landscapes in the UK Flashcards
how is rock broken down?
by mechanical and chemical weathering
what is mechanical weathering?
the breakdown of rock without changing its chemical composition
give an example of mechanical weathering
freeze-thaw weathering
explain what happens in freeze-thaw weathering
water enters cracks in rocks then freezes, this expands and puts pressure on the rock .when the water thaws it contacts wich realizes pressure. this is repeated and widens the cracks
what is chemical weathering?
the breakdown of rock by changing its chemical composition
what is mass movement?
the shifting of rocks down a slope
what is a scarp
a steep cut in the side of a slope
what are the two types of waves?
constructive and destructive
the greater the fetch of a wave the …
..more powerful the wave
when waves erode the coast what are they called?
destructive waves
what wave has a high frequency, and is high and steep?
destructive waves
what type of waves deposit material?
constructive waves
what is a destructive wave backwash like?
the backwash is more powerful than swash so the material is removed
what is constructive waves backwash like?
swash is more powerful than backwash so the material is deposited
what wave is low frequency and is low and long?
constructive waves
what three types of erosion are used to wear away coasts?
hydraulic, abrasion, and attrition
how does hydraulic power work?
waves crash against rock and compress the air in the cracks, this puts pressure on the rock .repeted compression widens the cracks and causes bits of rock to break off.
how does abrasion work?
eroded particles in the water scrape and rub against the rock, removing small pieces
how does attrition work?
eroded particles in the water collide, break into smaller pieces and become more rounded
what is a trick to distinguish the waves?
destructive waves destroy and constructive waves create beaches
when does deposition occur?
when water carrying sediment loses energy and slows down
what does prevailing mean?
most common
what are the two types of coastline?
concordant and discordant
what are discordant coastlines made up of?
alternating bands of hard and soft rock at right angles to the coast
what are concordant coastlines made up of?
alternating bands of soft and hard rock parallel to the coast
when a Headland and bays formed?
where there are alternating bands of resistant and less resistant rock along the coast, less persistent rock is eroded faster forming a bay, the resistant rock sticks out forming a Headland
what is Headland eroded to form?
caves, arches, and stacks
give two case studies of headlands
Durdle Door in Dorset and old Harry in Dorset
how is a cave formed?
waves crash into the Headland in and large the cracks so repeated arrangement causes a cave form
how is an arch formed?
continued erosion deepens the cave into a breakthrough the headlamp to form an arch
how is a stack formed?
erosion continues to wear away the rock supporting the arch until it eventually collapses
what happens when waves erode Cliffs?
wave-cut platforms are formed
how are beaches formed?
through deposition
where do spits form?
at sharp bends in the coastline
how are sand dunes formed?
when to sand deposited by longshore drift is moved up the Beach by wind
name two types of dunes
embryo dune and mature dune
how is a bar formed?
when is spit joins two heads together
what does a spit look like on a map?
they are shown by a beat that carries on out to see but is still attached to the land at one end
how are wave-cut platforms shown on a map?
best known as bumpy edges along the coast
what is the Dorset coast made up of?
bands of hard and soft rock like limestone and clay
what is Durdle Door an example of?
an arch
what is the tombolo?
a type of bar
what are the two types of coastal defences?
hard and soft engineering
what is hard engineering?
man-made structures built to control the flow of the sea and reduce flooding and erosion
what is soft engineering?
scheme setup using knowledge of the sea and its Processes to reduce the effects of flooding and erosion
name four methods of hard engineering
the sea wall, gabions, rock armour and groynes
name two methods of soft engineering
beach nourishment and dune regeneration
what is a sea wall?
a wall made out of hard material like concrete that reflects waves back to the sea
what are gabions?
a wall of wire cages filled with rocks usually built at the front of Cliffs
what is rock armour?
boulders that are piled up along the coast
what are groynes?
wooden or stone fences that are built at right angles to the coast they trapped material transported by longshore drift
what are some benefits of a sea wall?
it prevents erosion of the coast and it also acts as a barrier to prevent flooding
what are some benefits of gabions?
they absorb wave energy and reduce erosion they are cheap and easy to build
what are some benefits of rock armour?
is absorbs wave energy, reduces erosion and flooding and it’s cheap
what are some benefits of groynes?
they create why do beaches with slow waves and there cheap
what are some disadvantages of seawalls?
they’re expensive to build a matane
what are some disadvantages of gabions?
the ugly to look at and the wire cages can corrode over time
what are some disadvantages of rock armour?
folders can be moved around by strong waves so they need to be replaced
what are some disadvantages of groynes?
they starve beaches further down the coast and make them narrower
what is beach nourishment?
sand from elsewhere that added to the upper part of beaches
what is dune regeneration?
creating or restoring sand dunes by nourishment or by plant vegetation to stabilise the sand
what are some benefits of beach nourishment?
it creates wider beaches which gives greater protection from flooding and erosion
what are some benefits of Dune regeneration?
stabilisation is cheap
what are some disadvantages of beach nourishment?
it’s very expensive and has to be repeated
what are some disadvantages of Dune regeneration?
protection is limited to a small area and nourishment is very expensive
what is managed retreat?
removing current defences and allowing the sea to flood the land behind basically doing nothing
overtime what will happen to the land if it’s managed retreat?
the land will become a marshland which then protects the land behind it from flooding
what are the benefits of managed retreat?
is a cheap and easy strategy that doesn’t need maintaining
what are some disadvantages of managed retreat?
it causes conflicts e.g. flooding Farmland affect the livelihood of farmers
what’s the problem in Lyme Regis?
the cliffs need protection from erosion
why are Cliffs eroding in Lyme Regis?
powerful ways from the Southwest erode sea Cliffs causing them to collapse
what’s the population of Lyme Regis?
around 3600
what does the local economy in Lyme Regis depend on?
tourism
how many phases were there for the scheme to provide long-term protection in Lyme Regis in 1990?
four
what did phase 1 in the Lyme Regis scheme include?
building new rock armour
what is Phase 2 in the Lyme Regis scheme include
sand beaches replenished and stabilized rock armour was extended and drainage systems were improved
what did phase three in the Lyme Regis scheme include
it was meant to prevent landslides in the west of Lyme Regis but was never carried out
what did phase four in the Lyme Regis scheme include?
included 319 m of cereal and rock armour and protect roads in the town this cost 19.5 million
What is solution?
Minerals dissolve in water and are carried along
What is suspension?
Sediment is carried along in the flow of the water
What is salutation?
Pebbles that bounce along the sea or river bed
What is traction?
Boulders that roll along a sea or river bed by the force of the flowing water
Define a rock fall
The rapid free fall of rock from a steep cliff face becase of gravity
What is peak discharge?
The discharge in a period of time
What is lag time?
The decay between peak rainfall and peak discharge
What is rising limb?
The increase in the river discharge
What happens in the middle course of the river?
The gradient gets gentler so the water has less energy and moves slower
How does a waterfall form?
River flows over alternative types of rock, river erodes soft rock faster creating a step, hydrolic action and abrasion form a plunge pool hard rock Is undercut
What happens in the upper course of a river?
River flows over steep gradient, lots of energy so it erodes the river bed vertically
What happens in the lower course of a river?
River widens, becomes flatter, material is deposited
