coastal processes and landforms

Question 1

hydraulic action

Answer 1

-air trapped in cracks compressed by force of waves crashing against cliffs
-air trapped experiences greater force in next cycle of compression
-disloges blocks of rock from the cliff face

Question 2

what rock type is vulnerable to hydraulic action

Answer 2

-heavily jointed/fissured sedimentary rocks
-in very hard igneous rocks, may be only erosive process operating

Question 3

abraison

Answer 3

-sediment picked up is thrown against the cliff face
-chiselling away at surface
-wear down by removing small rock particles

Question 4

influence of lithology on abraison

Answer 4

-subtly loose sediment has to be available like shingle or pebbles
-softer sedimentary more vulnerable than hard igneous rocks

Question 5

influence of lithology on attrition

Answer 5

-softer rocks very rapidly reduced in size

Question 6

attrition

Answer 6

-acts on already eroded sediment
-collisions between particles chip fragments of sediment
-sediment becomes smaller and rounded

Question 7

what is a landscape (describe questions)

Answer 7

-two or more landforms

Question 8

how does a wave cut platform form

Answer 8

-sea attacks base of cliff and undercut forming a wave notch
-notch becmes larger and weight of cliff causes it to collapse
-as cliff collapses, rubble washes away by waves causing abraison and forming a wave cut platform

Question 9

steps of how a wave cut notch formed

Answer 9

-cracks at base of headland in inter tidal zone become exposed through hydraulic action
-cracks widened by weathering processes like salt crystallisation
-cracks develop into wave cut notches

Question 10

how does a cave form

Answer 10

-abraison and hydraulic action deepen notch to form caves
-bc of wave refraction, destructive waves concentrate energy on sides of headland, deepens the cave

Question 11

how do archs form

Answer 11

-wave refraction affects all 3 sides of headland and if 2 waves align, waves may cut through to form arch

Question 12

how to stacks form

Answer 12

vertical joints exposed by tall breakers associated with destructive waves, over time arch becomes unstable and collapses under own weight to form a stack

Question 13

whats swash aligned

Answer 13

-wind blowing directly onshore

Question 14

whats drift aligned

Answer 14

-wind blowing in at an angle

Question 15

what causes the waves to come back down at 90 degree

Answer 15

-friction from beach dissipates wave energy

Question 16

what is wave approach angle determined by

Answer 16

-prevailing wind

Question 17

whats traction

Answer 17

-when sediment rolls along pushed by waves and currents

Question 18

whats saltation

Answer 18

when sediment bounces either due to force of water or wind

Question 19

whats suspension

Answer 19

sediment carried in water column

Question 20

whats solution

Answer 20

dissolved material carried in water in solution

Question 21

what influences transportation

Answer 21

-currents

Question 22

whats currents

Answer 22

-flows of seawater in a particular direction driven by winds or differences in water density, salinity or temperature

Question 23

what are two depositional processes

Answer 23

-gravity settling
-flocculation
-occurs when energy of transporting water becomes too low

Question 24

whats gravity settling

Answer 24

-large sediment deposited first followed by smaller sediment

Question 25

whats flocculation

Answer 25

-small particles (like clay) clump together due to electrical or chemical attraction -become large enough to sink

Question 26

how does either swash or drift aligned longhsore drift affect bays

Answer 26

-wave refraction can cause either but typically more swash aligned

Question 27

what is a spit

Answer 27

-sand or shingle beach ridge extending beyond a turn in the coastline -at the turn longshore drift current spreads out and loses energy leading to deposition

Question 28

what is the length of a spit determined by

Answer 28

-existence of secondary currents causing erosion (flow of river or wave action)

Question 29

example of spit

Answer 29

-spurn head on the holderness coast

Question 30

whats a bayhead beach and how is it formed

Answer 30

-swash aligned feature -sediment moved into bay where beach is formed -due to wave refraction erosion concentrated at headlands and bay becomes area of deposition

Question 31

example of bayhead beach

Answer 31

-lulworth cove, dorset

Question 32

whats a tombolo

Answer 32

-sand or shingle bar that attaches coastline to an offshore island

Question 33

how do tombolos form

Answer 33

-due to wave refraction around an offshore island -creates area of calm water and deposition

Question 34

example of tombolo

Answer 34

-st ninians tombolo, shetland

Question 35

whats a barrier beach/bar

Answer 35

-sand or shingle beach connecting two areas of land with shallow water lagoon behind

Question 36

whats a cuspate foreland

Answer 36

-triangular shaped features extending out from a shoreline -growth of two spits from opposing longshore drift directions

Question 37

what do depositional landforms depend on

Answer 37

-sediment supply and direction of prevailing wind

Question 38

what does a spit consist of

Answer 38

-largely unconsolidated material

Question 39

why does river discharge prevent a spit continuing

Answer 39

-disrupts the sediment flow -causing sediment starvation (which also may be due to human interaction)

Question 40

what two things can happen if wave energy increases to a spit

Answer 40

-destructive waves either: -cause a loss of sediment, overtopping removes vegetation, destabalising so reduced size of spit -or cld bring sediment so build up a spit

Question 41

in order for a spit to form, what must be balanced

Answer 41

the dynamic equillibrium

Question 42

what do depositional landforms depend on

Answer 42

sediment supply and direction of prevailing wind