Coasts

Question 1

What are submergent coastlines?

Answer 1

Being submerged, relative sea level rising, estuaries formed in drowned river mouths eg Dalmatian Coast, Croatia

Question 2

What are emergent coastlines?

Answer 2

Land emerging from water, relative sea level falling, tectonics or isostasy responsible for most types eg Isle of Arran, Scotland

Question 3

What are coastal plain coastlines?

Answer 3

low energy coasts where depositional landforms found, likely made of sedimentary rock eg Bamburgh beach

Question 4

what are rocky coastlines?

Answer 4

high energy coasts where erosional landforms found, likely made of igneous or metamorphic rock eg Bedruthen steps

Question 5

What are high energy coastlines?

Answer 5

Exposed coasts facing prevailing winds with long wave fetched resulting in powerful waves, generally have rocky coasts, where rate of erosion exceeds rate of deposition eg Old Harry’s rocks

Question 6

What are low energy coastlines?

Answer 6

Sheltered coasts with limited fetch and low wind speeds resulting in small waves, generally have sandy coasts, where rate of deposition exceeds rate of erosion eg Flamborough head

Question 7

what are depositional coastlines?

Answer 7

Developed where sediments accumulate either from a local source or after being transported to the area in rivers and glaciers or by ocean currents and waves; these include deltas, mangrove swamps, salt marshes, barrier islands, and beach-sand dunes eg Spurn head

Question 8

what are erosional coastlines?

Answer 8

Developed where active erosion by wave action occurs or where rivers or glaciers caused erosion when sea level was lower than it presently is, includes cliffs or rocky shores eg Lands end

Question 9

what are primary coastlines?

Answer 9

Dominated by land based processes such as deposition at the coast from rivers or new coastal land formed from lava flows.

Question 10

what are secondary coastlines?

Answer 10

Dominated by marine erosion or deposition processes where sea movement causes accumulation of ocean sediments in a single place. Examples include barrier islands, mud flats and coral reef ecosystems.

Question 11

what is the tees exe line?

Answer 11

a line dividing the uk, to the north/west of it rock is harder, older, igneous or metamorphic, and high energy rocky coasts and mountains are found, to the south/east rock is softer, younger, sedimentary, and lowlands and low energy coastal plain coasts found

Question 12

give examples of sedimentary rock

Answer 12

sandstone, limestone, shale

Question 13

give examples of igneous rock

Answer 13

basalt, granite

Question 14

give example of metamorphic rock

Answer 14

marble, slate

Question 15

what 4 factors affect coastal erosion?

Answer 15

rock type, rock structure, wave type, coastline shape

Question 16

what is a discordant coastline?

Answer 16

rock layers are perpendicular to the coast so headlands and bays form

Question 17

what is a concordant coastline?

Answer 17

rock layers are parallel to the coast so coves form

Question 18

how does vegetation stabilise sand dunes?

Answer 18

winds move sediment up the beach by saltation, which gets trapped by seaweed at the strand line, forming an embryo dune which is colonised by pioneer species eg lyme grass, stabilising the dune. this process is repeated forming more dunes - fore dunes and yellow dunes (marram grass comes in here) and grey dunes. further up the beach, nutrients, moisture, hummus, stability and ph increase while salinity decrease, so more plants outcompete the pioneer species until climatic climax is reached

Question 19

how does vegetation stabilise salt marshes?

Answer 19

mud is deposited in low energy environments, and salt tolerant plants begin to colonise and stabilise the mud flat, then halophytes eg cordgrass slow down tidal flow, trapping more mud and silt, and as mud rises it is less covered by water so plants eg meadowgrass outcompete pioneer species and less salt tolerant plants can survive further up the marsh as it becomes less saline, more fertile and has more organic matter

Question 20

describe constructive waves

Answer 20

stronger swash than backwash so they deposit sediment, less frequent, creates berm and gently sloping beach, long wavelength, dominate in summer

Question 21

describe destructive waves

Answer 21

stronger backwash than swash so erode sediment, frequent, destroys berm and creates offshore bar, short wavelength, sloping beach, dominate in winter

Question 22

explain hydraulic action

Answer 22

waves crash against cliff trapping air in rock joints, which compresses and expands when wave retreats, weakening rock joint

Question 23

explain wave refraction

Answer 23

the process by which wave crests bend to be parallel to the coast. waves move slower in shallower water, so wave crests bend until all parts of the wave are at an equal depth, resulting in the convergence of wave energy on headlands, and diverging at bays, so more erosion at headland

Question 24

explain the sediment cell

Answer 24

sediment cells are systems of sources, transfers and sinks. there is a sediment budget within a cell, and cell act to reach dynamic equilibrium - if budget falls, transportation and erosion occurs (pos feedback), if budget increases, more deposition occurs (neg feedback)

Question 25

mechanical weathering

Answer 25

freeze thaw, salt cracking, wetting and drying

Question 26

explain salt weathering

Answer 26

when salt water evaporates, it leaves salt crystals behind, which can grow over time causing stresses in the rock, causing it to break

