1.1.6 - Processes of coastal transport and deposition and the characteristics and the formation of associated landforms and landscapes Flashcards
Outline each of the 4 transportations
Solution - Minerals from the rocks are dissolved in the water
Suspension - The smallest clay-sized particles are easily carried
by the stream
Saltation - Larger particles that bounce along the bottom of the riverbed
Traction - The largest material is dragged along the bed of the river
What factors may affect sediment transportation?
Weak currents will only transport sand-sized particles. Only the
strongest currents can move pebbles by saltation.
Overall, sand particles are easiest to transport at relatively low
speeds, whereas larger gravels and pebbles require higher speed
currents. Different transport speeds mean that sediment is better
sorted over time, through the progressive differential transport of
grains of different sizes. This is referring to sediment sorting.
vertical sediment sorting - solution,suspension, saltation and traction last deposited
Describe the process of longshore drift.
waves approach the beach at an angle
material moved up the beach at an angle in swash movement
material carried directly down the beach in a backwash under gravity movement
sediment is then transported along the beach
Describe the two types of coastlines associated
with longshore drift?
swash alligned coasts - Where waves break parallel to the shore. Swash and backwash movements move material up and down the beach with little longshore drift - winds not coming in at an angle straight wind
drift alligned coasts- Where waves arrive at an oblique angle and the backwash runs perpendicular to the beach. Therefore considerable longshore drift will occur - widns come at angle e.g north east south west
Explain how deposition occurs in low energy
environments.
Deposition takes place when the velocity
of the water (or wind) falls below a critical
value for a particular size of particle and
can no longer be transported (Stokes Law).
In low-energy environments, such as river
estuaries, the very smallest clay particles
will eventually drop to the sea bed to form
mudflats
Some of this sediment may be carried
offshore to underwater sandbanks.
Explain how deposition occurs in high energy
environments.
In high-energy environments, such as…,
clay and sand will be easily transported
away leaving behind the larger pebbles to
form the characteristic shingle beaches.
What is meant by flocculation and how does it
contribute towards the process of deposition?
In low-energy environments, such as river estuaries, the very smallest clay particles will eventually drop to the sea bed to form mudflats. They do this by a depositional process called flocculation. Flocculation is important for very small particles, such as clay, which are so small they remain suspended in water. Clay
particles clump together due to electrical or chemical attraction and become large enough to sink. Where clay particles aggregate together they form flocs.
what is the process of flucution ?
suspended material - flocuation - deposition in a flow direction
What is meant by sediment sorting?
Rivers and oceans carry sediment and deposit them on the
basis of density and size and shape
what is lateral sediment sorting ?
In beach situations the energy of the waves causes
different deposition, with the largest rocks thrown
above the high water mark
boulders cobbles pebbles gravel sand silt clay
what happens in a high energy coastline and how does it cuase lateral sediment sorting ?
in high energy beach situations the energy of the waves causes different deposition with the largest rock thrown above the high water mark
this creates lateral sediment sorting where large rocks are at the top of the sea amd the smaller rocks are deposited closer to the sea
why is sediment sorting important to the coastline ?
Sediment deposition is an extremely important part of the overall coastal system specifically, the sediment cell.
Areas of deposition – beaches, spits, mudflats, sand dunes – are all sediment stores or‘sinks’.
While some sediment sinks may be considered to be outputs they can also act as important inputs to the coastal system.
e.g offshore sediment deposits have been driven onto the south coast of England by rising sea levels following the end of the last glacial period.
Describe how spits are formed. Draw an
annotated diagram.
swash moves diagonally across the coastline
and the backwash moves back into the sea
this means th small sand particles move slong the coastline and build up on one side
if a river estuarine flowing across the sea
longshore drift pushing the sand near it , the sand gets trapped along the river and ocean
a build up of sand forms at the mouth of the estuary this is where the spit is formed
if rthe prevailing wind change would curve
behinf the spit a salt marsh would form creating a new habitat overtime this would become a land
give e.g of spits
hurst spit in hampshire south coast of england
golden cape croatia
Describe how tombolos are formed. Draw an
annotated diagram
prevailing wind direction
direction of a longshore drift
change in shape of headland resulting in the formation of a spit
spits grown out from the mainland and joined to an island creatign a tombolo
tourists like but can get covered by high tid e- snager
tombolo - spit that connects the mainland to an island
