Own Knowledge - Coasts

Question 1

define fetch

Answer 1

the distance over which the wind has been blowing - stronger winds = longer fetch = more powerful winds

Question 2

destructive waves

Answer 2

• formed from strong winds over long fetches
• cause coastal erosion
• break at a high frequency = 11-15 waves a minute
• backwash stronger then swash = erosion
• forms narrow + steep beaches

Question 3

constructive waves

Answer 3

• light winds + short fetches
• deposition
• low in height
• break at a low frequency = 6-9 waves break/ crests per minute
• swash stronger than backwash
• forms wide + shallow beaches

Question 4

discordant coastline

Answer 4

bands of resistant and less resistant rock type run at right angles / perpendicular to the coastline
- forms headlands + bays

Question 5

concordant coastline

Answer 5

• bands of rock run parallel to coastline

Question 6

headlands

Answer 6

• discordant coastline = eroding at different rates depending on rock type
• the harder rocks eg. CHALK = less resistant to erosion
• these areas stand out as prominent rocky headlands

Question 7

bays

Answer 7

• discordant coastline
• softer rocks eg. MUDSTONE erode more quickly
• erode back to form a bay eg SWANAGE BAY

Question 8

what is a cove

Answer 8

a circular area of water with a narrow entrance from the sea

• formed from harder rock being breaches through lines of weakness such as faults and joints
• soft rock exposed = soft rock is eroded

Question 9

where do caves stacks and arches usually form

Answer 9

headlands

Question 10

how is a cave formed

Answer 10

• a destructive wave breaks against headlands attacking joins + cracks
• these waves erode the rock through hydraulic action and abrasion
• erosion will widen the crack = eventually form a cave

Question 11

how is an arch formed

Answer 11

• waves continually attack cabe through HYDRAULIC ACTION + ABRASION
• when a waves breaks it blocks off entrance + traps air
• the trapped air is compressed increasing pressure
• pressure from waves caused back of cave to be eroded through
• forming an arch

Question 12

how is a stack formed

Answer 12

• continues erosion by the sea widens arch
• as the sea undercuts base = more pressure on top of arch
• weakened roof of arch collapsed = stack
• stack = pinnacle of rock separated from mainland

Question 13

how is a stump formed

Answer 13

continued weathering and erosion of the stack

Question 14

how is a cliff + wave cut platform formed

Answer 14

• destructive waves attack the land between HIGH AND LOW WATER MARKS
• through hydraulic action + abrasion, the waves undercut the cliff causing a WAVE CUT NOTCH
• as the notch gets deeper, the overhanging cliff is unsupported and collapses
• repeat = retreat
• a gently sloping rocky area is left at the bottom of a retreating cliff = WAVE CUT PLATFORM
• covered at high tide but exposed at low tide

Question 15

types of mass movement

Answer 15

rock falls - happen suddenly when a piece of rock falls from a cliff that has been weathered or undercut

slumping - occurs after long periods of rain. the rain seeps through soil and permeable rocks eg. SANDSTONE. at the junction when impermeable meets permeable , the saturated rock slumps in a rotational manner

sliding - occurs along a flat surface eg. bedding plane

Question 16

direction of prevailing winds in UK

Answer 16

south-westerly

Question 17

long shore drift

Answer 17

• process of transportation that moves sand and pebbles along the coast
• the swash carries the sand up the beach at the same angle as the prevailing winds
• the backwash then draws the sediment back down the beach at RIGHT ANGLES
• zigzag movement

Question 18

how are beaches formed

Answer 18

• when eroded material is transported and deposited by constructive waves along the coastline

Question 19

what did the bar in slapton create

Answer 19

a lagoon - Slapton Leys

Question 20

how does a spit form

Answer 20

• long and narrow ridge of sand or shingle - one side attached to land
• material is transported along a beach due to longshore drift
• when the coastline bends round, the sediment is deposited on the seabed
• gradually more and more is deposited - forming a ridge that extends into sea
• as the ridge extends, the tip is affected by winds as waves approach from different directions
• causes the spit to curve

Question 21

how does a bar form

Answer 21

a bar is a ridge of sand or shingle across the entrance to a bay or river mouth

• material is transported along the beach via LSD
• deposition continues in a straight line, directly across entrance to bay
• fresh or slightly salty water is trapped behind to form a LAGOON

Question 22

human causes of coastal changes

Answer 22

settlements 
tourism - groynes to maintain tourist beaches = increases erosion further down coast
infrastructure - hard engineering 
construction 
agriculture

Question 23

effects of sea level rise

Answer 23

• cliffs will continue to retreat

- areas of ‘soft coastline’, may erode more often/ at a faster rate

Question 24

what is integrated coastal zone management

Answer 24

a way to manage the coast and the land behind it sustainably, by involving everyone who uses it

Question 25

types of coastal management

Answer 25

no intervention
hold the line - maintain the existing shoreline by building defences
managed / strategic realignment - allow the shoreline to change naturally, but manage and direct the process
advance the line - build new defences on the seaward side

Question 26

hard engineering

Answer 26

• groynes

- sea walls

Question 27

soft engineering

Answer 27

• beach replenishment

- slope stabilisation

Question 28

what do hard engineering strategies aim to do

Answer 28

deflect or absorb the waves energy by building barriers

Question 29

what is managed retreat

Answer 29

• a shoreline is allowed to retreat but actions taken to minimise the impact

Question 30

advantages and disadvantages of rock armour

Answer 30

advantage
- cheap

disadvantage

• ugly
• undermined by shingle and sand

Question 31

advantages and disadvantages of sea wall

Answer 31

advantages

• protects base of cliffs
• made of resistant concrete
• if ‘recurved’ it reflects energy

disadvantages

• expensive
• restricts beach acess
• ugly

Question 32

advantages and disadvantages of groynes

Answer 32

advantages

• builds a wide beach
• attracts tourists

disadvantage

• high maintenance = wood rots
• sand prevented from moving so can cause erosion further along

Question 33

advantages and disadvantages of beach replenishment

Answer 33

artificially adding to the amount of material on a beach to protect the back of a beach or cliff from wave attack

advantages

• looks natural
• beach attracts tourists
• chepa

disadvantages
- replacement of sediment needed regularly

Question 34

advantages and disadvantages of slope stabilisation

Answer 34

a useful soft engineering strategy to employ on cliffs that are prone to mass movement processes = technique used to prevent slumping and erosion .

drains are installed at the the top low the cliff to remove groundwater, preventing rocks from becoming saturated

advantages

• prevents mass movement
• keeps cliff in place
• safer for people on the beach

disadvantages

• difficult to install
• expensive