Physical landscapes - coasts

Question 1

how are waves formed

Answer 1

wind blows over the sea and friction with water surface causes ripples to form
these develop into waves
shallowing water and rising sea floor affects the wave’s orbital movement, becomes more elliptical
wave crest rises up and eventually breaks

Question 2

constructive waves

Answer 2

low vs length
strong swash and weak backwash
less frequent 6-8per min
produce wide, sandy beaches with a gradual beach angled

Question 3

destructive waves

Answer 3

tall vs length
weak swash and strong backwash
10-14 per min
break downward with great force, eroding the beach to make a steeper angle
pebble beaches often produced

Question 4

mechanical weathering

Answer 4

is the disintegration of rocks
piles of fragments are found at the cliff foot

Question 5

eg salt weathering

Answer 5

type of mechanical
water evaporates, leaves salt crystals which grow and expand, causing pressure on the rock

Question 6

chemical weathering

Answer 6

caused by chemical changes
rainwater slowly dissolves rocks

Question 7

eg carbonation

Answer 7

rainwater absorbs co2 and becomes acidic, when it comes into contact with alkaline rocks such as chalk/limestone a chemical reaction is produced
rocks slowly dissolve

Question 8

mass movement

Answer 8

downward movement of material under the influence of gravity

Question 9

sliding

Answer 9

large blocks of rock slide down a cliff face as a landslide, often triggered by heavy rainfall or earthquakes

Question 10

slumping

Answer 10

involves the collapse of saturated or weak rocks e.g sand or clay, often along a curved surface

Question 11

rock falls

Answer 11

fragments of rock break away from the cliff face to form scree

Question 12

erosion

Answer 12

the wearing away of earth’s surface by the action of wind or water

Question 13

hydraulic action

Answer 13

destructive waves hit the base of cliffs
water enters cracks, joints and faults at high speeds
air in these cracks is compressed with explosive force
this, repeated, causes cracks to widen and the cliff to weaken and material breaks off

Question 14

abrasion

Answer 14

waves have the energy to carry material and at times large rocks
this material is thrown at the cliff face, scratching and scraping the surface

Question 15

attrition

Answer 15

rock fragments carried by the sea collide and become smaller over time
jagged edges are worn away to produce small pebbles

Question 16

traction

Answer 16

largest pieces of material are rolled along the seabed by the force of water
good when there is lots of power in the water

Question 17

saltation

Answer 17

load is bounced along the sea bed e.g shingle
currents cannot keep heavier sediment afloat for longer periods

Question 18

suspension

Answer 18

small particles are carried in the water

Question 19

solution

Answer 19

materials often derived from limestone or chalk are dissolved and carried

Question 20

longshore drift

Answer 20

process by which waves move material along the coast

waves approach the coast at an angle due to the prevailing wind direction
swash carries material toward the beach at an angle
backwash flows back to the sea down the beaches slope at 90 degrees due to gravity
process repeats itself along the coast in a zigzag movement

Question 21

deposition

Answer 21

waves drop and leave behind the load they were carrying
takes place in areas where the flow of water slows down (low sheltered bays)
here the waves lose energy and sediment can no longer be carried
also occurs when water is trapped by landforms such as spits or engineered structures

Question 22

headland

Answer 22

a cliff that juts out into the sea, comprised of hard rock

Question 23

bay

Answer 23

crescent shaped indentation in the coastline, found between headlands

Question 24

bays and headlands formation

Answer 24

form along discordant coastlines where hard and soft rocks alternate along the coast
these erode at different rates and less resistant rock such as clay is worn away
bays are sheltered by headlands and become low energy environments where deposition occurs

Question 25

headland features formation

Answer 25

large crack is enlarged by the on/off pressure of hydraulic action crack grows into a notch and then a cave as destructive waves converge on the headland and continue to erode it over time the cave becomes larger; water refraction draws waves to all sides of the headland so caves may form back to back sea breaks through the back of the caves, cutting through the headland to form an arch - base is widened as notches form weathering weakers the top of the arch which eventually collapses, leaving a pillar of detached rock called a stack notches form at the base of the stack and it becomes unstable eventally topples leaving only its base, the stump

Question 26

wave cut platform formation

Answer 26

sea attacks cliff base between high and low tide mark dent or wave cut notch is formed by erosional processes e.g abrasion and hydraulic action notch increases in size, cliff becomes unstable as it is undercut; materials fall off into the sea as the cliff begins to collapse platform is left - the very base of the cliff below the sea the process repeats and the cliff continues to retreat

Question 27

wave cut platform

Answer 27

area of bedrock at the base of some cliffs, seen at low tide has deep cracks in some places, rock pools, bare rock, may be smoothed by attrition, slopes gently to the sea

Question 28

beaches

Answer 28

deposits of sand and shingle at the coast formed by constructive waves depositing material to build up the beach sand beaches are flat and wide, backwash moves small particles back down to form a gentle slope, mainly found in sheltered bays pebble beaches are steep and narrow; finer sand washed away

Question 29

sand dunes

Answer 29

form on the dry backshore of a sandy beach need a large sand supply, onshore wind, a flat beach and an obstacle embryo dunes form around deposited objects like rocks and wood these develop and become stabilised by vegetation e.g marram grass, form fore dunes and yellow dunes rotting vegetation adds organic matter to the sand increasing fertility - more plants found on back dunes wind can form depressions in the sand - dune slacks - where ponds can form

Question 30

spit

Answer 30

a long, narrow finger of sand/shingle jutting out into the sea from the land form on the coast where there is significant lsd if the coastline changes orientation and bends sharply, sediment is deposited out to sea, building up as an extension from the land strong winds can cause the end of the spit to be curved into a hook mud flats and salt marshes can form in the sheltered land behind

