coasts Flashcards
What are the 7 properties of constructive waves
1.smaller in height-low wave height, long wavelength
2.less energy
3.weak backwash
4.little erosion, depositional
5.strong swash which pushes material up the beach
6.light moderate winds
7.low frequency
8 properties of destructive waves
1.strong backwash, undertow
2.weak swash
3.high wave height, short wavelength, larger in height
4.more energy
5.scours the beach, pulling sand and shingle down beach
6.little beach building, erosional
7.strong winds
8.high frequency
What is erosion
Wearing of rock away along the coastline-moving force causes this, destructive waves are responsible for this as they have more power,
4 types of coastal erosion
Hydraulic action, abrasion, attrition, solution
What is hydraulic action
hydraulic action=sheer power of the waves as smash against the cliff, air is trapped in cracks of rock and cause it to break apart due to compressed air creating pressure, rock is disintegrated
What is abrasion
When pebbles/sediment grind along a rock platform, over time rock becomes smooth
What is attrition
Rocks carried by sea knock against each other, become smaller and rounded
What is solution
Sea water dissolves certain types of rock eg chalk and limestone
What is the odd one out between the four types of coastal erosion
Attrition is the odd one out as it does not erode the cliff, it just erodes sediment compared to the others
What is the top of the cliff called and it’s role
Cliff face=where most of the weathering takes place
What is the bottom of the cliff called and it’s role
Almost all coastal erosion takes place at the cliff foot
What are the two types of winds that hit the uk
1.prevailing wind-south westerly, from the Caribbean, 5km fetch- creates strong winds as it blows over ocean, meaning it experiences less friction
2.arctic winds-northerly, also won’t experience as much friction
why are high energy coastlines and 5 features of them
powerful waves for much of the year, rates of erosion exceeds rate of deposition (earosional features), strongest towards the west coast of ireland, fetch is long, cliffs form, stack, stump, arches, strongest in cornwall, devon (southwest england), across atlantic ocean, lack of friction, large amount of energy built up, winds from north west
5 features of a low energy coastline
less powerful waves, coast is sheltered from large waves, rates of deposition exceeds rate of erosion (depositional features), examples include west wales coast as ireland shelters it, spits, bars (depositional)
examples of high energy coastlines
northern scotland (from arctic winds), north west scotland-the hebrides
examples of low energy coastlines
southern kent and sussex
what are discordant coastlines
bands of hard /resistant rock and soft/less resistant rock forming headlanfs and vays, layers of geology perpendicular to coastline
process of discordant coastline
1.wave cut notch forms in cliff foot
2.then erodes into a cave
3.cliff face unable to support itself therefore it moves back after rock fall
4.new cliff face forms
5.continues into wave cut platform
6.headland erodes from cave to arch to stack to stump
why are waves hitting headlands the most
as waves get closer to headland, it begins to refracr as forces of waves focused in headland due to wave refraction due to frictional drag as the waves refract around the headland
what are concordant coastlines
bands of soft/less resistant and hard/resistant rock run parallel to the coast, breaches in hard rock occur in fault lines, or weakenesses of the rock, creaves a cove from wave direction, an example is dorset coast and lulworth cove
holderness coast case study
-flamborough head made of sedimentary, hard chalk
-prevailing winds from north sea
-made of boulder clay (unconsolidated glacial deposits, not been crushed, into layers, very weak rock creates a problem)
-5 towns-birdington, hornsea, mappleton, great cowden, witherses, easington
-spurn head/point
-has the river humber estuary
-fluvial deposits-river
-holocine
-in east yorkshire, uk
-to the south there is hull
adjacent to river humber
birdington-holderness coast case study
sea wall-reflects wave energy
groynes-limits longshore drift, maintains beach
-main economy is tourism for its beach
-pier
-0 metres per year of erosion
mappleton-holderness coast case study
-stone groyne that limits longshore drift, expensive, made beach wider, the bigger the beach, the more wave energy it can absorb
-rock armour to south which prevenets cliff erosion, rip rap absorbs wave energy and reduces cliff foot erosion movement, only extends 100m south of groyne which is precise to the area protected
-sloped cliffs/regraded, less vertical, limits mass movement
easington- holderness coast case study
-gas terminal to receive north sea gas, highly protected
-riprap/rock armour absorbs wave energy and cliff foot protects
-regraded cliff
What is longshore drift
Movement of sediment along coastline
5 features of long shore drift
