Coasts (Topic 1)

Question 1

Why can coastal landscapes be viewed as open systems?

Answer 1

• Energy and matter can be transferred from neighbouring systems as an input + transferred to neighbouring systems as an output

Question 2

What are the components of an open system? (4)

Answer 2

1. Inputs
2. Outputs
3. Processes
4. Stores

Question 3

What is a state of equilibrium in a system?

Answer 3

• When inputs and outputs are equal

Question 4

What is dynamic equilibrium in a coastal system?

Answer 4

• When the Eq is disturbed, system goes under self-regulation and changes its form in order to restore the Eq - system produces its own response to the disturbance

Question 5

What type of feedback is dynamic Eq an example of?

Answer 5

• Negative - an automatic response that restores Eq

Question 6

What is a sediment cell?

Answer 6

• A stretch of coastline and its associated nearshore area within which the movement of coarse sediment, sand and shingle is largely self-contained

Question 7

How many large sediment cells are there around England and Wales?

Answer 7

• 11

Question 8

What are the boundaries of sediment cells determined by?

Answer 8

• Topography and shape of coastline

Question 9

Why are sediment cells generally regarded as a closed system?

Answer 9

• Suggests that no sediment is transferred from one cell to another - held within the headlands (barriers)

Question 10

Why, in reality, is it unlikely that sediment cells are completely closed? (2)

Answer 10

1. Variations in wind direction and presence of tidal currents = inevitable that some sediment is transferred between neighbouring cells
2. Many sub-cells of a smaller scale exist within the major cells

Question 11

How does wind influence coastal systems?

Answer 11

1. Winds are the source of energy for waves
2. Wind direction can influence the impact of waves (oblique waves = LSD)
3. Aeolian processes can erode or transport and deposit sediment

Question 12

Describe the anatomy of a wave?

Answer 12

1. Crest - highest surface part of the wave
2. Trough - lowest part
3. Wave height - vertical distance between trough and crest
4. Wavelength - horizontal distance between 2 adjacent crests/troughs

Question 13

What is the difference between swell and storm waves?

Answer 13

Swell waves - longer wavelength, wave period of ~20s

Storm waves - short wavelength, greater height and shorter wave period

Question 14

Describe the process of a breaking wave?

Answer 14

1. Wave move into shallow water
2. Wave slow down (friction)
3. Wavelength decreases = successive waves bunch up
4. Deepest part of wave slows down more than the top
5. Wave steepens - crest advances ahead of base
6. When water depth is less than 1.3x wave height, wave topples over and breaks against shore

Question 15

Describe a constructive wave?

Answer 15

• Low in height, long wavelength, low frequency
• Break by spilling forwards, strong swash travels a long way up gently sloping beaches
• Long wavelength = backwash returns to sea before next wave breaks = next swash movement is uninterrupted and thus retains its energy

Question 16

Describe a destructive wave?

Answer 16

• Greater height, shorter wavelengths and a higher frequency
• Break by plunging downwards = little forward transfer of energy to move water up the steeply sloping beach as friction slows swash, so wave does not travel far
• Short wavelength = swash of next wave often slowed by the frictional effects of meeting the returning backwash of the previous wave
• Swash energy is less than backwash energy

Question 17

What produces tides?

Answer 17

• The gravitational pull of the moon, and to a lesser extent, the sun
• The moon pulls water towards it, creating a high tide

Question 18

What is a spring tide AND what happens during it?

Answer 18

• When the moon, sun and earth = aligned
  = Higher high tides and lower low tides

Question 19

What is a neap tide AND what happens during?

Answer 19

• Moon and sun at right angles to each other
  = Lower high tides and higher low tides

Question 20

How does tidal range influence coastal landscapes?

Answer 20

• In enclosed areas (Mediterranean) - tidal range are low and so wave action is restricted to a narrow area of land
• In areas where coast is funnelled (Servern Estuary) - tidal ranges can be as high as 14m

Question 21

What is meant by lithology?

Answer 21

• Chemical and physical composition of rocks

Question 22

How are coastal systems influenced by lithology?

Answer 22

• Differences in rock lithology = varying levels of susceptibility to erosion, weathering and mass movements = formation of different coastal formations

Question 23

What is meant by structure in regards to geology?

