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Flashcards in Coasts Deck (56)
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1
Q

What is endogenetic energy?

A

Driven by geothermal energy from the earths interior

2
Q

What is exogenetic energy

A

Driven by solar energy which heats the surface creates wind waves and drives the hydrological cycle

3
Q

Examples of inputs

A
Waves
Sunshine
Tides
Currents
Offshore sediment
River sediment 
Estuary and land sediment
4
Q

Examples of processes

A
Erosion
Deposition
Sedimentation
Weathering
Mass movements
Transportation
5
Q

Examples of outputs

A
Silt and clay
Sand
Organic matter
Tides
Dredged sediment
Noise and heat
6
Q

Examples of stores

A
Saltmarshes
Mudflats
Sand banks
Sand, shingle and gravel beaches
Spits
7
Q

What physical factors influence the coastal landscape

A
Winds
Waves
Tides
Geology
Ocean current circulation
8
Q

What is a landform

A

A physical feature on the earths surface

9
Q

What is erosion

A

The wearing away of material by the action of the weather, ice or wind

10
Q

What is weathering

A

The disintegration of rocks by the action of the weather, plants, animals and chemical action

11
Q

What are marine processes

A

The action of the sea on coastal landforms

12
Q

What are sub aerial processes

A

Processes active on the face and top of cliffs

13
Q

What is mass movement

A

Movement of material downslope as a result of gravity

14
Q

What features may develop as a result of erosion

A
Caves
Arches
Stacks
Stumps
Wave cut platforms
15
Q

What landforms develop from depositional processes

A

Spits
Bars
Tombolos

16
Q

What factors combine to generate powerful waves

A

Strength of wind
Length of time it blows
Fetch

17
Q

What is fetch

A

The distance over which the wind has been blowing

18
Q

What is wavelength

A

Distance between crests

19
Q

What is frequency

A

Time between wave

20
Q

What is swash

A

Wave moves up the beach

21
Q

What is backwash

A

Wave moves back into the ocean

22
Q

what factors affect waves in the ocean

A

low pressure systems, fetch, size of swell window, sea floor gradient

23
Q

what is wave period

A

time for 1 wave to travel 1 wavelength

24
Q

what is the dominant wind

A

perpendicular to the coast - usually storm winds

25
Q

what is the prevailing wind

A

the most common direction

26
Q

beach store outputs

A

dredging and mining, wind and storm overwash, longshore drift, offshore transport

27
Q

beach store inputs

A

onshore transport, longshore drift, river sediment, cliff and sand dune erosion

28
Q

Constructive waves

A

Low in height
Long wavelength
Strong swash
Weak backwash

29
Q

Destructive waves

A

Greater height
Short wavelengths
Weak swash
Strong backwash

30
Q

What is freeze thaw

A

Water enters cracks/joints and expands by nearly 10 per cent when it freezes. In confined spaces this exerts pressure on the rock causing it to split or pieces to break off

31
Q

Pressure release

A

When overlying rocks are removed by weathering and erosion, the underlying rock expands and fractures parallel to the surface. This is significant in the exposure of sub-surface rocks as granite and is also known as dilatation. The parallel fractures are sometimes called pseudo-bedding planes.

32
Q

Thermal expansion

A

Rocks expand when heated and contract when cooled. If they are subjected it frequent cycles of temperature change then the outer layers may crack and flake off. This is also known as insolation weathering, although experiments have cast doubts on its effectiveness unless water is present

33
Q

Salt crystallisation

A

Solution of salt can seep into the pore spaces in porous rocks. Here the salts precipitate, forming crystals. The growth of these crystals create stress in the rock causing it to disintegrate.

34
Q

Oxidation

A

Some minerals in rocks react with oxygen, either in the air on in water. Iron is especially susceptible to this process. It becomes soluble under extremely acidic conditions and the original structure is destroyed. It often attacks the iron rich cements that bind the sand grains together

35
Q

Carbonation

A

Rainwater combines with dissolved co2 from the atmosphere to produce a weak carbonic acid. This reacts with calcium carbonate in rocks such as limestone to produce calcium bicarbonate, which is soluble.

36
Q

How does wind affect the coastline?

A

Wave energy is generators by the frictional drag of winds moving across the surface.
The higher the wind speed and the longer the fetch, the larger the waves and the more energy they possess.

37
Q

What is a sediment cell?

A

Stretch of coastline and it’s associated nearshore area within which the movement of coarse sediment, sand and shingle is largely contained

38
Q

Tree roots

A

Grow into cracks and joints and exert pressure. When trees topple their roots can also exert leverage in rock and soil, bringing them to the surface subject to more weathering

39
Q

Abrasion

A

Waves armed with rock particles scour the coastline, rock rubbing against rock

40
Q

Attrition

A

Rock particles collide with each other and progressively become worn away eventually producing sand

41
Q

Hydraulic action

A

Waves break against the cliff face and air and water trapped in cracks becomes compressed. As the wave recedes the pressure is released, the air and water expands and the crack is widened

42
Q

Solution

A

Dissolving of minerals e.g. Magnesium carbonate

43
Q

Suspension

A

Small particles of sand,silt and clay can be carried by currents

44
Q

Saltation

A

Series of irregular movements of material which is too heavy to be carried in suspension

45
Q

Traction

A

The largest particles in the load may be pushed along sea floor

46
Q

Horizontally bedded strata

A

Undercutting by wave action leads to rockfall

The cliff retreats inland

47
Q

Seaward dipping strata

A

Undercutting by wave action removes basal support

Rock layers loosened by weathering slide into sea along bedding planes

48
Q

Landward dipping strata

A

Rocks loosened by wave action are difficult to dislodge

49
Q

Wave refraction

A

When waves approach an irregularly shaped coastline, wave refraction takes place. As each wave nears the coastline it is slowed by friction in the shallower water. At the same time the part of the wave crest in the deeper water approaching the bay moves faster as it is not being slowed by friction. Therefore the waves bend and refract around the headland

50
Q

Sand beaches

A

Gentle gradient because small particle size means it becomes compact when wet allowing little percolation so material is carried down the beach

51
Q

Shingle beaches

A

Steep.

Little backwash occurs due to rapid percolation because if larger air spaces

52
Q

Spits

A

Formed by longshore drift occurring in one dominant direction. The end of the spit often becomes received as a result of wave refraction

53
Q

Onshore bars

A

When a spit continues to grow until it joins on to the land on the other side

54
Q

Tombolos

A

Beaches that connect mainland to an offshore island

55
Q

Salt marshes

A

Vegetated areas of deposited silt and clay.

Salt tolerant species such a sell grass help trap sediment gradually increasing height of marsh.

56
Q

Climate change decrease

A

Decrease in global temperatures leads to more precipitation being in the form of snow.
Eventually the snow turns into ice and so water is stored on land in solid form rather than in the sea as liquid