Waves Flashcards
Spot height
height of land above sea level
What type of rock forms most UK mountains
hard resistant rocks such as granite and slate form the most dramatic mountains in the Uk
Chunks and cracks in limestone
chunks- clints
cracks- grykes
Types of weathering
mechanical:
- freeze thaw
- salt mechanical
Biological:
- all the plant ones
Chemical:
- dissolving rocks due to the slight acidity of water
Uk relief
Scotland and higher elevation+ metamorphic -from the lower palaeozoic (metamorphic rock is impermeable so water sits on top)
Lowland areas more commonly further south are made of chalk and clay which are more porous letting water pass through
How are waves formed
the distance and waves has been blowing and the strength of the wind is called the fetch. the larger the fetch the bigger the wave. it travels in a circular motion towards the shore but as the seabed is less shallow the top speeds up causing the wave to break
Uk’s prevailing wind direction
south west (from the atlantic)- large fetch
Swash and Backwash
Swash- water traveling onto shore (if stronger constructive)
Backwash- water travelling offshore(if stronger destructive)
Constructive Vs destructive waves
c- not tall, less frequent (6-8 a minute) formed by storms often 100s of Kms away
d- 10-14 waves a minute, tall , made by strong winds, have a large fetch
Weathering Vs erosion
weathering is in situ whereas Erosion moves mass
mass movement
the downward movement or sliding of materials under the influence of gravity- can deliver loose materials to beaches to be eroded
Landslide
large blocks of rock moving along a shear surface often lubricated by water
Slumping
rapid mass movement involving huge sections of a cliff moving down-slope alongs a saturated curved segment(often due yo waves undercutting the cliff)
rockfall
fragments of rocks break off a cliff face due to freeze thaw weathering
mudflow
saturated soil moves down a slope
4 different coastal erosion processes
abrasion- throwing sediment at cliff face
hydraulic action- forcing high pressure water into small cracks which expand to create cave
Solution- carbonic acid of water dissolving cliff face
Attrition- rocks hitting each other to become smooth
4 erosion processes that occur in rivers
Traction- large pebbles rolling across river bed
saltation- pebbles pouncing as they are too heavy to be suspended
suspension- particles carried within the water
solution- dissolving particles
longshore drift
when waves approach a coast at an angle they move sediment diagonally across as the coast. because of gravity however the backwashcarries material back down the beach at right angles.
coastal deposition
when the force of a wave is refracted/lost the wave cannot carrie the sediment further hence it is deposited
Concordant vs discordant coastlines
concordant means the same type of rock is found all along the coast which can cause coves and lagoons to form
discordant coastlines are where the rocks alternate between hard and soft rock forming headlands and bays
wave cut platform
- The sea attacks the base of the cliff between the high and low water mark.
- A wave-cut notch
is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide. - As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
- The backwash carries away the eroded material, leaving a wave-cut platform.
- The process repeats. The cliff continues to retreat.
erosion chain
crack(hydraulic action) →cave(abrasion)→arch(widens) →stack→stump
ecosystems formed due to deposition
mud flats and marshes are found behind spits where there is little flow of water
definition of a beach
an accumulation of material transported and deposited by the sea ( can be made from- sand(often found in sheltered bays), pebbles(larger fetch, high energy waves making it steeper), coral, shell, stones)
deposition landforms
Spit- (e.g. Dawlish Warren spit Devon)- longshore drift- curve due to wind and have mudflat at the back
Bar- a spit formed from one headland to another(Slapton Sands- Devon)
Tombolo- a spit connecting an offshore island with the mainland (Isle of portland- Dorset)
Types of Dunes
embryo dunes
yellow dunes
grey dunes
mature dunes/ woodlands
embryo dunes
are quite fragile and are formed by saltation hitting and obstacle and are a host to salt resistant pioneer plants often having characteristics such as waxy leaves and plants being more scattered/lower-growing plants:
- sea rocket
- salt wort
yellow dunes
have been established for 30-40 years and are the first main ridge that reduce winds. Plants residing on yellow dunes are often salt intolerant and thrive being covered in soil e.g. maram grass
grey dunes
are host to more plants due to greater protection provided due to less salt water having a more grey soil with many planta coexisting with penial plants that last more than 2 years such as grey lichen and heather