Coasts Flashcards
What is enquiry question 1?
why are coastal landscapes different and what processes causes these differences?
What is the definition of concordant coasts?
this is where bands of more resultant and less resistant rocks parallel to the coast
What are the key landforms of a concordant coast?
Dalmatian coasts- formed as a result of rise in sea level. Valleys and ridges run parallel to each other. When valleys flood ( due to sea levels rising ) the tops of the ridges remain above the sea. Looks like offshore islands.
Example: Dalmatian coasts of Croatia
Haff coasts- consists of concordant features, long spits of sands and lagoons aligned in parallel to the coast
Example: Southern shore of the Baltic sea
What is the definition of a discordant coast?
the geology alternates between bands of more resistant and less resistant rock which run at right angle to the coast
What are the key landforms of a discordant coast?
Headlands- force incoming waves to refract or bend concentrating their energy at the headlands. this increases the waves erosive power which leads to steepening of the cliff and their eventual erosion into arches
Bays- waves energy dissipates and reduces in the bay. This leads to deposition of the sediment.
What is the definition of deformation?
degree to which rock units have been deformed (tilted or folded) by tectonic activity
What is the definition of faulting?
presence of major fractures that have moved rocks from their original position
What is the definition of bedding in terms of rocks?
where rock types meet
What is a dip?
The angle in which rocks lie at an angle usually seen in deformed strata
What type of cliff profile is at a low angle with one rock layer facing the sea (usually vunrable to rock slides)?
Seaward Dip (high angle)
What type of cliff profile is vertical profile with notches reflecting strata that are more easily eroded?
Horizontal Dip
What type of cliff profile is steep profile of 70-80 degrees producing a very stable cliff with reduced rock fall?
Landward Dip
What type of cliff profile may exceed 90 degrees producing areas of overhanging rock (very vunrable to rock fall)
Seaward Dip (low angle)
What is the erosion rate of sedimentary rocks?
0.5 - 10 cm per year
What is the erosion rate of metamorphic rocks?
0.1 - 0.3 cm per year
What is the erosion rate of igneous rocks?
<0.1 cm per year
What are examples of sedimentary rock?
chalk, clay, conglomerate
What are examples of metamorphic rock?
Marble, slate, Gneiss
What are examples of igneous rocks?
Basalt, Granite, Gabbro
What is a psammoseres?
Sand dunes
What is a haloseres?
Salt marshes
What rock type and what are the characteristics of gabbro?
igneous
course grained and dark coloured
What rock type and what are the characteristics of conglomerate?
Sedimentary
clasts are well rounded and vary in size
What rock type and what are the characteristics of Gneiss?
Metamorphic
distinctive banding caused by segregation of mineral grains into layers often alternating between dark and light
What is the definition of a high energy environment?
where destructive storm waves breaking on shingle beaches are most typical
What is the definition of a low energy environment?
where constructive swell waves breaking upon sandy beaches are most typical
What two categories did Valentino use for coasts?
advancing- where marine deposition or the uplift is dominant
Retreating- where marine erosion or the submergence of land is more significant
What is the definition of marine erosion?
wearing away of the land surface and removal of materials by river and seawater, ice and wind
What is the definition of marine deposition?
Deposition occurs when energy levels decrease in environments such as bays and estuaries. Where deposition occurs on the inside of a spit a salt marsh can form
What does the littoral zone consist of?
coast
backshore
foreshore
nearshore
offshore
What four types of coast line are formed by the littoral zone?
rocky- resistant rock with high energy environments also destructive waves
sandy- low relief areas, low energy environments with more deposition than erosion
estuarine- salt marshes and mud flats river mounds with more deposition than erosion
What is short term classification?
energy inputs (high and low energy coastlines)
sediment inputs (deposition and erosion rates)
advancing and retreating (happens due to erosion and deposition rates)
what are the characteristics of a coastal plain?
flat land, low relief, often containing wetlands and salt marshes, low energy environments, high deposition
Mostly south-east UK
What are the characteristics of a rocky coast?
Cliffs that vary in height, high resistant rock, low relief, little deposition with high erosion
Mostly north-west UK
What are faults?
major fractures caused by tectonic processes
What are joints?
fractures created by rocks being moved
What are fissures?
more open than fractures
What is folding?
bends in rock due to sedimentary rock layering
What is anticline and syncline?
anticline-top of curve
syncline-bottom of curve
What is enquiry question 2?
how do characteristics of coastal landforms contribute to coastal landscapes?
What causes waves to be stronger and higher?
strength of wind
water depth
duration of wind blowing
distance of sea travelled (fetch)
What is an example of a long fetch?
