2B.3 Rates of Coastal Recession

Question 1

name the three rock types

Answer 1

igneous
metamorphic
sedimentary

Question 2

igneous rock

Answer 2

e.g. granite, basalt, dolerite
-interlocking crystals cause erosion rate to be very slow
-granite has few joints, limiting weaknesses available for erosion to exploit

Question 3

metamorphic rock

Answer 3

e.g. slate, marble
-crystalline rocks are resistant to erosion
-some have a feature with the same direction crystals, causing weaknesses
-folded and heavily fractured for erosion to exploit rocks, erosion is slow

Question 4

sedimentary rock

Answer 4

e.g. sandstone, shale, chalk and limestone
-erodes faster than others
-younger rocks are weaker
-bedding planes and fractures create vulnerability to erosion

Question 5

what is the weakest coastal material

Answer 5

unconsolidated sediment

Question 6

what factor of rocks influences cliff profiles

Answer 6

PERMEABILITY

Question 7

permeable rocks

Answer 7

allow water to flow through e.g. sandstone and limestone

Question 8

impermeable rocks

Answer 8

do not allow groundwater flow e.g. clays, mudstones

Question 9

how can impermeable rocks become weak?

Answer 9

groundwater flow weakens rocks as it removes cement that binds sediment together in the rock
-also it creates a high pore water pressure, making the rock heavy, affecting its stability

Question 10

describe a dalmation coastline

Answer 10

-concordant coastline
formed due to a rise in seal level, the tops of ridges can be seen above sea level which creates a series of offshore, long, thin islands

Question 11

describe a haff coastline

Answer 11

-concordant coastline
it is enclosed by low lying sandy spits or dunes which are aligned parallel to the coast
-longshore drift occurs

Question 12

describe a fjord

Answer 12

-discordant coastline
formed when deep glacial troughs flood by rising sea levels, cutting deep valleys perpendicular to the coastline, they are very deep
-found in Norway and west Iceland

Question 13

describe a ria

Answer 13

-discordant coastline
these are drowned river valleys which are sheltered winding inlets formed by rising sea level, they are narrow and form natural harbours at the coast
e.g. Falmouth is the deepest natural harbour in the UK

Question 14

what vegetation is found on a haff coastline?

Answer 14

marram grass

Question 15

marram grass adaptations and features

Answer 15

it is a common type of grass that has a waxy, hard coating
-durable to winds and storms
-rounded tube shape to retain moisture
-deep roots to access more water
-wide roots for stability and reaching minerals and water
-halophyte plant with salt spray

Question 16

stability

Answer 16

the protection of coastlines by vegetation such as sand dunes and salt marshes

Question 17

succession

Answer 17

the changing nature of a plant community over time as an area is colonised

Question 18

psammorsene

Answer 18

the succession of plants that develop on a sand dune complex

Question 19

flocculation

Answer 19

the process by which river’s load of clay and silts carried in suspension is deposited more easily as it meets with sea water (salt)

Question 20

halosene

Answer 20

the succession of plants that develop in a salt marsh

Question 21

how do sand dunes play a role in the coast

Answer 21

it protects the coastal landscape from erosion by stablising plants
-they are important buffer zones between the sea and land, they take the impact of storms, reducing the impact on the land

Question 22

describe how vegetation stabilises coastal deposition features

Answer 22

1. plant roots bind sediment together, reducing erosion
2. when submerged, plants provide a protective layer so the surface of sediment is not directly exposed to moving water (salt marshes)
3. plants protect sediment form wind erosion, reducing speed at the surface with friction against the vegetation

Question 23

how are halophytes salt tolerant?

Answer 23

they store water in special tissue with air spaces
-some excrete salt through glands or by dropping yellow leaves where salt has been accumulated
-they retain water- succulents

Question 24

how are xerophytes dry condition tolerant?

Answer 24

they have thick cuticles to stop uncontrolled evaporation, with a small leaf surface area too
-low stomata density
-sunken stomata maintains humid air
-stomatal hairs
-rolled leaves
-extensive roots maximise water uptake

Question 25

when is a climax community reached?

Answer 25

when the vegetation is in a state of equilibrium with the environment

Question 26

name 3 wind processes

Answer 26

suspension, impact creep, saltation

Question 27

describe suspension

Answer 27

moves fine grains of sand in the water (1%)

Question 28

describe impact creep

Answer 28

moves the heaviest grains in water (4%)

Question 29

describe saltation

Answer 29

moves intermediate sand grains (95%) -in WATER AND ON BEACHES

Question 30

name the 5 stages of sand dune formation

Answer 30

-embryo/ fore dunes -yellow dunes -grey dunes -dune slacks -woodland

Question 31

describe the embryo and fore dune stage

Answer 31

mobile dunes -plants have waxy leaves to retain moisture and withstand strong winds, high salt tolerance -offshore winds cause sand to build up slowly, it accumulates above the high tide line, causing a colonisation of grasses -dead marram grass adds organic matter and nutrients to the soil

Question 32

describe the yellow dune stage

Answer 32

mobile dunes -vegetation develops on the upper and back dune surfaces, stabilising the system -surface is being blown away and replenished with new sand -once stable conditions occur, mosses and cover patches

Question 33

describe the grey dune stage

Answer 33

fixed dune -more soil is trapped with nutrients and moisture -high diversity of species -more plants colonise with more organic matter -dunes may be trampled on or grazed on, organic layer forms on the soil surface

Question 34

describe the dune slack stage

Answer 34

fixed dune -moisture loving plants colonise here -there is a damp environment, with a high water table in winter -plants receive nutrients leached from the surrounding dunes -is now rich will local and national rare species

Question 35

describe the woodland stage

Answer 35

sandy soils have developed that can support scrub heaths of willow and other trees -acidic soils and high organic matter content -cattle or grazing pressures can prevent woodland development -vegetation is dominated by plants that are adapted to grasslands and heathlands.

Question 36

aeolian processes

Answer 36

wind processes

Question 37

what type of landforms are sand dunes and salt marshes

Answer 37

depositional landforms

Question 38

salt marshes

Answer 38

areas of flat, silty sediment from rivers that accumulate around estuaries or lagoons, affected by the sea

Question 39

fluvial

Answer 39

river processes

Question 40

characteristics of salt marshes

Answer 40

-sheltered environment -salt and freshwater meet -no strong currents or tides, so deposition and accumulation occurs

Question 41

describe the flocculation process

Answer 41

as clay and silt are carried in suspension, they are deposited easily as they meet with salt in sea water -clay particles are small and negatively charged (remain suspended) -in the estuary, river water mixes with sea water, so the charges on clay particles are neutralised, they flocculate (stick together) and settle out (sedimentation) -building up a muddy shore in an estuary

Question 42

why must wave energy be low in salt marshes?

Answer 42

low energy must be present for a salt marsh to develop, so sea water can deposit the smaller clay particles and so they cling to eachother in flocculation e.g. behind spits, in bays or on the top of long flat beaches

Question 43

describe the development of salt marshes

Answer 43

1. first colonised by algae which helps to stabilise the surface of mud and reduce erosional processes by waves and tides 2. the colonisation of glassworts stabilises the mud, adding organic matter so vegetation can grow 3. this interrupts the flow of water, encouraging more deposition

Question 44

name 5 stages of salt marsh succession

Answer 44

algal stage pioneer stage establishment stage stabilisation climax vegetation

Question 45

when are salt marshes covered and exposed?

Answer 45

they are covered at high tide and exposed at low tide