Answer 23

• Structure concerns the properties of individual rock types such as jointing, bedding and faulting
• Also includes the permeability of rocks

Question 24

What is meant by porous rocks?

Answer 24

• Rocks which contain pores of air spaces between mineral particles, where water is stored

Question 25

What is meant by permeable?

Answer 25

- A type of rock that is penetrated by water, either through mineral pores or along joints, faults and fissures

Question 26

How does structure influence coastal landscapes?

Answer 26

1. Important influence on the planform of coasts at regional scale e.g. rock outcrops that run parallel to coast = straight coastlines (concordant) - rocks that lie at right angles to the coast create discordant coastlines - more resistant rocks for headlands, weaker rocks for bays 2. Influence on cliff profiles - horizontally bedded/landward dipping = steep vertical cliff profiles - strata/seaward dipping = profiles tend to follow the angle of bedding plane

Question 27

How are ocean currents generated?

Answer 27

- Generated by the Coriolis effect and convection and are set in motion by the movement of winds across the water surface

Question 28

How do ocean currents influence coastal landscapes?

Answer 28

- Strength of the current = limited impact in terms of geomorphic processes (driven by offshore winds = less effect on coastal landscapes) but the transfer of heat energy = significant- directly affects air temperature, therefore sub-aerial processes

Question 29

What is terrestrial sediment?

Answer 29

- Sediment from land

Question 30

What are the main sources of sediment input?

Answer 30

- Rivers - some locations, as much as 90% of coastal sediment comes from rivers

Question 31

What is the origin of terrestrial sediment?

Answer 31

- Erosion of inland areas by water, wind and ice as well as sub-aerial processes (weathering and mass movement)

Question 32

What are the other sources of terrestrial sediment

Answer 32

1. Wave erosion 2. Cliff erosion - increased by rising sea levels and amplified by storm surge events - erosion of weak cliffs in high energy wave environments contributes as much as 70% of the overall material supplied to beaches 3. LSD

Question 33

What type of waves bring sediment to the shore from offshore locations and deposit it

Answer 33

- Constructive waves

Question 34

What also brings sediment to the shore from offshore locations?

Answer 34

1. tides 2. currents 3. wind - blows sediment from other locations (exposed sand bars, dunes and beaches along the coast) - material is generally fine sand

Question 35

What is a way in which sediment equilibrium can be maintained?

Answer 35

- beach nourishment

Question 36

How can beach nourishment occur?

Answer 36

1. Sediment brought in by a lorry and dumped on the beach before spread by bulldozers 2. Sand and water can be pumped onshore by pipeline from offshore sources

Question 37

What is weathering?

Answer 37

- the use of energy to produce physically or chemical altered materials from surface or near surface rocks

Question 38

The breakdown of rock is largely achieved by which weathering process?

Answer 38

- Physical weathering processes

Question 39

What doesn't take place during physical weathering?

Answer 39

- Chemical alterations

Question 40

How does physical weathering allow for more weathering to take place?

Answer 40

- Increase the exposed surface area of the rock

Question 41

Why are some physical weathering processes ineffective?

Answer 41

- In many coastal landscapes, the presence of sea results in moderation of temperature, so air temperature may drop below 0, reducing the extent of fluccuations

Question 42

What are the typical physical weathering processes of coastal environment?

Answer 42

1. Freeze-thaw 2. Pressure release 3. Thermal expansion 4. Salt crystalisation

Question 43

How does freeze-thaw work?

Answer 43

1. water enters cracks or joints 2. expands by nearly 10% when freezes 3. exerts pressure on rock - causing to split into pieces

Question 44

How does pressure release work?

Answer 44

1. overlying rocks are removed by weathering/erosion 2. underlying rocks expand and fracture parallel to the surface 3. significant in exposure of sub-surface rocks

Question 45

How does thermal expansion work?

Answer 45

1. rocks expand when heated/ contract when cooled 2. if subject to frequent cycles of temp change, outer layers may crack and flake off

Question 46

How does salt crystallisation work?

Answer 46

1. Solutions of salt seep into pore spaces 2. Salt precipitates, forming crystals 3. The growth of these crystals creates stress in rock, causing it to disintegrate

Question 47

What is the result of chemical weathering?

