COASTS Flashcards
extent of coastal zone area
60km onshore
370km offshore
coastal environment
where sea interacts with the and, shaping and influencing it by natural and human elements eg. through tides
discordant coastline
rock bands of differential resistance perpendicular to coastline
eg discordant coastline
swanage bay
sediment sources
- offshore marine deposits
- materials from mass movements
- wind-blown deposits
- artificial beach nourishment
sediment cell
a closed system, usually bound by headlands, in which sediment is trapped and transported around
swash-alligned beach
swash is 90 degrees to coastline - hardly any sideways movement of sediment up/down beach (minimal longshore drift)
drift-aligned beach
orientated obliquely to crests of prevailing waves - controlled by longshore drift with features eg. spits, bars, tombolos
recurved spit
made from a series of spits - several recurved edges on landward side
cusps
semicircular depressions occurring on swash aligned coastline - channel swash towards middle of embankment creating strong backwash down middle (therefore erosion)
runnel
a channel which collects water and slowly flows back to the sea
ridge
elevated area between runnels
berms
all ridges before storm beach
conditions for spits to occur
- abundant material available
- coastline irregular due ro geographical variation
- estuaries / major rivers
tombolo
ridge of material linking island to mainland
cuspate forelands
shingle ridges deposited in a triangle shape - result of 2 spits joining or combined effect of 2 distinct sets of storm waves
offshore bar formation
coarse sand/shingle - develop offshore due to gently shelving sea bed - waves feel bottom far offshore, causing a disturbance in the water - leading to deposition , forming a bar BELOW sea level
barrier beach formation
natural sandy breakwaters which form parallel to a flat coastline
conditions needed for barrier beach formation
- gently sloping, low-lying coast, unprotected by cliff
- faces the ocean
- rising sea levels = break over dunes, creating lagoon behind ridge
- waves wash sand inland from island, leading to creating of new islands
methods used to slow dune migration
- planting of grasses/vegetation - eg. marram grass - with long root systems which bind sand together
- erecting brushwood fences to reduce sand movement
- planting conifers which can stand saline environment + poor soils
storm beach
biggest boulders thrown to back of beach during storm activity at highest fo spring tides
bar formation
if a spit joins 2 headlands across a bay
eustatic sea level change
when sea level increases due to change In volume of ocean basin or volume of water (global)
isostatic sea level change
change in sea level caused by rise or fall of the land (local)
wave height
distance between wave trough and crest
wave length
length of wave from trough to trough
wave frequency
number of waves passing a certain point per minute
wave crest
point of maximum height of a wave
wave through
lowest point of a wave
fetch
the distance of open water a wave travels over
swash
the constructive movement of a wave up a beach
backwash
the destructive movement of a wave down the beach, back out to sea after breaking on the shore
constructive wave
wave with a long wavelength, low frequency, low height, a weak backwash and a strong swash, which results in the deposition of sediment
destructive wave
a wave with a short wavelength, high frequency and height, strong backwash and weak swash which results in the erosion of sediment
wave refraction
when waves hit a headland, slowing down and and causing the waves on either side to bend towards the slowest point of movement - resulting in erosion of headlands