Direction of movement is to the right, swash and backwash, backwash is at a right angle to the beach due to gravity as there is no kinetic energy left,
What type of coastal defence can stop longshore drift
Groynes, slow and limit ld
5 coastal features formed from deposition
1.spit
2.baymouth bar
3.double spits
4.tombolo
5.cuspate foreland
What is a spit and what is its features
Extended stretch of beach material, stretching out to sea, joined to main land at one end
Salt marsh is formed, has a proximal end and distal end which is near the estuary, has longshore drift, two winds- prevailing wind, and second most dominant wind and fetch,
Hooked spit due to second most dominant wind amd fetch, estuary is where the river flows into the sea, the flow of the river/current prevents the spit extending across the estuary,
Used as a defensive site, light houses, golf course, caravan parks, very prone to flooding and coastal erosion
What is a baymouth bar and how does it form
Similar to spit, but extends to both ends, can be caused by a storm wave which picks and deposits an offshore bar on the coastline
What is a double spit and how is it formed
Two spots growing at different or opposite directions at the mouth of a harbour,
a result of two dominant wind directions, do not meet due to rivers current, for Weymouth , the Isle of Wight funnels winds
What is a tombolo and how is it formed
Where an island is linked to the mainland by a beach, forms by longshore drift, overtime beach is extended, eg Burgh island in south Devon use sea tractors
What is a cuspate foreland and how is it formed
Triangular depositional feature, Can build nuclear power stations, formed due to longshore drift, dungeness in Kent eg
what is littoral zone
wider coastal zone including adjacent land areas and the shallow parts of the sea just offshore-exposed to air at low tide and underwater high tide
4 parts of the littoral zone
- backshore= usually above influence of waves, above tide line, not covered on an average day tide
2.foreshore= intertidal surf zone, where backwash and swash take place
3.nearshore=breaker zone, breaking waves occur (when waves spill over)
4.offshore=beyond the influence of waves, open sea
what is the breakpoint par
zone of breaking waves between nearshore and offshore
3 types of tides
max spring tide/rare, high tide and low tide
what is tides
cuased by gravitational pull of moon or sun, long period waves that appear to move through ocean, water bulging into ocean,
high tide
sea surface reaches highest point
low tide
sea surface at lowest point
tidal range
difference between high and low tide
how many tides occur in a day
2 hgih and 2 low a day based on lunar day, at different times everyday-need tide map and timetable
what are spring tides
highest high tides-due to moon and sun alignment, two a month
what are neap tides
lowest low tides, two a month
problems with spring tide
when spring tides occur simultaenously as major storm systems, lead to severe problems, storm tide is pushing in land faster, 1953 storms of east anglia and holland- worst flooding since records began, 2 metres higher than predicted, storm surge, arctic winds push water southwards, funneled narrower and narrower so water height and keeps risiing, very low line/low land, therefore flooding cannot be intercepted
4 types of marine transport
1.suspension=lighter sediment suspended in water, clay particles (light)
2.traction=rolling or dragging of large grains along a river bed, pebbles
3.saltation=smaller sediment bounces along the sea bed pushed by currents
4=when weak carbonic acid in seawater dissolves and breaks down, limestone is most susceptible
What are the three types of rock and examples of them
1.sedimentary=strata-limestone, chalk, limestone, consolidated
- igneous=cooled lava-granite, basalt-95% of earths crust
3.metamorphic=changed by pressure and or heat- shale into slate, sandstone into quartzite, limestone into marble
What is the rock cycle
What is the relation between geology and location
Location of igneous and metamorphic is in upland areas/topography as it is more resistant to erosion
Resistant rock coastlines-6 characteristics
1.south west England-Cornwall
2.igneous-basalt and granite
3.sedimentary-sandstone (old red)
4.metamorphic-slate and schists
5.can withstand prevailing wing and long fetch
6.heavily consolidated sedimentary-heavily resistant
Coastal plain landscape 5 characteristics
1.eastern and southern uk
2.weaker and younger geology
3.chalk, clay, sandstone
4.deposition> erosion as it is a low energy coastline
5.coastal plain-area if low and flat relief-low lying sandy beaches
4 properties of low energy coastlines
Less powerful waves, deposition is stronger than erosion, stretches of uk coast which are chefs and spits and cuspate foreland
4 properties of high energy coastlines
Powerful waves, high erosion, erosion is stronger than deposition, Atlantic coastline, headland, cliff, wave cut platforms
