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Geography > Coasts - Unit 1 > Flashcards

Coasts - Unit 1 Flashcards

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1
Q

features of constructive waves

A
  • strong swash, weaker backwash
  • deposition greater (beach gain)
  • wave frequency = 6-8 per minute
  • short fetch
    wave period = 8-10 per second
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2
Q

features of destructive waves

A
  • weak swash, stronger backwash
  • erosion greater (beach loss)
  • wave frequency = 10-12 per minute
  • long fetch
  • wave period = 5-6 seconds
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3
Q

what is a closed system?

A

There is an input and output of energy but the amount of matter remains constant

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4
Q

what is an open system?

A

energy and matter can be inputted through and out of the system

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5
Q

input definition + example

A
  • energy and/or matter entering a system
  • precipitation, wind
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6
Q

output defnition + example

A

-energy and/or matter leaving a system
- ocean currents, evaporation, sediment transfer

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7
Q

store/component + example

A
  • the individual elements or parts of a system
  • a system in which energy can be transferred
  • beach, sand dunes
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8
Q

flow/transfer + example

A
  • movement between stores/components in a system
  • longshore drift, mass movement processes
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9
Q

boundary

A

-the edge of a particular system

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10
Q

energy

A

-power or driving force

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11
Q

what is dynamic equilibrium?

A

-balance within system, inputs and outputs are equal and stores remain the same
- when this system is disrupted it creates either positive or negative feedback

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12
Q

what is negative feedback?

A

the system acts to reverse the change returning it ti dynamic equilibrium

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13
Q

what is positive feedback?

A

the system acts to accelerate the change causing a snowball effect

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14
Q

What is wind?

A

the movement from higher to lower pressure areas

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15
Q

3 factors that affect the strength of waves?

A
  • strength of wind
  • duration of wind
  • fetch
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16
Q

how are waves formed?

A
  1. as air moves across the water, frictional drag disturbs the surface forming ripples or waves
  2. there is an orbital motion of water particles
  3. closer to shore the crest of the wave rises and gets steeper
  4. the circular motion turns to an elliptical motion in shallower water
  5. there is increasing friction on the bottom of the wave
  6. the wave length and velocity both decrease and the wave height increases causing water to back up from behind rand rise until eventually breaks
  7. this creates the swash and then backwash of the wave.
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17
Q

what are swell waves?

A

waves in open open water, characterised by long wavelengths and reduced height. They can reach up to 15m high and travel long distances

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18
Q

what are storm waves?

A

waves generated by local winds which travel only short distances. (waves nearer the coast)

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19
Q

what is wave refraction?

A

the change of direction of a wave as a result of travelling at different speeds at different speeds at different points along the wave front.

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20
Q

how does wave refraction work?

A
  • wave refraction causes energy to be concentrated on the headlands and dissipated in the bays.
  • waves slow down at the headland but stay the same velocity at the sides causing it to curve causing erosion round edges
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21
Q

how is wave refraction negative feedback?

A

the wave refraction erodes the headland and then longshore current replenishes it

22
Q

what are tides?

A

tides are the periodic rise and fall in the level of the sea and are caused by the gravitation pull of the sun and moon.
(moon is greater influence as closer)

23
Q

tidal range definition

A

the relative difference in height between high and low tide

24
Q

how do tides work?

A

the moon pulls the water towards it creating a bulge of high tide and low tide on each side which changes as the earth spins.

25
Q

spring tide definition

A

the highest monthly tidal range, when the moon, sun and earth are in a straight line that the tide raising force is to strongest.

26
Q

neap tide definition

A

twice a month, the moon and sun are positioned 90 degrees (perpendicular) too each other in relation to earth, this creates the lowest monthly tidal range.

27
Q

what are longshore currents?

A

occurs as most waves don’t hit the coast head on but at an angle to the shore, this generates a current running parallel to the shore
(therefore moves sediment parallel to the shore = drift align coastline)

28
Q

what are rip currents?
how do they develop?

A

strong currents moving along the shore
- they develop when seawater is piled up along the coastline by incoming waves.

29
Q

what is upwelling?

A

the movement of cold water from deep in the ocean toward the surface
- when more dense cold water replaces the warmer surface water and creates ocean currents.

30
Q

elements of a HIGH energy coastline?

A
  • wind and waves: strong, steady prevailing winds creating high energy waves
  • dominant coastal processes: erosion greater than deposition (hydraulic action and abrasion)
    -landforms: headlands, cliffs and wave-cut platform
31
Q

elements of a LOW energy coastline?

A
  • wind and waves: low wave energy, coast is sheltered from strong waves
  • dominant coastal processes: deposition
  • typical landforms: beaches and spits
32
Q

what is sediment?