Cornwall (longest prevailing wind of 4000km)
What are the characteristics of a constructive wave?
long wavelength
low surging waves
strong swash
weak backwash
beach gain
What are the characteristics of a destructive wave?
short wavelength
high plunge waves
weak swash
strong backwash
beach loss
What are the four erosional processes?
abrasion
hydraulic action
attrition
solution
what is marine processes?
action of waves
define erosion
wearing away of land surface and removal of material by river
what is abrasion
when waves advance they pick up sand and pebbles from sea bed and throw them at cliff face
what is hydraulic action
when wave advances air can become trapped and compressed in faults then the wave retreats air expands. This continuous process weakens the faults
what is attrition
gradual wearing down of rock particles by impacts and abrasion as [pieces of rock are moved by waves and tides
what is solution
when a cliff is formed by alkaline rock or cement bonds the rock particles together, solution by weak acids in salt water dissolve them eroding them down
define geomorphic
relates to the formation and shaping of landforms and landscapes by natural processes such as weathering, mass movement transportation and erosion
define weathering
breakdown or disintegration of rock in situ (original place) as a process it leads to the transfer (flow) of material
define mass movement
downhill movement of material under the influence of gravity
define marine process
includes erosion, transportation and deposition. Caused by power of wind which transfers energy to waves
what is an example of bay beaches
dorset coast
what is an example of bay bars
looe cornwall
what is an example of barrier beaches
start bay, Devon
what is an example of spits
Orford Ness Sufolk
what is an example of recurved spits
Hurst castle spit Hampshire
what is an example of cuspate forelands
Carolina USA
what is an example of tombolo’s
loch Eriboll Scotland
what is an example of a sediment cell
Portland bill
How many sediment cells are there in England and Wales?
11
What three components make up a sediment cell?
sinks, transfers and sources
What isa sediment cell
it is a closed system which is in dynamic equilibrium meaning no sediment is transferred between each cell
What are sources
places where sediment generated
What are transfer zones
place where sediment moving alongshore
What are sinks
locations where dominant process is deposition
What are examples of sources
erosion on cliff
onshore currents supply sediment to shore
land sediment eroded by rivers
wind-blown sediment from land
subaerial processes such as weathering and mass movement
shells and remains of marine organisms
What are examples of transfers
longshore drift
wave transport through swash and backwash
tides moving sediment in and out
currents- localised or large scale
wind alongshore and off shore
What are examples of sinks
backshore depositional landforms
foreshore depositional landforms
nearshore depositional landforms
offshore sediment deposition to deep offshore waters
What is negative feedback
maintains balance e.g. wave erosion causes rock fall which protects the base from further erosion
What is positive feedback?
changes the balance until a new equilibrium is reached e.g. sand dunes are damaged during storm causing ‘blow out’ (depressions/hollows) allowing wind to move sand away , preventing marram grass from re-growing = more erosion
What is mass movement?
movement of material downslope as result of gravity can be slow or fast. Water commonly acts as lubricant
What is soil creep?
slow downhill movement of soil and debris under the influence of gravity
What are mudflows?
fast movement of mass of water saturated soil, rock and debris that move downhill due to gravity.
Often occur after lots of heavy rainfall causing excessive friction between particles
What is solifluction?
is the slow downslope movement of water logged soil and sediment caused by upper layer thawing during summer while permafrost still remains
What is rock fall and talus slopes?
larger bits of rock fall down the cliff face, usually due to freeze thaw weathering
this creates talus slope, when the rock falls almost vertically, down the side of the cliff face
The coastline loses in shape and becomes more like a slope
What are translational slides?
a translational or planar landslides is downslope movement of material that occurs along a distinctive planar surface of weakness such as a fault, joint or bedding plane
What is rotational slumping?
occurs when a slump block, composed of sediment or rock, slides along a concave-upward slip surface with rotation around the axis parallel to the slope
What are plant roots?
a seed from a plant lands in crack of a rock and as it grows the roots grow into the crack causes it to widen
this is a mechanical process that creates more surface area for other weathering processes to act upon
What is rock boring?
rock boring acts as a catalyst within subaerial processes by initiating and enhancing the breakdown of rock material through biological means
Molluscs and sponges bore into cliffs and rocks along shorelines, weakening them and contributing to erosion
What are seaweeds acids?
kelps contains pockets of sulphuric acids, when cells break, sulphuric acids attacks nearby rocks minerals like calcium carbonate, this leads to a chemical reaction similar to carbonation, increasing ocean acidity
How does seaweed acids affect the landscape?
increases the oceans acidity means that erosion is quicker because the acid in water attacks the rocks
The increase in erosion makes the coastline more rocky
What is freeze thaw weathering ?
is the continuous ongoing expansion of rock faults.
What is salt crystallisation?
disintegration of rocks when saline solution seeps into cracks or faults of rocks then evaporates leaving salt crystals
What is oxidation?
chemical process of oxidation is the reaction of a substance with oxygen
What is hydrolysis?
affects the coast by causing weathering especially on softer rock types. Occurs when a mineral within a rock reacts with water to produce a new substance which can usually be eroded faster.