Answer 47

- the decay of rocks

Question 48

What do chemical processes produce?

Answer 48

- Weak residues of different materials that may then be easily removed by erosion or transportation processes

Question 49

What causes most chemical reactions to increase?

Answer 49

- Increasing temperature

Question 50

Where do higher rates of chemical weathering take place?

Answer 50

- tropical regions

Question 51

Why is carbonation more effective at lower temperatures?

Answer 51

- As CO2 is more soluble in cold water rather than hot

Question 52

What are the processes of chemical weathering?

Answer 52

1. oxidation 2. carbonation 3. solution 4. hydrolysis 5. hydration

Question 53

What is oxidation?

Answer 53

- When some minerals in rocks react with oxygen, either in the air or water

Question 54

What is carbonation?

Answer 54

- When rainwater combines with dissolved CO2 from the atmosphere to produce a weak carbonic acid - This reacts with the CaCO3 in rocks to produce Calcium Bicarbonate

Question 55

What is solution?

Answer 55

- Any process by which a mineral dissolves in water

Question 56

What is hydrolysis?

Answer 56

- A chemical reaction between rock minerals and water

Question 57

What is hydration?

Answer 57

- When water molecules added to rock minerals create new minerals of a larger volume

Question 58

What type of processes may biological weathering consist of?

Answer 58

1. Physical actions (growth of plant roots) 2. Chemical processes (Chelation by organic acids)

Question 59

What are the processes of biological weathering?

Answer 59

1. Tree roots 2. Organic acids

Question 60

How does biological weathering by tree roots work?

Answer 60

1. Tree roots grow into cracks/joints in rocks and exert outward pressure 2. When trees topple, their roots can also exert leverage on rock and soil - this brings them to the surface and exposes them to further weathering

Question 61

What may have a similar effect to tree roots?

Answer 61

- Burrowing animals

Question 62

How does biological weathering by organic acids work?

Answer 62

1. Organic acids (produced during the decomposition of plant and animal litter) causes soil water to become more acidic and react with some minerals (chelation) 2. Blue-green algae produce a shiny film of iron and manganese oxides on rocks - this breaks down metallic irons in rocks 3. On shore platforms, molluscs may secrete acids which produce small surface hollows in the rock - rocks more susceptible to types of erosion

Question 63

When does mass movement occur?

Answer 63

- When the forces acting on slope material (gravity) exceed the force trying to keep material on the slope (friction)

Question 64

What are the main processes in mass movement?

Answer 64

1. Rock fall 2. Rock slides

Question 65

How does rock fall occur?

Answer 65

1. On cliffs of 40* or more, rocks may become detached from the slope by physical weathering processes 2. These fall to the foot of the cliff under gravity 3. Wave processes remove this material, or it may accumulate as. a relatively straight, lower angled screen slope

Question 66

What are the types of slides?

Answer 66

1. Linear - movement along a straight line slip plane, such as a fault or a bedding plane between layers of rocks 2. Rotational - movement taking place along a curved slip plane (also known as slumps)

Question 67

Why do slides occur?

Answer 67

- Undercutting by wave erosion at the base of cliff which removes support for the materials above

Question 68

What type of rocks are slumps common in?

Answer 68

- Weak rocks, such as clay, which also become heavier when wet, adding to the downward force

Question 69

What processes are breaking waves able to erode the coastline with?

Answer 69

1. Abrasion 2. Attrition 3. Hydraulic action 4. Pounding 5. Solution

Question 70

What is abrasion?

Answer 70

- When waves armed with rock particles scour the coastline - rock rubbing against rock

Question 71

What is attrition?

Answer 71

- When rock particles transported by wave action collide with each other and with coastal rocks and progressively become worn away

Question 72

What is hydraulic action?

Answer 72

- Waves break against a cliff face, and air and water trapped in racks and crevices becomes compressed - As the wave pressure is released - air and water suddenly expand and the crack is widened

Question 73

What is pounding?

Answer 73

- When the mass of the breaking wave exerts pressure on the rock causing it to weaken

Question 74

What is solution?

Answer 74

- Dissolving minerals like magnesium carbonate in coastal rock

Question 75

Why is solutions impact limited?

