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Geography A Level > Coasts > Flashcards

Flashcards in Coasts Deck (56):
1

What is endogenetic energy?

Driven by geothermal energy from the earths interior

2

What is exogenetic energy

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

3

Examples of inputs

Waves
Sunshine
Tides
Currents
Offshore sediment
River sediment
Estuary and land sediment

4

Examples of processes

Erosion
Deposition
Sedimentation
Weathering
Mass movements
Transportation

5

Examples of outputs

Silt and clay
Sand
Organic matter
Tides
Dredged sediment
Noise and heat

6

Examples of stores

Saltmarshes
Mudflats
Sand banks
Sand, shingle and gravel beaches
Spits

7

What physical factors influence the coastal landscape

Winds
Waves
Tides
Geology
Ocean current circulation

8

What is a landform

A physical feature on the earths surface

9

What is erosion

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

10

What is weathering

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

11

What are marine processes

The action of the sea on coastal landforms

12

What are sub aerial processes

Processes active on the face and top of cliffs

13

What is mass movement

Movement of material downslope as a result of gravity

14

What features may develop as a result of erosion

Caves
Arches
Stacks
Stumps
Wave cut platforms

15

What landforms develop from depositional processes

Spits
Bars
Tombolos

16

What factors combine to generate powerful waves

Strength of wind
Length of time it blows
Fetch

17

What is fetch

The distance over which the wind has been blowing

18

What is wavelength

Distance between crests

19

What is frequency

Time between wave

20

What is swash

Wave moves up the beach

21

What is backwash

Wave moves back into the ocean

22

what factors affect waves in the ocean

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

23

what is wave period

time for 1 wave to travel 1 wavelength

24

what is the dominant wind

perpendicular to the coast - usually storm winds

25

what is the prevailing wind

the most common direction

26

beach store outputs

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

27

beach store inputs

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

28

Constructive waves

Low in height
Long wavelength
Strong swash
Weak backwash

29

Destructive waves

Greater height
Short wavelengths
Weak swash
Strong backwash

30

What is freeze thaw

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

Pressure release

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

Thermal expansion

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

Salt crystallisation

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

Oxidation

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

Carbonation

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

How does wind affect the coastline?

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

What is a sediment cell?

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

38

Tree roots

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

Abrasion

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

40

Attrition

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

41

Hydraulic action

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

Solution

Dissolving of minerals e.g. Magnesium carbonate

43

Suspension

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

44

Saltation

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

45

Traction

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

46

Horizontally bedded strata

Undercutting by wave action leads to rockfall
The cliff retreats inland

47

Seaward dipping strata

Undercutting by wave action removes basal support
Rock layers loosened by weathering slide into sea along bedding planes

48

Landward dipping strata

Rocks loosened by wave action are difficult to dislodge

49

Wave refraction

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

Sand beaches

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

51

Shingle beaches

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

52

Spits

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

53

Onshore bars

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

54

Tombolos

Beaches that connect mainland to an offshore island

55

Salt marshes

Vegetated areas of deposited silt and clay.
Salt tolerant species such a sell grass help trap sediment gradually increasing height of marsh.

56

Climate change decrease

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