coasts knowledge

sediment

loose solid material such as rocks shells and sand

erosion

the process of wearing away rock of the land often by water and waves erode the coast

deposition

the process of sediment being dropped somewhere by water

waves deposit sediment when water slows down waves lose their energy

waves

caused by wind blowing over the sea

fetch

distance the wind blows across open water

longer the fetch the bigger and more powerful the wave

prevailing wind

the wind direction most of the time

UK= southwest

swash

movement of waves up the beach

direction of the prevailing wind

backwash

movement of waves back down a beach at a right angle

constructive waves

stronger swash than backwash so deposit sediment low slow and calm

destructive waves

stronger backwash than swash so erode the coast high fast and strong

weathering

breaking down and weakening of rocks

mechanical weathering

the physical disintegration of rocks

freeze thaw weathering water freezing through cracks expanding and widening

chemical weathering

transformation of rocks due to chemical reactions

mass movement

downward movement of material under the force of gravity

rock falls

rock breaks away often due to freeze thaw weathering

sliding

blocks of rocks slide down a cliff

slumping

collapse of saturated or weak rocks along a curved surface

hydraulic power

caused by the force of waves crashing against a cliff compressing air into cracks

abrasion

when rocks in the water strike the cliffs the friction from these materials hitting the land is similar to the action of sandpaper wearing away of rocks

attrition

is when rocks in the water are hitting eachother over time these fragments become smaller and smoother due to the continuous impacts

solution

is a process where certain types of rocks are dissolved by the acidity in the sea water

geology

types of rocks clay, softer rocks erode more easily harder rocks such as chalk are more resistant to erosion

concordant coastlines

have layers of rock running parallel to the sea

discordant coastline

have alternating layers of rocks perpendicular to the sea

formation of headlands and bays

found on discordant coastlines

softer rocks is eroded more by destructive waves to form bays

harder rocks such erodes more slowly and is left protruding into the sea as headlands

formation of caves arches and stacks

headland is eroded by hydraulic power and abrasion

weaknesses in the headland are widened to form cracks then caves

the cave erodes all the way through the headland to form an arch

top of arch collapses as it is unsupported to form a stack

formation of wave cut platforms

base of the cliff is eroded forming a wave cut notch

cliff above the notch is unsupported so collapses

cliff above the water level retreats leaving a wave cut platform

beach

accumulated sediments such as sand pebbles or gravel deposited by constructive waves

formation of sand dunes

material is deposited on the beach by constructive waves

winds blowing on shore blows the sediment up the beach

and obstacle traps the sediment forming an embryo dune

eventually plants begin to grow in the dune

dune continues to grow - mature dune

transportation

movement of sediment along a beach

long shore drift

movement of sediment along a beach

swash pushes sediment onto the beach at angle prevailing wind

backwash pulls sediment off the beach at a right angle due to gravity

zig zag pattern

formation of spits

if longshore drift is not stopped by something then the sediment will continue to be transported along the beach

sediment being transported builds up and starts to protrude the sea -a spit

formation of bars

when a spit keeps growing until it reaches another piece of land

case study of coastline

holderness coast

northeast of england

flamborough head is a headland made of chalk caves arches and stacks as well as wave cut notches and platforms are found here

spurn head is a spit caused by long shore drift

hard engineering

artificial structure built to control the sea and protect the coastline: sea walls groynes gabions and rock armour

soft engineering

working with nature to manage the coastline in a more natural way: beach nourishment and dune regeneration

managed retreat

not building defences allowing low value land to flood naturally

case study of coastal management

walton on the naze essex population of 6000

rapid erosion 2m per year

sea walls and groynes built in 1977 in front of the town effective