor spits, show previous position of the spit

28
Q

what is an example of a complex spit

A

hurst point

29
Q

what factors effect the formation of a spit

A
  • low energy environment + constructive wavesfor deposition
  • prevailing wind creating drift align coast
  • geology
  • shape of coast has to change
30
Q

what is a barrier beach

A

accumulation of sediment that connects two headlands

31
Q

how do barrier beaches form

A

either when a spit extends across the bay or when glaciers melted and deposited sediment in the last ice age

32
Q

what is a tombolo

A

mound or ridge of sediment that connects the main land to and island

33
Q

how does a tombolo form

A

from wave refraction

34
Q

what is an example of a barrier beach

A

Slapton Ley

35
Q

what is an example of a tombolo

A

Angel Road, Japan

36
Q

what is a barrier island

A

offshore deposit of sediment

37
Q

where do barrier islands form

A

Usually in areas of low tidal ranges and gently sloping offshore coastlines

38
Q

how are barrier islands formed

A

when glaciers from the last ice age 18,000 years ago and deposited their sediment

39
Q

what may happen on barrier islands

A

may become vegetated

40
Q

how do sand dunes form

A
  • sand is initially trapped by obstacles (storm berm where drift wood is)
  • obstacles grow, slows wind further leading to more deposition
  • pioneer species grow such as marram grass
  • these stabilise the dunes
  • die and decompose providing nutrients for other species
  • climatic climax when mature trees grow such as oak
41
Q

what is the order of dunes

A

embryo, yellow, grey and mature

42
Q

how tall is an embryo dune

A

1m

43
Q

how tall is a yellow dune

A

5m

44
Q

how tall is a grey dune

A

8-10m

45
Q

what may form between dunes

A

dune slacks, where the water table is at surface, aquatic ecosystems may form

46
Q

where do mudflats/salt marshes form

A

sheltered areas/ low energy environments such as behind an estuary

47
Q

how do mudflats/salt marshes form

A
  • sediment builds up as velocity is low
  • flocculation = slow flowing water meets saline sea, clay particles join together, sink to bed of estuary
  • salt tolerant plants grow such as eelgrass
  • pioneer species grow such as cordgrass (halophyte)
    deposition continues, plants continue to grow + die
  • surface of marsh raises, submerged for shorter periods of time
  • mudflat becomes a salt mash
  • more comped flowering species like sea lavender establish
  • deposition continues
  • climax vegetation when marsh rises above level of spring high tide
48
Q

what is an offshore bar

A

submerged or partly exposed ridges of sand or coarse sediment created by waves and currents offshore of the coast

49
Q

what do offshore bars act as

A

sediment sink
absorb wave energy, less erosion

geography alevel (14 decks)

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