Answer 75

- pH of sea is around 7-8, meaning process is of limited significance, unless the water is locally polluted and acidic - Even then, only coastal rocks containing significant amounts of soluble minerals are affected by this

Question 76

What are the processes by which waves move material?

Answer 76

1. Traction 2. Saltation 3. Suspension 4. Solution 5. LSD

Question 77

What is traction?

Answer 77

- Where the largest particles are pushed along the sea floor by the force of flow

Question 78

What is saltation?

Answer 78

- The irregular movements of material that are too heavy to be carried continuously in suspension

Question 79

What is suspension?

Answer 79

- Small particles of sand, silt and clay carried by currents - explains the brown, muddy appearance of some sea water

Question 80

What is solution?

Answer 80

- Minerals dissolving into mass of moving water - remain in solution until evaporated and then precipitated out of solution

Question 81

What is long-shore drift?

Answer 81

- wave approach shore at angle due to dominant wind direction- swash carries particles diagonally up beach, backwash moves them back perpendicular to coastline (influenced by gravity)

Question 82

When does deposition tend to take place in coastal landscape systems?

Answer 82

1. where the rate of sediment accumulation exceeds the rate of removal 2. when waves slow down immediately after breaking 3. at the top of the swash, where for a brief moment, the water is no longer moving 4. during the backwash, when water percolates into the beach material 5. in low-energy environments, such as those sheltered from winds and waves (e.g. estuaries)

Question 83

What is the settling velocity?

Answer 83

- the velocity at which sediment particles are deposited

Question 84

What is the main source of a rivers sediment load?

Answer 84

- Erosion in the upper catchment

Question 85

How else is sediment derived into river channels?

Answer 85

1. Weathering 2. Mass movement

Question 86

What are the processes by which rivers carry out erosion?

Answer 86

1. abrasion (or corrasion) 2. attrition 3. hydraulic action 4. pounding 5. solution (or corrosion)

Question 87

What processes do rivers transport sediment by?

Answer 87

1. traction 2. saltation 3. suspension 4. solution

Question 88

Why do rivers deposit their load?

Answer 88

1. as rivers enter sea, noticeable reduction in velocity, as flowing water from channel enters the relatively static body of the sea 2. tides & currents may be moving in opposite direction to the river flow, providing a major resistance to its forward movement

Question 89

What does the meeting of salt and fresh water lead to?

Answer 89

- the flocculation of clay particles

Question 90

What is flocculation?

Answer 90

fine, light clay material clump together due to electrical charges between them in saline conditions- become heavier and sink to the sea bed

Question 91

What does deflation allow the wind to do?

Answer 91

- Pick up sand particles and move them by deflation

Question 92

Why is dry sand easier for the wind to pick up?

Answer 92

- moisture increases cohesion between particles, helping them stick together

Question 93

How is moving air able to transport minerals?

Answer 93

1. traction 2. saltation 3. suspension

Question 94

What usually causes wind speed to fall?

Answer 94

surface friction- e.g. inland from vegetation and surface irregularities (much greater than on open sea)

Question 95

How do cliffs form?

Answer 95

1. destructive waves & steeply sloping coastlines = undercutting, forms a wave-cut notch 2. continued undercutting = weaken support for rock strata above 3. rock strata eventually collapses, producing a steep profile and a cliff 4. regular removal of debris at foot of cliff (wave action) ensures that the cliff profile remains relatively steep & that the cliff retreats inland parallel to the coast

Question 96

What are the different types of bedded-strata AND what cliff profiles do them support?

Answer 96

1. landward-dipping strata- steep, near vertical profile- the slope profile is gradually lowered by weathering and mass movement 2. seaward-dipping strata- profile follows the angle of dip- undercutting by wave action removes support; rock layers loosen and slide into sea along bedding planes 3. horizontally-bedded strata- steep, near vertical profile; undercutting by wave action = rock fall; cliff retreats inland parallel to the coast

Question 97

How do shore platforms form?

Answer 97

1. undercutting continues; cliff becomes higher; at base, a gently sloping shore platform is cut into the rock 2. eventually the platform will be so wide that it produces shallow water and small waves 3. friction from the platform slows down approaching waves = break on the platform rather than the cliff = undercutting slows and eventually ceases (width of approx. 500m before this...)