A

only naturally occurring material that has been broken down by the processes of erosion and weathering and has been transported and subsequently deposited by the action of ice, wind and water

33
Q

what are sediment cells?

A

areas along the coastline where the movement of material is contained between two headlands or peninsulas. the shape of the coastline directs the movement of sediment.

THEY ARE CLOSED SYSTEM

34
Q

why are sediment cells closed systems

A

because sediment is not added or taken from the cell
- not entirely true, inputs could be increased by rockfall or increased output by harsh wind and weather conditions pushing it out to see.

35
Q

what are sediment budgets

A

the balance between changes in volume of sediment held within the system and the volume of sediment entering or level the system

36
Q

what’s a positive budget

A

when there are more inputs than outputs in a system

37
Q

what’s a negative budget

A

when outputs are higher than inputs

38
Q

what is physical weathering and what are the examples

A

involves the breakup of rocks without any chemical changes taking place.

  • freeze thaw weathering
  • salt crystallisation ( when salt water evaporates, it leaves salt crystals behind that grow overtime exerting stresses in rock which causes it to break)
  • wetting and drying (frequent cycle of wetting and drying cause rocks rich in clay, such as shale, to expand when they get wet and contract as they dry causing them to crack and break up)
39
Q

what is biological weathering and what are the examples

A

the breakdown of rocks by organic activity

  • plants (plants roots grow into small cracks in the cliff face, these cracks widen as the roots grow which breaks up the rock)
  • water (water running through decaying vegetation makes it acidic which leads to increases chemical weathering)
  • birds (animals dig burrows into cliffs)
  • marine organisms (burrowing into rocks or secreteing acid)
40
Q

what is chemical weathering and the examples

A

involves a chemical reaction where slats may be dissolved or a clay like deposit may result when easily eroded

  • carbonation (rainwater absorbs carbon dioxide from the air to form a weak carbonic acid, this reacts with carbonate in rocks, such as limestone and chalk to form calcium bicarbonate which is easily dissolved. the roller the temperature of the rainwater the more carbon dioxide is absorbed therefore carbonation is more effective in winter)
  • oxidation (the reaction of rock minerals with oxygen like iron to form a red powder leaving rocks more vulnerable to weathering)
  • solution (the dissolving of rock minerals such as halite)
41
Q

why does deposition occur?

A

deposition takes place when the velocity of the water falls below the critical value for a particular size of a particle and can no longer be transported, e.g. beaches, spits, bars

42
Q

what is lithology

A

includes resistance, permabilility, physical make up and chemical composition

43
Q

what are the four factors that affect lithology?

A
  1. RESISTANCE - how well a rock can withstand erosion, granite = most resistance, clay = lest resistance
  2. PERMEBILITY- wether a rock allows water to pass through
  3. PHYSICAL MAKE UP OF ROCKS - wether the rocks have joints (vertical) and bedding planes (horizontal)
  4. CHEMICAL COMPOSITION - wether the chemistry of a rock makes it vulnerable to chemical decomposition
44
Q

what is igneous rock?

A

when rocks are pushed deep into the earth they melt and form molten rock which takes the form of magma or lava, when these cool and condense from liquid to solid it creates igneous rock. lava cools quickly and as this happens igneous rocks also cool and have a small amount of time to grow crystals

EXAMPLE = GRANITE

45
Q

what is sedimentary rock?

A

sediment from the earths surface are collected at the bottom of lakes and oceans, overtime these are squashed and compacted together to become sedimentary rock such as sandstone or limestone.
sedimentary rock is laid down in layers and can contain fossils from animals and plants that become trapped in sediment before it becomes a rock.
made up of rounded grains (pores)

EXAMPLE = LIMESTONE

46
Q

what is metamorphic rock?

A

rocks that have changed overtime, when rocks are pushed deep into the earth, grains and minerals can be become stretched or squashed and slightly melted = METAPHORPHISM
recrystallisation of sedimentary and igneous rocks through heat and pressure

EXAMPLE = SLATE

47
Q

what are four key elements for a slat marsh to form

A
  • a relativity stable area of sediment covered by the tide for. short time
  • a supply of suitable sediment available
  • low water velocities for some of the sediment to be deposited
  • a supply of seeds to establish vegetation cover
48
Q

what’s a concordant coastline

A

where the rock bands run parallel to the surface to the coastline

49
Q

what’s a discordant coastline

A

where the rock bands run at right angles to the coastline

50
Q

what inputs are required for dunes to form

A
  1. large quantity of sand
  2. large tidal range
  3. dominant onshore winds

Geography (1 decks)

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