Question 27

biological weathering

Answer 27

plants growing roots into cracks in rock

Question 28

chemical weathering

Answer 28

acid rain and sea spray

Question 29

explain soil creep

Answer 29

the slow downward movement of individual soil particles

Question 30

what is weathering

Answer 30

the gradual breakdown of rock in situ

Question 31

what is mass movement

Answer 31

the movement of material downslope due to gravity

Question 32

explain slumping

Answer 32

• Slumping causes rotational scars, and repeated slumping creates terraced cliff profiles.
  o Slumping occurs in more saturated conditions, on moderate to steep slopes, and is common where softer, more permeable materials overlie harder less permeable rock.
  o Rock slumps down along a curved rock plane.
  o There is a rotational movement in slumping which exposes a rotational scar - a fresh, curved, unvegetated rock surface on a cliff face.
  o This forms terraced cliff profiles

Question 33

explain rockfalls

Answer 33

• Rockfalls form talus scree slopes.
  o Rockfalls commonly occur when strong, steep cliff faces with lots of jointed are exposed to mechanical weathering, on slopes over 40º.
  o The material that breaks off the cliff falls down to form scree (also known as talus) at the bottom of the cliff.

Question 34

explain rock slides

Answer 34

• Rock slides form talus scree slopes.
  o Jointed rocks, or cliffs with bedding planes roughly parallel to the slope or cliff surface, are susceptible to landslides.
  o Blocks of rock move downslope on a slip plane.
  o Scree is formed at the foot of the slope.

Question 35

explain isostatic sea level change

Answer 35

1. During an ice age layers of snow fall and build up on the land.
2. The snow then freezes into ice
3. The weight of the land causes the crust to ‘sink’ under the weight (isostatic subsidence).
4. This causes the sea level to rise.
5. The ice begins to melt into the sea at the end of a glacial period
6. Reduced weight of the ice causes the land to readjust and rise (isostatic recovery)
7. Isostatic recovery is a slow process which takes place over numerous years.
8. The sea level decreases.

Question 36

explain eustatic sea level change

Answer 36

1. Millions of people drive petrol and diesel cars everyday
2. Increasing concentrations of Greenhouse gases are present in the atmosphere
3. The enhanced greenhouse effect - the atmospheric temperature rises over time
4. This high temperature causes the Antarctic ice sheets and glaciers to melt
5. This increases the volume of water in the oceans
6. World average sea levels rise
7. This floods low-lying areas, for example the Maldives and the south of Bangladesh

Question 37

explain steric sea level rise

Answer 37

1. Temperature of the water increases.
2. This means the particles have more energy.
3. This causes the particles to move faster.
4. This causes them to spread out more.
5. Therefore the water has more volume.
6. And hence has expanded.
7. This causes the sea level to rise.
8. This accounts for 70-75% of Sea Level Rise.

Question 38

what are relict cliffs?

Answer 38

old cliffs displaying features such as caves, arches and stack

Question 39

what are raised beaches?

Answer 39

Areas of former wave-cut platforms and their beaches which are at a higher level than the present sea level due to isostatic uplift. eg Isle of Arran

Question 40

what is a ria?

Answer 40

a drowned river valley, flooded as sea levels rise, while higher land remains exposed eg kingsbridge estuary, devon

Question 41

what is a fjord?

Answer 41

a drowned glacial valley - as sea levels rise, U shaped valleys often 1000m deep left by glaciers are submerged eg Loch torridon, Scotland

Question 42

what is a fjard?

Answer 42

a flooded glacial lowland - formed by the submergence of formerly glaciated valleys

Question 43

what are dalmatian coasts?

Answer 43

when synclines on a concordant coast are eroded leaving islands where anticlines are eg Croatia

Question 44

factors affecting coastal recession

Answer 44

• Storms
  
  • High energy coast
  • Destructive waves - long fetch
  • Soft/weak geology
  • Sea level rising/ submerging coast
  • Lots of sub-aerial processes - weathering and mass movement
  • Narrow beaches

Question 45

why is bangladesh at risk from floods?

Answer 45

sediment starved by dams, mangroves removed, isostatic readjustment causing it to be pushed down as himalayas spring up

Question 46

give methods of hard engineering

Answer 46

sea wall, groyne, revetments, rock armour

Question 47

give methods of soft engineering

Answer 47

beach nourishment/replenishment, managed retreat

Question 48

what is integrated coastal zone management (ICZM)

Answer 48

managing complete sections of coast as a whole rather than by individual towns, bringing together all players

Question 49

what is a shoreline management plan (SMP)

Answer 49

when all local interest groups are consulted and plans are decided on - either do nothing, hold the line, advance the line or retreat the line

Question 50

How do spits form?

Answer 50

Spits are formed where the prevailing wind blows at an angle to the coastline, resulting in longshore drift, which causes sedimtent to be deposited at the end of a beach, forming a spit

Question 51

How do tombolos form?

Answer 51

Wave refraction around an offshore island creates an area of calm water so deposition occurs between the island and the coast. LSD also occurs.

Question 52

How do bars form?

Answer 52

A spit grows so long that it extends across a bay eg Chesil beach

Question 53

How do cuspate foreland form?

Answer 53

Commonly accepted answer is that two spits are growing from opposite directions eg Dungeness, Kent