Coasts

NEED TO KNOW

What percentage of the world’s population live in coastal lowlands (<10m above sea level)?

12%

What is the acronym for the littoral zone order (starting at the cliffs)?

BFNO

Which two parts of the littoral zone are mostly subject to erosion?

Foreshore, nearshore

How long is the UK coastline?

30,000km

Which side of the Tee’s Exe line can rocky coasts be found?

West

Rocky coasts are subject to _ pressure _ storms, with prevailing winds blowing _

low, Atlantic, SW

What rock type is typically found at rocky coasts?

Igneous, metamorphic

Is the littoral zone of a rocky coast narrow or wide?

narrow

Give an example of a coastal plain

The Wash (East Anglia)

What shelters the wash from prevailing winds?

North Sea bay and estuary

Give an example of an igneous rock

granite

Give an example of a metamorphic rock

Slate

Give an example of a sedimentary rock + where it can be found

Boulder clay (glacial till), Holderness

What is the annual recession rate of boulder clay?

1-10 meters

What is the annual recession rate of sandstone (e.g. at Devon)?

1cm-1m

What is the annual recession rate of limestone (e.g. at Dorset)?

1mm-1cm

What is the annual recession rate of granite (e.g. Cornwall)?

1mm

Which type of bedding angle/ strata produces the most unstable cliffs?

seaward dipping

What type of strata is the most stable, as it does not allow for undercutting of rock?

Inland dipping

Give an example of a concordant coastline

Southern coast of the isle of purbeck

At concordant coasts, small coasts often form e.g. _ _ , Dorset

lulworth cove

What feature forms when a resistant rock is finally eroded, allowing the sea to break through to the less resistant rock behind?

Coves

Coves and bays are often formed by differential erosion, which means what?

Erosion that occurs at different rates

Is Croatia’s Dalmatian coast concordant or discordant?

Concordant

Are haff coasts a concordant or discordant feature?

Concordant

Give an example of a haff coast

Curonian lagoon and spit

How long is the Curonian barrier beach?

98km

What features are found at discordant coasts?

Headlands and bays

How frequent are constructive waves?

6-9 per min

How frequent are destructive waves?

11-16 per min

What is beach morphology like in summer?

Constructive waves > sediment moved onto beach by swash > steeper beach profile

What is beach morphology like in winter?

Destructive waves > sediment moved off beach by backwash to offshore bars

Where are larger pebbles found (where the berm forms)?

Upper beach

In the last century, granite at Land’s end has eroded by how much? (far less than holderness- 120m)

10cm

What is the degree/gradient of the slope at a wave cut platform?

<4 degrees

Name three ways sediment can be supplied

Rivers, constructive waves, sub- areal processes

Where waves arrive parallel to the shoreline, what type of beach is formed?

Swash- aligned

Where waves attack the beach at an angle, driven by prevailing winds, longshore drift occurs, forming what type of beach?

Drift- aligned

Can LSD cause beach erosion if sediment supply is disrupted updraft?

Yes

Where has LSD caused severe beach erosion?

Benin, West Africa

Significant eastward LSD in Benin has resulted in Cotonu coastline receding by how many meters per year?

10

Why is Benin’s beach not replaced by updrift LSD?

Ghana’s Akosombo Dam

Ghana’s dam interrupts what percentage of Benin’s sediment supply?

90%

Name the depositional landforms

Cuspate foreland, spit, beaches, offshore bars, barrier island, tombolo

Give an example of a barrier island

Vlieland, West Frisian Islands

What is biostabilisation?

Where vegetation stabilises loose sediment

How does biostabilisation occur?

Roots bind sediment, stems and leaves protect from erosion

Give an example of a depositional landform protected by biostabilisation

Loe Bar, Cornwall

What term describes plants tolerant of saltwater?

halophytes e.g. sand marshes

What term describes plants tolerant of dry conditions?

xerophyte e.g. sand dunes

What is plant succession?