Question 31

bar

Answer 31

spit stretching across a bay by lsd, trapping a freshwater lake or lagoon

Question 32

tombolo

Answer 32

spit stretching out from the mainland to connect an island

Question 33

jurassic coast

Answer 33

located in sw england, coast of channel stretches from bridport to bournemouth, discordant old harrys rock - chalk stump swanage bay - chalk, clay, limestone durdle door - limestone arch

Question 34

hard engineering management strategies

Answer 34

built to alter or defend the environment; include anything designed to prevent cliff erosion along the shore or at the cliff foot

Question 35

sea wall

Answer 35

built along cliff front or beach back, often recurved to relfect waves back on themselves and impede the next

Question 36

sea wall benefits

Answer 36

can last up to 50 years sense of security promenade on top and seating at base doesn't impede the movement of sediement downdrift so no disadvantage to other areas

Question 37

sea wall costs

Answer 37

restrict people's access to the beach unsightly can destroy habitats expensive to build + repair at £5000 per metre

Question 38

rock armour

Answer 38

large boulders of hard rock placed on the cliff base, absorb wave energy

Question 39

rock armour pros

Answer 39

cheap and easy to build long lasting versatile - can lengthen the lifespan of a seawall or stabilise dunes

Question 40

rock armour cons

Answer 40

ugly imported rocks are preferred causing tension need regular maintenance potentially hazardous

Question 41

gabions

Answer 41

rocks and boulders encased in wired mesh, placed at the beach back to absorb and dissipate wave energy

Question 42

gabions pros

Answer 42

cheap and easy to build often constructed on site quick fix and good value blend in well

Question 43

gabions cons

Answer 43

easily destroyed, repairs dangerous to birds and people when damaged unsightly if damaged use is restricted to sandy beaches

Question 44

groynes

Answer 44

wood or stone barriers constructed at right angles to the beach trap material and stop transportation by longshore drift; wide beach is encouraged helping to absorb wave energy and reduce erosion

Question 45

groynes pros

Answer 45

cheap and long lasting larger beach attracts tourists can be used to walk along, or as wind breaks

Question 46

groynes cons

Answer 46

unattractive problem is merely passed on, not halted can be dangerous to kids and surfers restrict walking along the beach

Question 47

soft management strategies

Answer 47

adapt and encourage natural processes to take place

Question 48

beach nourishment

Answer 48

replacement of sediment lost through lsd shingle is dredged from the seabed and pumped

Question 49

beach nourishment pros

Answer 49

natural, blends in, makes a wider beach may attract tourists protects people living along the seafront and expensive properties

Question 50

beach nourisment cons

Answer 50

hiring a dredger is expenive so high overheads access to the beach is restricted for several weeks

Question 51

beach reprofiling

Answer 51

artificial reshaping using existing material bulldozers move shingle up the beach wave energy is absorbed and dissipated by the beach, reducing erosion

Question 52

beach reprofiling pros

Answer 52

residents feel safer ecosystems behind the beach are protected looks natural

Question 53

beach reprofiling cons

Answer 53

can be expensive machines restrict beach access may look uninviting to tourists if the beach is steep and high crested

Question 54

sand dune regeneration

Answer 54

artificial creation of new dunes or restoration of existing ones results in a physical barrier between sea and land, absorbing wave energy

Question 55

sand dune regeneration pros

Answer 55

maintains a habitat often uses volunteer labour and local grass so is cheap protects the land behind popular as a walking or picnic area

Question 56

sand dune regeneration cons

Answer 56

no guarantee it will last - dynamic environment has to be checked often systems must be put in place to prevent areas being trampled fenced off whilst being established - off putting

Question 57

managed retreat

Answer 57

a deliberate policy allowing the sea to erode or flood an area allows sea to indundate land and create new intertidal habitats more sustainable longterm

Question 58

medmerry sussex

Answer 58

on the stretch of the se coast most affected by flooding new embankment created with a channel behind rock armour built up intertidal area created finished in 2014, first such scheme in the UK

Question 59

managed retreat pros

Answer 59

cheaper than having to maintain hard engineering methods may take pressure off areas further down the coast and reduce the risk of flooding designed to conserve or enhance natural environment - new habitats created

Question 60

managed retreat cons

Answer 60

people are moved out and buildings are demolished - disruption and distress as communities are split up relocation makes short term costs high large areas of agricultural land are lost bird habitats affected eg cranes, bittern

Question 61

coastal management scheme lyme regis - why

Answer 61

cliffs are unstable and prone to landslides and erosion harbour is used for fishing and cliffs are important for fossil studies is a large tourist destination on the south coast

Question 62

lyme regis management strategy

Answer 62

phase 1 - 90s (60m) sea wall and promenade, cliff nailing to emergency stabilise cliffs phase 2 - 2005-7 (22m) new sea walls/promenade, wide shingle and sand beach created, extension of rock armour at the cobb phase 3 - scrapped phase 4 - 2013-5 (19.5m) 390m sea wall in front of old one lots of nailing, piling and drainage to stablilise the cliff and protect homes

Question 63

lyme regis outcomes pros

Answer 63

defences have stood up to recent stormy winters, fewer landslides harbour is better protected, benefitting boat owners and fishermen new beaches increase visitor numbers so seafront businesses can thrive

Question 64

lyme regis outcomes cons

Answer 64

more visitors so more traffic and litter have new defences spoilt the natural landscape new sea wall will interfere with coastal processes and affect neighbouring stretches of coastline - conflict elsewhere stabilisng cliffs will prevent landslips exposing important fossils