Coast Flashcards
what are the two types of waves?
Destructive
constructive
factors influencing wave strength
fetch
wind duration
wind speed
What is the wave height?
difference between a peak and trough
what is a fetch?
how far the wave has travelled
What is the wave length?
Difference between 2 peaks or 2 troughs.
CONSTRUCTIVE WAVE
height, length, break,
low
long
spill
CONSTRUCTIVE WAVE
swash, backwash, sediment
powerful swash
weak backwash
gains sediment - extend beach
DESTRUCTIVE WAVE
height, length, break
high
close
destroy/plunge
DESTRUCTIVE WAVE
swash, backwash, sediment
Weak swash
strong backwash
loose sediment - destroy beach
What is weathering?
weakening of material, while it remains in its og location.
What is mechanical weathering?
explain the process
freeze thaw weathering
a crack in a rock fills up with water
water freezes expands and cracks the rock a bit more
process continues until the rocks splits in half
what are the 3 types of weathering?
mechanical weathering
biological weathering
chemical weathering
What is chemical weathering?
the breakdown of rocks because of the interaction with air, water or acid
What is mass movement?
downhill movement of weathered material under the force of gravity.
What is biological weathering?
plants and animals weaken cliffs.
by burrowing
plant roots
4 types of mass movement
rock fall
landslide
mudflow
slumping (rotational slip)
What is a rockfall?
a type of weathering causing a section of rock to fall of a 90° cliff
What is a landslide?
what is it caused by..
section of rock that break away and slides down a slope.
caused by heavy rain or earthquakes
What is a mudflow?
what is it caused by..
Saturated soil that breaks away and slides down a slope.
caused by heavy rain and earthquakes
What is slumping/ rotational slip?
Saturated soil slumps down a curved surface
What is erosion?
The wearing away of material moving its location.
what are the 4 types of erosion?
hydraulic action
solution
abrasion
attrition
What is hydraulic action?
force of destructive wave hitting cliff causing it to break.
What is abrasion?
pebbles grind against rock - sandpaper effect
What is attrition?
collision of rocks causing them to break down.
What is solution (erosion)?
give an example
water dissolves certain types of rocks.
e.g calcium carbonate is dissolved by acid rain
4 types of transportation
suspension
traction
solution
saltation
what is traction?
heaviest rocks roll along sea floor
What is saltation ?
Small pebbles bounce along sea floor
What is suspension?
fine sand floats
What is solution (transport)?
Soluble material dissolves
Why does sediment get deposited?
when water looses energy
What is a discordant coastline?
you have different bands of rock running perpendicular to coastline.
What is a concordant coastline?
A concordant coastline has the same type of rock along its length. The alternating bands of hard and soft rock run parallel to the coast.
coves form here
How is a wave cut notch platform formed?
a cliff with a high tide and low tide
by hydraulic action and abrasion base of cliff eroded and forms a wave cut notch
top bit falls down forming a wave cut platform and process repeats.
How is a stump formed?
a crack in a headland widens into a cave by hydraulic action and erosion methods
cave opens up into an arch
arch falls in creating a stack
stacks erodes and shrunk into a stump
until stump is gone leaving another headland #for process to repeat.
How do coves form?
form on a concordant coastline.
when a narrow entrance is made through resistant rock as it shard to erode.
but space opens up as soft rock is much easier to erode
What is longshore drift?
The movement of material along a coast by waves which approach at an angle to the shore but recede directly away from it.
Longshore drift and spit formation?
what else does this form?
prevailing wind at 45° to coast and swash
back wash is 90°
process repeats in zigzag pattern
when reach end of coastline sediment deposited
prevailing wind changes direction forming a hook.
creating a saltmarsh
What is hard engineering?
artificial structures are used to reduce levels of erosion and protect the coastline
What is a sea wall?
cost, +, -
concrete barrier placed near cliff , curved lip to reflect wave
£5000-£10000 per metre
+ effective
- unnatural, expensive
types of hard engineering (sea) ?
sea wall
groynes
rock armour
gabions
What are groynes?
cost, +, -
timber structure built to trap sediment and enlarge beach which can act as a buffer.
£150000 each (200m)
+ wider beach, cheaper
- starve beach further along, unnatural
What are gabions?
cost, +, -
wire cages filled with rocks, built up to support cliffs, provide a buffer
£50,000 (100m)
+ cheap, improve draining
- unattractive only last 5-10 years
What is rock armour?
cost, +, -
piles of large boulders at cliff base rock absorbs wave energy.
£200,000 (100m)
+ cheaper, more natural
- expensive to transport
What is soft engineering?
creating or enhancing natural structures that use natural processes to prevent erosion and floods.
Types of soft engineering (sea)?
beach reprofiling
dune regeneration
dune fencing
What is beach reprofiling?
cost, +, -
add sediment to beach so it is wider make it steeper so its harder for waves to travel up to cliff.
£50000 (100m)
+ cheap, natural
- constant maintenance
What is dune regeneration?
cost, +, -
dunes act as a buffer but are easily damaged by trampling and storms.
marram grass can be planted to help develop dunes as they trap sediment.
£200-2,000 (100m)
+ cheap, natural
- time consuming, damaged easy
What is dune fencing used for?
fences on a sandy beach along dunes to protect them and prevent people trampling and encourage new dune formation
£400-2000 (100m)
+ cheap, minimal impact
- unsightly, regular maintenance after storms
