2.b - FLAM HEAD CS Flashcards
what type of coastline is the yorkshire coast?
discordant
at the southern end, there is a large chalk headland
then there are sandstones, shales and limestones.
meaning that there are bands of harder and softer rock, lending themselves to the formation of bays/headlands
significance of geology at yorkshire coast
geology will be a long term and permanent factor influencing the landscape that will determine the rate at which marine processes can occur.
how is wave energy influenced by wind at yorkshire coastline?
the winds blow from the north meaning that there is a large fetch of 1500km , as a result the waves have a high energy therefore are mostly destructive
longshore drift moves sediment from north to south
how does wind and wave energy vary on the yorkshire coast?
the winds and therefore the wave energy will vary from day to day (diurnally)
and from summer to winter (seasonally).
most days the wave energy will not be very strong and there will be relatively low levels of erosion and therefore change to the landforms, but then storms could bring very high levels of energy, causing rapid change in short periods of time, mostly the winter.
where is sediment supplied from at the Yorkshire coast?
- as sea levels rose during the last ice age, material was moved onshore (in the same manner as a barrier beach). clearly this input is historic and is no longer happening, therefore sediment being removed will not be getting replaced by this.
- erosion of chalk, sandstone, shale and limestone cliffs. this is ongoing, the rate of input depending upon geology and wave strength.
- the river Esk deposits sediment (but due to it being a heavily managed river, this is minimal).
LANDFORMS - saltburn to Flamborough head
high wave energy along a 60km long coastline in yorkshire
LANDFORMS - geology of the yorkshire coast
mainly of sandstone, shales and limestones formed during the jurassic period as well as some Carboniferous
LANDFORMS - yorkshire coast fetch
the dominant waves affecting this coastline are from the N and NW with the distance of open sea greater than 1500km
LANDFORMS - erosion rates at yorkshire coast
the rates vary along the coast from 0.8m/yr shale and chalk to 0.1m/yr
LANDFORMS - flamborough head
large chalk headland.
the cliffs have till on top, a superficial deposit left behind by glaciers during the Devensian glacial period
LANDFORMS - sediment sources at yorkshire coast
nearshore - driven onshore as sea levels rose at the end of the last glacial period
cliff erosion - sandstone and chalk, boulder clay and gravel
river esk enters at Whitby - this supplies only limited sediment
LANDFORMS - cliffs at flamborough
made of chalk, which is physically strong,
the cliffs are high 20-30m and vertical.
however the top of the cliffs (composed of till) are lowered by mass movement to an angle of about 40 degrees
LANDFORMS - cliffs at robin hood’s bay and saltburn
stepped profile due to more varied geology
steeper areas - sandstone and limestone
LANDFORMS - shore platform at robin hood’s bay
typical angle of 1 degree and maximum width of 500m
formed within the last 6000 yrs
relict feature
LANDFORMS - filey bay
eroded into weak Kimmeridge clay
more resistant limestone and chalk either side forming the headlands
LANDFORMS - beach at saltburn
it has a net increase of sediment of 9245m3 between 2008 and 2011.
a rare example along this coastline as the waves ususally erode sediment before accretion (accumulation) can take place
LANDFORMS - robin hood’s bay
eroded into lower lias shales.
with stronger bands of sandstone to the north (ness point) and south (ravenscar), forming the 2 headlands
how will the cliffs at Flamborough change over time?
lower part is strong rock with tightly bonded material
slow to erode via marine processes
cliff collapse is most likely in stormy weather
the upper half of the cliff which is weaker will see a lot more biological weathering and mass movement (slumping/slipping) more regularly
erosion here will happen more extensively in the winter compared to the summer
how will the cliffs at Robin Hood’s Bay and Saltburn change over time?
there are horizontal bedding planes here with stronger rocks interspersed by weaker rocks
the weaker rocks will be subject to more weathering and erosion therefore slumping is more common, making the angle of cliff not as steep
these will retreat more quickly than the Flamborough Head cliffs
erosion here will happen more extensively in the winter compared to the summer
how will the shore platform at Robin Hood’s Bay change over time?
probably formed over the last 600 years, but as a shore platform grows, it acts as its own breakwater
therefore waves will erode the shore notch, making the platform bigger at a slower rate
as a result, this shore platform will not be growing quickly, unless sea level rise means that the waves can reach the base of the cliffs more regularly
how will Filey Bay change over time?
the bay will be accumulating sediment during summer constructive wave periods
but will be losing sediment in winter months due to winter storms and destructive waves
a dynamic equilibrium will exist, which will keep the beach roughly the same size
how will the beach at Saltburn change over time?
it has a net increase of sediment of 9245 m3 between 2008 and 2011
it will be losing sediment in winter months due to winter storms and destructive waves
how will the green stacks pinnacle change over time?
