Coasts key words

Question 1

Littoral zone

Answer 1

the wider coastal zone including adjacent land areas and shallow parts of the sea just offshore. split into the - backshore, foreshore, nearshore, offshore.

Question 2

Cliff profile

Answer 2

the height and angle of a cliff face as well as its features, such as wave-cut notches or changes in slope angle.

Question 3

Coastal accretion

Answer 3

The deposition of sediment at the coast and seaward growth of the coastline, creating new land. It often involves sediment deposition being stabilised by vegetation.

Question 4

Dynamic equilibrium

Answer 4

The balanced state of a system when inputs and outputs balance over time. If one element of the system changes because of an outside influence, the internal equilibrium of the system is upset and other components of the system change. By a process of feedback, the system adjusts to the change and the equilibrium is regained.

Question 5

Holocene

Answer 5

The geological epoch began about 12,000 years ago at the end of the last Pleistocene ice age. Its early stages were marked by large sea level rises of about 35m and a warming interglacial climate.
Dalmatia, Croatia, in the Adriatic Sea was drowned by sea level rise during the Holocene.

Question 6

Faults

Answer 6

Major fractures in rocks produced by tectonic forces and involving the displacement of rocks on either side of the fault line.

Question 7

Unconsolidated sediment

Answer 7

Material such as sand, gravel, clay and silt that has not been compacted and cemented to become sedimentary rock (not undergone process of lithification and so is loose and easily eroded)

Question 8

Pore water pressure

Answer 8

The pressure water experiences at a particular point below the water table due to the weight of water above it.
High pore water pressure causes cliffs to become more unstable.

Question 9

Fetch

Answer 9

The uninterrupted distance across water over which a wind blows, and therefore the distance waves have to grow in size.

Question 10

Swash

Answer 10

The flow of water up a beach as a wave breaks

Question 11

Backwash

Answer 11

When water runs back down the beach to meet the next incoming wave.

Question 12

Beach morphology

Answer 12

The shape of beach, including its width and slope (the beach profile) and features such as berms, ridges and runnels. It also includes the type of sediment (shingle, sand, mud) found at different locations on the beach.

Question 13

Blow hole

Answer 13

Forms when a coastal cave turns upwards and breaks through the flat cliff top. Usually, this is because of erosion of especially weak strata or the presence of fault line.

Question 14

Currents

Answer 14

Flows of seawater in a particular direction driven by winds or differences in water density, salinity or temperature. Some are almost continuous, such as those that form the global thermohaline circulation, and others are more sporadic, such as longshore currents, while some last only for a few hours, such as rip currents.

Question 15

Mass movement

Answer 15

The downslope movement of rock and soil; it is an umbrella term for a wide range of specific movements including landslide, rockfall and rotational slide.

Question 16

Isostatic change

Answer 16

A local rise or fall in land level. e.g. isostatic readjustment

Question 17

Eustatic change

Answer 17

Involves a rise or fall in water level caused by a change in the volume of water. This is a global change, affecting all of the world’s connected seas and oceans.

Question 18

Accretion

Answer 18

This occurs when sediment is added to a landform, such as a river delta, by deposition. It can build up to form new land, allowing a delta to grow out to sea. It tends to be balanced by subsidence, caused by the weight of newly deposited sediment.

Question 19

Post-glacial isostatic adjustment

Answer 19

Refers to the uplift experienced by land following the removal of the weight of ice sheets. It is sometimes called post-glacial rebound or post-glacial re-adjustment.

Question 20

Ria

Answer 20

A drowned river valley in an unglaciated area caused by sea level rises flooding the river valley, making it much wider than would be expected based on the river flowing into it.

Question 21

Barrier islands

Answer 21

Offshore sediment bars, usually sand dune covered but, unlike spits, they are not attached to the coast. They are found between 500m and 30km offshore and can be tens of kilometres long.

Question 22

Dredging

Answer 22

Involves scooping or sucking sediment up from the seabed or a river bed, usually for construction sand or gravel, or to deepen a channel so that large boats can navigate it.

Question 23

Dissipation

Answer 23

The term used to describe how the energy of a wave is deceased by friction with beach material during the wave swash up the beach.
A wide beach slows waves down and saps their energy so, when they break, most energy has gone.

Question 24

Megaproject

Answer 24

A very expensive (over US$1 billion), technically difficult and usually long-term engineering project. Many megaprojects have multiple aims and often large environmental.

Question 25

Return period (or recurrence interval)

Answer 25

Refers to the frequency of a flood of a particular magnitude. A 1:100 flood event will occur, on average, every 100 years (there is a one per cent chance of that flood occurring in a given year)

Question 26

Environmental refugees

Answer 26

Communities forced to abandon their homes due to natural processes including sudden ones, such as landslides, or gradual ones, such as erosion or rising sea levels.

Question 27

Conflict

Answer 27

In the context of coastal management, conflict means disagreement over how the coast should protected from threats and which areas should protected. Conflict often exists between different stakeholders, such as residents versus the local council.

Question 28

Littoral cells/sediment cells

Answer 28

All coastlines divide up into distinct littoral cells containing sediment sources, transport paths and sinks. Each littoral cell is isolated from adjacent cells and can be managed as a holistic unit.

Question 29

Outflanking

Answer 29

Occurs when erosion gets behind coastal defences at the point where they stop, leading to rapid erosion inland and undermining of defences.

Question 30

Processes of erosion

- explanation & influence of lithology

Answer 30

Hydraulic action (wave quarrying)

• Air trapped in cracks and fissures is compressed by the force of waves crashing against the cliff face.
• Pressure forces cracks open, meaning more air is trapped & greater force experienced in the next cycle of compression.
• This processes dislodges blocks of rock from the cliff face.

Question 31

Wave-cut notch

Answer 31

Curved indentation that forms between high tide & low tide marks, where destructive waves impact against the cliff, extending along the base of the cliff.

Eroded by HA & abrasion

Question 32

Wave-cut platform

Answer 32

flat rock surface exposed at low tide, extending out to sea from base of cliff. shows former cliff position.
- Marine erosion between high & low tide mark by HA/abrasion forms wave cut notch along base.
- Notch deepens by further erosion until overhanging rock collapses as rockfall/by mass movement due to gravity forming cliff.
- Repeated cycles of notch cutting and collapse causes cliff to retreat inland (coastal recession)
- rock just below low tide level always submerged
therefore uneroded (not exposed to wave impact)