Coasts: Landforms

Question 1

Wave-Cut Notch and Platform

Answer 1

1) as waves break against the foot of a cliff, wave energy is concentrated close to the hight tide line
2) marine erosional processes undercut the cliff, creating a wave-cut notch
3) as the wave-cut notch gets bigger, the cliff becomes more unstable and eventually collapses
4) as these erosional processes repeats, the cliff retreats - leaving behind a wave-cut platform

Question 2

Caves, Arches, Stacks and Stumps

Answer 2

1) existing weaknesses are exploited by marine erosional processes
2) as waves continue to erode the crack, a cave is formed
3) as erosion occurs both sides of the cave and more upwards erosion occurs, the cave erodes through the headland to form an arch
4) as the top of the arch becomes increasingly unstable due to sub-aerial processes, it collapses - leaving behind a stack
5) the stack is undercut at the base until it collapse and becomes a stump

Question 3

Geos

Answer 3

1) joints in sedimentary rocks made up of bedding planes are eroded by marine erosional processes
2) overtime, erosion causes crack to grow into a cave
3) when erosion excavates enough material along a joint or bedding plane, a geo (a steep sided indent) is formed

Question 4

Blowhole

Answer 4

1) joints in sedimentary rocks made up of bedding planes are eroded by marine erosional processes
2) overtime, erosion causes crack to grow into a cave
3) sub-aerial processes weaken joints in cave roof and when waves enter the cave, the compressed air and water are forced up through the vertical shaft, causing erosion
4) overtime, cave connects to surface above cliff, forming a blowhole

Question 5

Headlands and Bays

Answer 5

1) bands of soft rock are weaker and less resistant to erosion, so erode at a much faster rate - forming bays
2) bands of hard rock are more resistant to erosional processes, so erode at a much slower rate, causing them to protrude into the ocean - forming headlands
3) wave refraction concentrates wave energy onto the protruding headland, whilst the sheltered bay becomes an area of deposition

Question 6

Coves

Answer 6

1) pre-existing weakness in hard rock layer is exploited by marine erosional processes
2) hard rock is eroded through, and soft rock is now exposed to wave energy and erosional processes
3) soft rock erodes at much faster rate, and wave refraction concentrates wave energy onto soft rock - leading to much greater rate of erosion
4) erosion reaches layer of hard rock, which slows down the rate of erosion - creating a curve shape

Question 7

Tombolo

Answer 7

1) on drift-aligned coasts, wave refraction occurs on both sides of the island
2) wave fronts collide, producing a zone of still calm water where deposition occurs
3) sediment accumulates, connecting the island and the mainland

Question 8

Cuspate Foreland

Answer 8

1) longshore drift currents from opposing directions converge at the boundary of two sediment cells
2) sediment is deposited out into the sea by both currents, creating a triangular shaped area of depositional material

Question 9

Offshore Bar

Answer 9

1) sediment eroded by destructive waves is carried seawards by backwash
2) sediment is deposited at the boundary of offshore and nearshore zones, due to gravity settling

Question 10

Spits

Answer 10

1) sediment is carried by longshore drift
2) changes in coastline shape causes deposition of sediment
3) overtime, level of sand deposited will build-up until it is above sea level
4) secondary wind changes wave direction, causing them to create a curved or hooked end

Question 11

Beaches

Answer 11

1) constructive waves deposit sediment on foreshore
2) sediment accumulates to form beach

Question 12

Bayhead Beaches

Answer 12

1) on swash-aligned coasts, waves break at 90º to shoreline, concentrating erosion on headlands, whilst bays become an area of deposition
2) constructive waves deposit sediment on foreshore
3) sediment accumulates to form beach

Question 13

Barrier Beach/Bar

Answer 13

1) sediment is carried by longshore drift
2) changes in coastline shape causes deposition of sediment
3) overtime, level of sand deposited will build-up until it is above sea level - forming a spit
4) spit grows so long that it extends across a bay, closing it off

Question 14

Psammoseres

Answer 14

1) deposition occurs around obstacles, forming an embryo dune - this is stabilised by pioneer species (sand couch and lyme grass), which allow for the start of soil formation through decay
2) as more sand is deposited, larger sand dunes (fore dunes and yellow dunes) are formed. here, a greater variety of xerophytes can grow (including marram grass), which help to stabilise the dune
3) rooting vegetation adds organic matter to the sand, creating hummus. this makes it more fertile, so a greater number of species can colonise the grey dune
4) wind can form depression in the sand, called dune slacks
5) mature dunes form, where the climax community grows