coasts general Flashcards
what is a sediment cell
nearshore closed systems that are self contained- seperated by significant disruptions in the coastline
how many sediment cells in england
11
what inputs of sediment are there
wind erosion rivers
outputs of sediment cells
long shored rift or offshore deopsition
whats a positive sediment budget cell
more sediment in than out
characteristics of constructive waves
5 things
low wave height long wave length strong swash weak backwash depositional
what happens to profile of beach for constructive waves
starts out gentle but becomes steeper over time
destructive wave characterstics
high wave height short wavelength erosional weak swash strong backwash
becah profile for destructive waves
steep sea bed and then waves hollow out beach
example of high energy coast
holderness coastline
characteristics of high energy coast
strong winds
long fetch
erosional landform
steep offshore
characteristics of low energy coast
short fetch
little wind
gentle offshore
depositional
example of low energy coast line
severn estuary
how is wind created
air moving from areas of high pressure to areas of low presssure
what is wave energy affected by
3things
wind strength
fetch
wind duration
how does wave form
wind blows across water surface - friction causes ripples and then waves
what happens when waves approach beach
water approaches beach- shallow water slows down bottoms of the wave causing circular orbit to become elliptical = horizontal movement as wave breaks onto beach
what are tides
rise and fall of water caused by gravitational pull by sun and moon
what happens when sun and moon are alligned
spring tide
whats a current
general flow of water in one direction
whats weathering
break down of roack due to exposure in the atmosphere in situ
examples of weathering
mechanical
biological
chemical
what is chemical weathing
Chemical weathering is when the molecular structure of rocks and soils are changed, therefore becoming weaker and eroding away.
what is mechanical weathing
Mechanical weathering is the breakdown of rock without changing its chemical composition.
what is biological weathering
Biological weathering is the weakening and wearing away of rock by plants, animals and microbes.
examples of biologial weathering
roots from plants
examples of mechanical weathering
freeze thaw weathering
salt crystalisation
examples of chemical weathering
acid rain rusting
what is erosion
wearing away of rock on coastline
factors that affect erosion
7 things
wave steepness breaking point of wave slope of sea bed shape of coast sediment supply rock type of coastlne width of beach
what is a beach cusps
temporary feature that are semi circular depressions that channels swash into centre of hollow with strong back wash deepening hollows
whats a rip current
strong localised underwater current, build up of water at top of beach due to consistent plunging waves forcing backwahs underwater
whats a berm
smaller ridges that form at high tide mark form deposition at top of swash
storm beach
strong swash in storm picks up material and deposits it higher up
ridges and runnels
spreading out of waves energy energy over a large wide shallow beach
factors that affect beach profile
wave type
particle size
wave energy
where do spits occur
occur at changes in coastlne direction where theres LSD
what are spits
narrow accumulations of sand with one end attached to the mainland and other end extending out to sea
whats at the lee of the spit
heavy material
what cuases hooks
changes in wind direction - secondary winds
whats a bar
spit extends across bay to join two headlands - lagoon created
barrier island similar to offhsore bar
off shore deposition parallel to the coastline with tips and ridges exposed
whats a tombolo
spit extends from mainland to island by LSD
island shelters and protects beach
how is sand moved usually
by saltation
what is saltation affected by
wind speed
grain size
and dampness
what do sand dunes need
supply of sand gentle beach profile large tidal range net deposition prevailing on shore winds vegetation and obstacles to limit movement
what are the seral stages
embryo - fore - yellow - grey - mature (woodland)
what is plant succesion
plant development with time and direction
what pioneer species are there
sea rocket and couch grass
why are the pioneer species suitable
they can cope with very dry salty exposed conditions
what is typical species found at fore dunes and how are they adapted
marram grass with long roots to seek water
how do conditions change from embryo to mature dune
salinity decreases nutrients increase shelter increases organic content increases freshwater increases age increases