Question 98

What weathering processes are also important in forming shore platforms?

Answer 98

1. solution 2. freeze-thaw 3. salt crystallisation

Question 99

How do marine organisms accelerate weathering when the platform is exposed at low tide? [3]

Answer 99

1. at night, algae release CO2 (photosynthesis not happening) 2. mixes with sea water = more acidic 3. results in higher rates of chemical weathering

Question 100

Why are these features worse developed if the tidal range is more than 4m? [2]

Answer 100

1. erosion is spread over a wider area of the platform 2. water is at its high & low tide positions for shorter time = platform tends to be more uniform and more steeply sloping

Question 101

What type of coastline is it if different rock outcrops lie perpendicular to the coastline?

Answer 101

- Discordant

Question 102

Why do bays and headlands form?

Answer 102

- weaker rocks are eroded more rapidly to form bays; more resistant rocks remain as headlands

Question 103

What determines the width of a bay?

Answer 103

the width of the band of weaker rock

Question 104

What determines the depth of a bay?

Answer 104

depend on the differential rates of erosion between the more resistant and weaker rocks

Question 105

What type of coastline is it if rock types lie parallel to the coastline?

Answer 105

- concordant

Question 106

What happens if the more resistant rock lies on the seaward side?

Answer 106

protects any weaker rocks inland from erosion- resultant coastline is relatively straight and even

Question 107

How can small bays or coves still be eroded in a concordant, resistant coastline?

Answer 107

at points of weakness, such as fault lines

Question 108

What is an example of a concordant and discordant coastline?

Answer 108

Isle of Purbeck, Dorset east-facing coast is discordant south-facing coast is concordant

Question 109

What is wave refraction?

Answer 109

the change of direction of wave fronts as they enter shallow water so that they approach parallel to the shoreline

Question 110

What causes wave refraction to take place?

Answer 110

when waves approach an irregularly shaped coastline

Question 111

What happens when waves approach a coastline with bays and headlands?

Answer 111

headlands: wave energy focussed on headland, erosion concentrated there bays: orthagonals diverge and energy is dissipated, leading to deposition

Question 112

What is a geo?

Answer 112

a narrow, steep-sided inlet

Question 113

How do geos form? [4 steps)

Answer 113

1. waves attack the coastline 2. lines of weakness in coastlines (i.e. joints and faults) are eroded more rapidly by wave action (i.e. hydraulic action and abrasion) weakening the rock strata 3. a tunnel-like cave is created 4. cave is enlarged by continuing erosion- leads to collapse of the roof of the cave

Question 114

What is an example of a geo?

Answer 114

Huntsman's Leap, Pembrokeshire 35m deep & eroded along a large joint in the carboniferous limestone

Question 115

How do blowholes form? [5 steps]

Answer 115

1. waves attack the coastline 2. lines of weakness in coastlines (i.e. joints and faults) are eroded more rapidly by wave action (i.e. hydraulic action and abrasion) weakening the rock strata 3. a tunnel-like cave is created 4. part of the roof of the cave collapse along master joint, which may form a vertical shaft that reaches the cliff top 5. during stormy conditions, larger waves may force spray out of blowholes as plumes of white, aerated water

Question 116

What may geos and blowholes also be associated with AND an example?

Answer 116

Mining shafts e.g. Trevone, Cornwall (25m deep blowhole)

Question 117

How do caves, arches, stacks and stumps form? [5 steps]

Answer 117

1. wave refraction = energy of wave focussed on side of a headland 2. points of weakness (i.e. joints or faults) exploited (hydraulic action & abrasion) = formation of a cave in location between high and low tide (where wave attack concentrated) 3. cave enlarges so that extends to other side of the headland/meets another cave in process = formation of arch 4. continued erosion widens arch & weakens support (aided by weathering processes)- arch collapses, leaving an isolated stack separate from the headland 5. further erosion at the base of the stack causes it to collapse further, leaving a flat, small portion of the original stack as a stump (may only be visible at low tide)

Question 118

What is an example of the sequence of cave, arch, stack and stump?

Answer 118

Old Harry Rocks, Isle of Purbeck

Question 119

What do beaches represent?

