Coasts- Processess

WAVE CREST

This is the top of the wave as water in a wave rises causes crest

WAVE TROUGH

As water in a wave falls

WAVE HEIGHT

Distance between the wave crest and trough

WAVE FREQUENCY

Number of waves that break on a beach in a given period of time

SWASH

The body of foaming water that rushes up the beach when the wave breaks.It obtains its energy from the energy released by the breaking wave

BACKWASH

The water which returns down the beach after a wave has broken

ABRASION

The wearing away of the shoreline by sediment carried by waves.Also erosion by friction scraping, scouring and rubbing of load in contact with banks and bed.

ACCRETION

The accumulation of marine sediments.Where deposition exceeds erosion.

ARCH

Wave-eroded passage through a small headland

ATTRITION

Particles are reduced in size and rounded off by colliding with one another as they are washed in the waves

BAR

Coarse grained deposit of sediment extending across the mouth of a bay sometimes reaching the other side and sealing off the entrance

BERM

Low hill of sand or gravel that forms at the upper limit of the swash.They are short term features and are removed by successive tides and storms.

BLOW-HOLE

A chimney or pipe leading from a cave up through cliff to the surface.Caused by erosion and often exploitation of joints in the geology.

CONSTRUCTIVE WAVES

Low frequency waves of 6-8 waves per minute which have elliptical water motion, powerful swash and weak backwash. They have low energy and deposit sediments.

CONCORDANT COAST

The alignment of geological outcrops which are parallel to the coastline, i.e. Dorset Coast, lulworth

CORRASION

Erosion by friction of load in contact with banks and bed, ABRASION

CORROSION

Includes the dissolving of carbonate rock i.e. limestone in sea water and the evaporation of salt crystals which expand on formation and help the rock to disintegrate.

CUSP

Crescent-shaped embayments developed on beaches of mixed sediments

CUSPATE FORELAND

Is a triangular accumulation of sand and or gravel located along the coastline.This feature is formed by longshore drift from opposing directions, i.e. Dungeness

DELTAS

Form when the amount of sediment delivered at the mouth of a river exceeds the amount removed by waves and trial currents.

DESTRUCTIVE WAVES

High frequency 13-15 waves per minute which have circular water motion(oscillatory).with a weak swash and strong backwash,they erode THEY DESTRUCT A COASTLINE AND ARE HIGH ENERGY WAVES

DISCORDANT COAST

Coasts which cut across the rock structure i.e. Dorset north of Swanage Bay

DOWN DRIFT

In the direction of the net longshore transport of beach material

DUNES

Concentrations of mound like landforms composed of sand that has been blown off the beach by onshore wind. Embryo dunes first followed by foredunes(yellow) grey dunes, then wasting dunes.

EUSTATIC

Changes in sea level caused by variations in the amount of water in the oceans.

FETCH

The distance of uninterrupted water surface over which the wind has blown to form waves, longer fetch means higher energy waves

FLOOD

A temporary excess of water that spills over onto land

HYDRAULIC ACTION

Fore exerted by moving water on the bed and banks of a river.

ISOSTATIC

Changes in sea level resulting from the rise and fall of land masses

LONGSHORE DRIFT

LSD Movement of sediment in a zig zag pattern up and down the shore with swash and backwash resulting in an overall direction along the coast

MASS MOVEMENT

Non-marine processes often seen on cliffs like slumping, land slides and soil creep caused by gravity and often exacerbated by rain

PSAMMOSERE

Succession of stages of plant growth forming colonisation of bare sand to climax vegetation

RECESSION

COASTS=RETREAT

RIA

A river valley drowned usually because sea level has risen but it could be because the land level has fallen i.e. adur ouse estuaries

Saltation

Sand bounces across the surface of the beach blown by wind

SEDIMENT CELL

A length of the coastline in which the movement of sediment (sand, shingle) is largely self-contained

SEDIMENT SINK

Point or area at which beach material is irretrievably lost from a coastal cell, such as an estuary or a deep channel in the seabed.

SLUMPING

Large quantity of lubricated soft rock moves over resistant rock on a concave surface

SPIT

Long ridges of sand and shingle attached to land at one end i.e. Hurst castle spit and spurn head

STACK

A residual post of rock resulting from the continued erosion of the arches i.e. old harry rock

Subaerial Processes

Weathering

-biological

-physical

-chemical

Mass movement

-earth flows

-mudflows

-slides

-slumps

-rockfall

-blown material and runoff

PROCESSES THAT HAPPEN ABOVE WATER

TOMBOLO

Shingle ridge linking the mainland to an island i.e. Chisel Beach

UPDRIFT

The direction opposite to predominant LSD movement of beach material

WAVE CUT PLATFORM

A flat rock area in the intertidal zone created by destructive waves also often by chemical weathering if in a limestone area

WEATHERING

The breakdown of rocks in situ (in their original location without them being moved away). This produces finer particles that can be removed by agents of erosion such as wind, running water and gravity

Lithology

The physical characteristics of a rock or stratigraphic unit.