When one species of plant is replaced by another

During plant succession, bare sediment is colonised by plants known as…

pioneer species

At the end of plant succession, what is the final plant community referred to? (adapted to the climate of the area)

Climatic climax community

What is the correct acronym for a psammosere? (sand dune ecosystem)

EFYGDM

Name a xerophyte that also happens to be a pioneer species along fore and yellow dunes

Marram grass

Marram grass roots are long (_m) so that they can reach the water table far below the dry surface

3m

Marram grass grows fast (_m/yr), to avoid burial by sand deposition

1m

What term describes the accumulation of layers of sand?

Accretion

What is a halosere?

Coastal salt- marsh ecosystem

What term describes a length of coastline within which sand movement is mostly contained? (closed system)

sediment cell

What is a sediment budget?

The amount of sediment within a cell

Sediment cells are closed systems, except for:

suspension during large storms, beach nourishment

How many major sediment cells are there across England and Wales?

11

What is sediment cell 5 called?

Christchurch bay, Dorset

Sediment cells maintain a state of _ _

dynamic equilibrium

What type of feedback brings a sediment cell back to balance? (e.g. storms)

Negative

Positive feedback within sediment cells can be caused by hard engineering, such as:

groynes

Weathering occurs _ _

in situ

Freezethaw weathering occurs when the water inside of the cracks reaches _ degrees

0 degrees

Soil creep is an example of a very slow type of mass movement, moving _cm per year

1cm

Why is mass movement common around the UK?

Frequent wave undercutting of weathered cliffs and rainwater adding weight

Rock falls occur on slopes of over _ degrees

40 degrees

Solifluction occurs where the bottom layer is made of _

permafrost

What factors affect mass movement?

Vegetation cover, geology, groundwater

Define eustatic change

The sea level rises/ falls

Define isostatic change

The land rises/ falls, relative to the sea

Eustatic change is global, is it quick or slow?

quick

After the last glacial period, more water was stored as land ice, resulting in…

higher sea levels

Isostatic change is local, is it quick or slow?

Slow

What causes isostatic change?

Isostatic subsidence followed by isostatic recovery

What is isostatic subsidence?

Where the wight of an ice sheet pushes continental crust into the asthenosphere

What is isostatic recovery?

Where the ice melts, removing the weight and the crust returns to its original position

Land in the NW of the UK, which was covered by ice sheets during the last ice age, is still rising at a rate of 2mm per year due to _ _

Isostatic recovery

Land in the SE of the UK, not covered by an ice sheet in the previous ice age, is sinking at a rate of _mm per year

1mm

Name an emergent coastline (caused by isostatic recovery)

Pladda, Scotland

Name two features of an emergent coastline

Raised beach, fossil cliffs

Name a submergent coastline

The Fal estuary, Cornwall

Name three features of submergent coastlines (caused by eustatic change)

Fjord, Rias, Dalmatian coasts

Name two causes of short term SLR

tectonic activity, climate change

Explain where/how tectonic movement caused rapid SLR following a tsunami

Boxing Day tsunami 2004, Japan, caused the sea bed to rise along subduction zones > some crust sank

Coseismic subsidence at Banda Acah caused sea levels to rise how much? (isostatic)

1meter

What is Brady seismic subsidence? (isostatic)

Slow volcanic subsidence, emptying of a magma chamber

The Roman city of _, is largely submerged under the gulf of Naples due to which type of subsidence?

Baiae, bradyseismic

Over the last 20 years, sea levels have risen by _mm/ year

3.2mm

What are the two mechanisms behind contemporary climate change?

Thermal expansion, melting land ice

50% of SLR associated with climate change is due to thermal expansion. Explain this

seawater expands as temperatures increase > greater volume of water

The Nef glacier, Chile has retreated _km since when? (due to land ice melt)

3km, 1930s

From 1870-2010, sea levels rose by _cm (eustatic change)

21cm

Tuvalu is a South Pacific oceanic region, made up of how many atolls

9