Answer 119

the accumulation of material deposited between the lowest tides and the highest storm waves

Question 120

What are the main source of beach material? [3]

Answer 120

1. cliff erosion (5%) 2. offshore (5%) 3. rivers (up to 90%)

Question 121

What type of beaches does sand produce?

Answer 121

entle gradient (usually less than 5*)- small particle size means that it becomes compact when wet, allowing little percolation during backwash = little energy lost to

Question 122

What is a salt marsh?

Answer 122

Vegetated areas of deposited silts and clays, regularly flooded by water - the UK has 45,500 ha of salt marsh.

Question 123

Explain the formation of a salt marsh (6)

Answer 123

1. Low-energy environment required - e.g. landward side of a spit. 2. Daily inundation (2x per day) - driven by tides -> salt tolerant plant species (i.e. eelgrass and spartina) trap sediment = increased height - sediment (10cm per year) from rivers and flocculation. 3. Marsh increases in height = shorter period of daily submergence & less saline conditions (reeds etc) // lower marsh = high salinity, turbid water, long submergence (species diversity = poor). 4. At high parts of marsh, low-energy, slack water present for 2-3 hours = high deposition rates. 5. Small, steep-sided channels, or creeks = drain marsh at low tide/routes for water to enter as tide rises -> between creeks = saltpans (trap water when tide falls).

Question 124

What physical factors affect changes in global temperature and the volume of water in oceans?

Answer 124

1. Variations in Earth's orbit around the sun 2. Variations in the tilt of the Earth's axis 3. Variations in the energy produced by the sun 4. Major Volcanic eruptions

Question 125

What is the milankovitch cycle?

Answer 125

- It describes the collective effects of hange in the Earth's movements on its climate over thousands of years

Question 126

What physical factors are part of the Milankovitch cycle? (3)

Answer 126

1. Variations in Earth's orbit around the Sun. 2. Variations in the tilt of the Earth's axis. 3. Variations in energy produced by the Sun

Question 127

What periods does the Milankovitch cycle drive? (2)

Answer 127

1. Glacial period 2. Inter-glacial period

Question 128

What is meant by eustatic?

Answer 128

A global change in sea level resulting from an actual fall or rise in the level of the sea. Glacial periods = eustatic sea level fall (more ice = less water). Interglacial periods = eustatic sea level rise (more ice melt = more water).

Question 129

What is meant by isostatic?

Answer 129

Local changes in sea level resulting from the land rising or falling relative to the sea.

Question 130

How does a decrease in global temperature impact sea levels? (2)

Answer 130

1. Leads to more snow = snow turns to ice = water stored in solid form rather than being returned to ocean store as liquid = eustatic sea level fall. 2. Lower temps = water molecules contract = increased density (and reduced volume)- est. that 1*C fall in mean global temp = sea level fall by approx. 2m.

Question 131

8-mark question structure (3 parts) - Emergent landforms

Answer 131

1. Past -Interglacial -Glacial 2. Present day interglacial 3. Future modifications -Warmer = eustatic sea level rise Stormier (waves = more erosive power) -Chemical weathering -Vant Hoff's Law (10*C increase = 2.5x faster chemical reactions) -Biological weathering (vegetation & marine organisms- e.g. limpets and whelks)

Question 132

What is an abandoned cliff?

Answer 132

Sea level used to be at base of cliff, but due to eustatic sea level fall, sea level is now below cliff, so marine processes not dominant.

Question 133

Describe the formation of an abandoned cliff (3)

Answer 133

1. Past -Interglacial: eustatic sea level rise = marine erosion is dominant process (hydraulic action & abrasion & pounding). -Glacial: eustatic sea level fall = sub-aerial processes dominant (i.e. physical/biological weathering). 2. Present -Eustatic sea level rise (but still 20m lower than when cliff formed) although some eustatic rise = marine erosion becoming more dominant- but not all areas. -Warmer temps = increased chemical weathering processes. 3. Future -Increased marine erosion (eustatic sea level rise). -Stormier conditions = waves more erosive force. -Increased chemical weathering (increasing temps). -Further altercations to cliffs.

Question 134

What is a raised beach?

Answer 134

Areas of former shore platforms that are left at a higher level than the present sea level. They are often found a distance inland from the present coastline.