over time, a stack will collapse to form a stump
most likely during a winter storm after years of erosion
how will the arch at selwick bay change over time?
arch will eventually collapse to form a stack
how is geology (main 2 rock types chalk/limestone and lias) and stacks/stumps (e.g. Flamborough Head/Green Stacks) interrelated?
discordant coastlines create layers of hard and soft rocks
this means that headlands stick out (harder rock).
over time, these can be eroded by high energy waves refracting and creating stacks and stumps
e.g. Green Stack at Flamborough Head or Selwick Bay?
how are wave energy and bays (e.g. Fiely Bay/Selwicks Bay) interrelated?
waves become divergent in Filey Bay
reducing wave energy
increasing deposition rates
how are headlands and bays (e.g. Fiely Bay/Selwicks Bay) interrelated?
wave energy is focused on headlands like Filey Brigg
Filey Brigg Headland absorbs destructive wave energy reaching Filey Bay (due to wave refraction. waves slow down ∴ low energy in bay ∴ deposition)
therefore there is less destructive waves = ↑ deposition = biggest bay (wave refraction)
how are cliffs (Flamborough Head/Ness point) and wave energy interrelated?
the headland at Filey brigg will act as a focal point for wave energy
which causes waves to refract
how are cliffs (Flamborough Head/Ness point) and bays (e.g. Fiely Bay/Selwicks Bay) interrelated?
cliff erosion provides main source of sediment
Lias eroding at a rate of 0.8m/y provides sediment source
how are cliffs (Flamborough Head/Ness point) and shore platforms interrelated?
shore platforms are found at the base of cliffs
robin hood’s bay
horizontal dip of rocks
shore platform protects cliffs and slows rate of erosion
how have cliffs eroded at robin hood’s bay?
cliffs at robin hood’s bay retreated over the past 6000yrs
now in equilibrium
explain how significant geology is in influencing the landforms on the Yorkshire coastline?
strongly influenced by geology
adjacent North York Moors comprise mainly sandstones, shales and limestones formed during Jurassic Period
Flamborough Head = large chalk headland. cliffs are topped with glacial till
differences in rock resistance are responsible for the varied coastal scenery, notably the high cliffs and bay/headland sequence
explain how significant wave energy is in influencing the landforms on the Yorkshire coastline?
dominant waves affecting this coastline are N and NW, with a fetch of over 1500km
most exposed parts of coast are those that are northfacing and so these recieve the highest inputs of wave energy
rates of erosion vary, partly due to these differences in wave energy inputs, but also due to variations in the resistance of the different geologies
destructive waves dominate
explain how significant sediment sources is in influencing the landforms on the Yorkshire coastline?
sediment cell 1, subcell 1D
some sediment has been driven onshore as sea levels rose at the end of the last glacial period
cliff erosion, including sandstone and chalk from the resistant rock outcrops + boulder clay deposits which yield significant amounts of gravel
only river supplies limited amount of sediment due to weirs and reinforced banks built
net ↑ in beach sediment of 9245 m3 2008-11 at Saltburn
how significant is sediment sources in influencing the landforms on the Yorkshire coastline?
would change seasonally as wave power changes
(more erosion = more sediment input)
how significant is geology in influencing the landforms on the Yorkshire coastline?
most significant!!
varying hardness creates e.g. headlands and bays which determines landform types
SCALE AFFECTS EVERYWHERE. if rock is very hard it will resist erosion irrespective of strength of wave energy
chalk has faults = arches, stacks and geos etc. erodes at 0.1m/yr whereas weak clay erodes at rate of 0.8m/yr
determines the speed of erosion
time => consistent over time
how significant is wave energy in influencing the landforms on the Yorkshire coastline?
may only be significant in winter storms
wave energy is not the same all year round
TIME = seasonal changes. more destructive waves in winter, day to day changes, wave energy is not consistent
SCALE = some places are more exposed (e.g. Filey Brigg headland) where as Filey Bay is sheltered ∴ wave energy is more constructive.
the features of flamborough head
as the cliffs retreat a noticeable notch indicates how powerful wave energy can be
vertical joints allow waves to penetrate the cliffs and together with faults these can lead to the formation of caves and geos.
wave quarrying can result from the sheer weight of the waves striking the cliffs (hydraulic pressure) or from air being trapped in faults and acting pneumatically as waves break.
wave refraction further concentrates waves on headlands allowing caves to develop progressively into arches, stacks and stumps.
subaerial (cliff face) processes like rock falls are also important here and work together with cliff foot (sea) processes to create these headland features.
at selwick’s bay there are heavily faulted sections of chalk and where there is a master fault the wave energy has opened up to form a blow hole which will eventually develop into a geo.
