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GeoP - Coasts > Key Stuff > Flashcards

Key Stuff Flashcards

1
Q

formation of wave

A
  • winds move across surface of water, frictional drag (resistance to wind by water)
  • creates small ripples and waves
  • leads to circular orbital motion of water particles in ocean
  • as seabed shallower, orbit of water particles becomes more elliptical, leading to more horizontal movement
  • increased friction as waves approach the rough seabed, base of wave slowed down
  • as base slows, top fo wave continues, and breaks
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2
Q

size/energy of a wave

A
  • strength of wind
  • duration of wind (energy builds up)
  • size of the fetch (longer it is, more powerful wave, time to build up)
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3
Q

constructive waves

A
  • formed by weather systems that operate in open ocean
  • long wavelength
  • 6-9 per min
  • low waves, surge up beach
  • strong swash, weak backwash
  • gently sloped beaches
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4
Q

destructive waves

A
  • localised storm events with stronger winds operating closer to coast
  • short wavelength
  • 11-16 per min
  • high waves, plunge onto beach
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5
Q

high energy coastline

A
  • more powerful waves, occur in areas where large fetch
  • rocky headlands and landforms, frequent destructive waves
  • often eroding as rate of erosion exceeds rate of deposition
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6
Q

low energy coastline

A
  • less powerful waves, occur in sheltered area
  • constructive waves prevail, leads to sandy areas
  • depositional landforms, as deposition > erosion
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7
Q

wave refraction

A
  • @ headland and uneven coastlines
  • wave energy focused on headlands, creates erosive features in these areas
  • energy dissipated in bays, so forms depositional features (associated w low energy) such as beaches
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8
Q

Marine Action

A

hydraulic action
- air forced into cracks, joints and faults in rock when wave crashes onto rockface
- pressure from air causes cracks to force apart and widen when wave retreats and air expands
- over time causes rocks to fracture and weaken, and then break apart
corrasion/abrasion
- when rocks/other materials carried by sea picked up by strong waves and thrown at coastline = more material broken off, carried away by the sea
- size/shape/weight of sediment picked up, asw as wave speed, affects erosive power
solution
- water dissolving in rocks and materials into solutions. acidic seawater cases alkaline rock e.g limestone to be eroded
attrition
- wave action = rocks and pebbles hit each other, wearing down, = rounder and smaller.

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9
Q

sub aerial process

A
  • land-based process, occurs above the waterline
  • mass movement, weathering
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10
Q

traction

A

large, heavy sediment rolls along sea bed, pushed by currents

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11
Q

saltation

A

smaller sediment bounces along sea bed, pushed by currents, sediment too heavy to be fully picked up by flow of water

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12
Q

suspension

A
  • small sediment carried within flow of water
  • greater velocity water able to suspend larger, heavier pieces
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13
Q

solution

A

dissolved material carried within water in chemical form potentially

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14
Q

flocculation

A

clay particles clump together due to chemical attraction and then sink due to high density

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15
Q

sediment sources

A

rivers
- majority sediment in coastal zones from input from rivers, esp high rainfall environments where lots of erosion
- e.g gulf Mexico, sediment flowing from river delta
- deposited in estuaries, brackish areas where rivers flow into sea. important wildlife habitat.
- sediment transported throughout coastal system by waves, tides, currents
cliff erosion
- unconsolidated cliffs eroded easily.
- some areas cliffs can retreat up to 10m yearly, providing lot of sediment
- most erosion in winter due to storm ssn
wind
- coastal energy source, causes sand to be blown along/up beach
- sediment transport by wind maybe where sand dunes or in glacial/desert env
glaciers
- in some systems (Antarctica, Alaska etc) glaciers flow directly into ocean depositing sediment that was stored in ice
- occurs when glaciers calve, a process where3 ice breaks off glacier
offshore
- sediment transferred to coastal zone when waves, tides, currents erode offshore sediment sinks (offshore bars)
- sediment transported up beach, helping build it up
- storm surges/tsumani waves also transfer sediment
LSD
- waves hit beach @ angle (prevailing wind)
- sediment up beach as swash, down beach as backwash
- moves along beach over time
human action
- hard/soft engineering starts (beach nourishment)

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16
Q

sediment cells

A
  • bordered by prominent headlands
  • movement of sediment contained within headlands, flows of sediment act in dynamic equilibrium
17
Q

steep cliffs

A

most common where rock is strong and resistant to erosion
- sedimentary rocks that have vertical strata v. resistant to erosion
- absence of beach, long fetch + high energy waves promote steep cliff development

18
Q

gentle cliffs

A
  • areas with weaker rocks, less resistant to erosion, prone to slumping
  • large beach also reduces wave energy, prevents steep cliffs by reducing erosion
19
Q

rate of retreat

A
  • depends on relative importance of marine factors (fetch, beach, wave energy), and terrestrial factors (subaerial processes, geology, rock strength)
  • most likely unconsolidated rock and sands will retreat
20
Q

spits

A
  • formed when LSD causes beach to extend to sea, from change in direction of coastline
  • makes slt harsh behind it due to sheltered saline environment, slower water speed
  • change in wind/wave direction can cause end of spit to curve (recurved)
  • received may be abandoned, new spit will form on recurved end, forming many spits (compound spit)
21
Q

offshore bar

A
  • offshore area where send deposited as waves don’t have enough energy to carry sediment to shore
  • formed when wave breaks early
  • or destructive waves backwash removing sediment from beach
22
Q

tombolo

A

spit that connects mainland to offshore island

23
Q

barrier beach

A
  • when beach or spit extends across bay to join 2 headlands
  • traps water behind leading to formation of brackish lagoon
24
Q

barrier beach (bar)

A

when beach/spit extends across bay to join 2 headlands
- traps water behind to form lagoon

25
Q

salt marshes

A

in sheltered bays or behind spits salt and minerals build up
- veg establishes, further stabilising

26
Q

sand dune

A
  • wind blows fine sediment to back of beach
  • large tidal range allows sand to dry and be moved to back
  • vegetation succession allows dune to form, with resistant plants roots helping bind everything together
27
Q

mangroves

A

trees adapted to grow in saline, low oxygen conditions
- develop in coastal swamps
- can stabilise shorelines w/ roots and protect areas from erosion

28
Q

isostatic change

A
  • when land rises or falls relative to the sea, and is localised change
  • scotland and NW england rising abt 1.5mm a year, but land in SE subsiding 1mm a year
29
Q

eustatic change

A
  • affects sea level across whole planet
  • may be due to thermal expansion/contraction in glacial processes.
  • expansion is water expanding as warmer, so volume increases = rising SL
  • global warming so volume increasing
30
Q

tidal sedimentation in estuaries

A
  • estuary is point where river meets ocean
  • deposition occurs as change in velocity
  • when flow from river meets incoming tides from sea, water ceases, cant carry sediment
  • deposits, leads to build u of mud, until above water (dep also from flocculation)
30
Q

emergent coastal landforms

A
  • where land has been raised in relation to coastline, landforms e.g arches stacks stumps preserved
  • raised beaches common
30
Q

submergent coastal landforms

A
  • when SL rise/coastline sinks in relation to sea
    rias
  • when rising sea levels flood narrow winding inlets and river valleys
  • deeper at mouth, water depth increases further inland
    fjords
  • when rising SL flood deep glacial valleys to make natural inlet/harbour
  • found worldwide, lost in NZ
  • deeper in middle than at mouth

GeoP - Coasts (12 decks)

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