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Geography Y12 > Coasts theory > Flashcards

Coasts theory Flashcards

1
Q

% sediment supply from cliff erosion on beaches

A

typically 5%

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2
Q

What are Ridges

A

Slightly raised areas of sandy beaches that run parallel to the shore

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3
Q

What are runnels

A

small troughs (dips) filled with water that run parallel to the shore

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4
Q

Why steeper gradient of shingle beaches

A

More percolation of water to less backwash and more swash - net movement of sediment up the beach

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5
Q

What are storm beaches/ridges, why do they form

A

storm waves hurl pebbles/cobbles to the back of beaches

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6
Q

What are berms

A

smaller ridges that form at the mean high tide mark due to deposition at the top of the swash

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7
Q

What are cusps

A

Small, semi-circular depressions formed when multiple waves reach the same point with swash and backwash with the same power.

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8
Q

How are cusps enlarged

A

They are enlarged as cusps channel swash to the centre of the depression causing a powerful backwash pulling material out of the centre down the beach - enlarging depression

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9
Q

What are ripples

A

Small grooves in sandbed - develop due to the orbital motion of water in waves that picks up and deposits sand grains, forming small troughs/grooves

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10
Q

Winter beaches

A

Increased high energy destructive waves caused increased movement of sediment offshore due to erosion, flattening the beach profile. This causes shallower water, increased friction and less wave energy (moving towards summer)

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11
Q

Summer beaches

A

Increased low energy constructive waves meaning increased sediment moving onshore with deposition. This steepens the beach profile. Causes deeper water, less friction and more wave energy - moving towards winter

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12
Q

When do waves break

A

When water depth is less than 1.3X wave height

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13
Q

3 main flows of energy

A

Kinetic, solar/thermal, gravitational

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14
Q

What are sediment cells

A

Closed system in which sediment in sourced stored and transferred between stores.

a linked system of sources, transfers and sinks of sediment along a section of coastline

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15
Q

How many sediment cells in the UK

A

11

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16
Q

Are sediment cells truly closed systems

A

No, small volumes of sediment escape to neighbouring cells during storm events, usually fine sediment like silt/clay

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17
Q

What is dynamic equilibrium of sediment

A

where input, outputs and flows of sediment are in a constant state of change but ​remain in balance​

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18
Q

Name the 3 processes of a coastal system

A

Erosion, transportation, deposition

19
Q

Name types of sediment transportation

A

Marine - traction, saltation, suspension, solution
Aeolian - same not solution

20
Q

Types of sediment transfers

A

Longshore drift
Swash
Backwash
Tidal currents
Sea/ocean currents
Wind (onshore, offshore or along shore)

21
Q

Impact of oblique winds

A

LSD

22
Q

What comes under structure of rocks (geology)

A

Concordant/discordant
Bedding planes and jointing - landward/seaward/horizontal strata
Fissures and faults - megafaults cause geos and blowholes

23
Q

3 types of breaking waves

A

Spilling - steep wave, gentle slope - usually constructive
Plunging - sudden depth change and steep wave - usually destructive
Surging - low wave + steep beach - large backwash - destructive

24
Q

% sediment supply from offshore on beaches

A

typically 5%

25
Q

% sediment supply from rivers on beaches

A

typically 90%

26
Q

neap tides

A

small tidal range, sun and moon not aligned

27
Q

spring tides

A

large tidal range, sun and moon aligned

28
Q

drift aligned beaches

A

waves at angle to coast, lsd moves sediment along beach

29
Q

swash aligned beaches

A

low energy environment (bays), waves parallel to shore

30
Q

emergent

A

eg. raised beach, marine terrace, relict cliff
eustatic = sea levels decrease
isostatic = land level increase

31
Q

submergent

A

eg. ria / fjord
eustatic = sea levels increase
isostatic = land levels decrease

32
Q

eustatic

A

change in sea level

33
Q

isostatic

A

change in land level

34
Q

transgression

A

eustatic sea levels increase, global, ice caps melt

35
Q

regression

A

isostatic rise in land level, emergent landform, eg Scotland

36
Q

ria

A

submerged river valley
deep in centre, shallow in cross section

37
Q

fjord

A

submerged glacial valley, 1000m deep, cliffs on sides,

38
Q

shingle beach

A

shingle = typically 2-200mm
sediment accumulates deposited by rivers, melt water streams, low energy waves.
end of last glacial period = sea levels were high and pushed sediment onshore

39
Q

raised beach

A

former shore platform, present beach

40
Q

tombolo

A

spit connects to mainland

41
Q

spit

A

prevailing winds blow at angle to coastline, creating lsd,extending the beach

42
Q

offshore bar

A

sediment eroded by deconstructive waves and carried seaward by backwash

43
Q

geo

A

long narrow cleft in cliff face formed by erosion at fault in rock

44
Q

blowhole

A

fault in cliff = erosion, sea cave pushed backwards and upwards due to weathering on top of cliff.

Geography Y12 (25 decks)

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