Question 135

Describe the formation of a raised beach (3)

Answer 135

1. Past -Interglacial: 3*C warmer than today = eustatic sea level rise (+20m than today) = marine erosion dominant (hydraulic action, abrasion) at base of cliffs = undercutting & retreat (mass movement- rock fall) = formation of wave cut platform. -Glacial: eustatic sea level fall = marine erosion less dominant = sub-aerial processes (i.e. biological, physical- e.g. freeze thaw). 2. Present -Eustatic sea level rise (but still 20m lower than when cliff formed) although some eustatic rise = marine erosion becoming more dominant- but not all areas. -Warmer temps = increased chemical weathering processes. 3. Future -Increased marine erosion (eustatic sea level rise). -Stormier conditions = waves more erosive force. -Increased chemical weathering (increasing temps). -Further altercations to raised beaches.

Question 136

What is a marine terrace?

Answer 136

Much larger landscape features than raised beaches (which are smaller/more localised at base of relic cliffs). Terraces do not necessarily have cliffs above them.

Question 137

Describe the formation of a marine terrace

Answer 137

Formation essentially same as raised beaches- marine erosion during previous period of higher sea level.

Question 138

How does an increase in global temperature impact sea levels?

Answer 138

1. Higher temps = higher rates of melting of ice stored on land in ice sheets, ice caps and valley glaciers = global increase in volume of water in the ocean store (consequent rise in sea level). 2. Water molecules expand = increase in volume- e.g. 1*C rise in mean global temps = sea level rise of approx. 2m.

Question 139

What period does the Flandrian Transgression cover?

Answer 139

12,000 years ago (end of last glacial period) to present day.

Question 140

What has occurred in the Flandrian Transgression?

Answer 140

Temperatures & sea levels have risen to their present level.

Question 141

8-mark question structure (3) - Submerging landscapes

Answer 141

1. Past - glacial 2. Present - interglacial 3. Future - warming climate

Question 142

What is a ria?

Answer 142

A ria is a submerged river valley, formed as sea level rises.

Question 143

Describe the formation of a ria (3)

Answer 143

1. Past (glacial) -Eustatic sea level fall due to more water stored in ice = coastline further out to sea. 2. Present (inter-glacial) -Eustatic sea level rise (Flandrian Transgression) = floods plains/mouth of river inundated. -Valley sides remain exposed. 3. Future -Eustatic sea level rise = flooding/increased depth. -More erosive power of water. -More weathering occurs on valleys = create an even more gently sloping valley.

Question 144

What is a shingle beach?

Answer 144

Accumulation of sediment- in form of beach, tombolo, bar (e.g. Chesil beach- tombolo, Slapton- onshore bar).

Question 145

Describe the formation of a shingle beach (3)

Answer 145

1. Past (glacial) -New land emerged (sea moved further out from the coast than we see today) = 'new land'. Sediment accumulates on new land = sediment build up. 2. Present (inter-glacial) -Flandrian Transgression = rapid sea level rise = sediment is pushed up with the sea level (due to sea level having a lot of energy due to increased depth) = more/larger sediment being pushed up beach (larger sediment than we would see today = how we know), able to be picked up and deposited at coastline. 3. Future -Increased sea levels (onshore bars/tombolo being breached) waves have more kinetic energy and stormier conditions/shingle is being sorted = moving in direction of the prevailing wind.

Question 146

What is a fjord?

Answer 146

A submerged glacial valley.

Question 147

Describe the formation of a fjord (3)

Answer 147

1. Past (glacial) -Glaciers have huge erosive powers (heavy and ice has a huge force) = able to carve out valleys (break through interlocking spurs). Form at top of mountains which then slowly move down due to gravity. 2. Present (inter-glacial) -Rapid sea level rise (Flandrian Transgression) = glacial valley inundated with sea water- very deep (1,000m) = high marine erosion (but water not breach valleys as steep). 3. Future -Widening/deepening of fjord (sea level rise continue)- marine erosion increase (stormier conditions/deeper water)- banks change profile (more gentle) due to sub-aerial processes (weathering)- warmer temperatures = more biological/chemical weathering (Vant Hoff) = gentler sloping sides.