coasts DEFINITIONS

landscape

the visible features (landforms) of an area on the Earth's surface

system

a group of objects and the relationship between them

millenia

a timescale of thousands of years

kinetic energy

the capacity to do work as a result of motion

potential energy

the capacity to do work that a body posesses by virtue of its position and that is potentially transferrable into another form of energy

thermal energy

the capacity to do work as a result of heat

geomorphic processes

processes resulting in the formation and shaping of lanforms and landscapes

nearshore zone

the area of coastal environment between mean high tide and mean low tide.

open systems

a type of system whose boundaries are open to both inputs and outputs of energy and matter

input

the addition of energy or materials to a system

output

the transfer of energy and/or materials out of a system

deposition

the laying down of sediment transported by rivers, waves, glaciers and wind, as energy levels decline

weathering

the in situ breakdown of rocks at, or near, the land surface by physical, chemical and biological processes.

mass movement

the downslope transportation of material under gravity.

erosion

the wearing away and/or removal of rock and other material by a moving force.

evaporation

the process by which liquid water is converted into a gaseous state

stores

the parts of a system in which material and/or energy accumulates.

longshore drift

the movement of sediment by waves and currents along a coastline.

equilibrium

a long-term balance between inputs and outputs in a system.

dynamic equilibrium

a system displaying unrepeated average states through time.

negative feedback

an automatic response to change in a system that restores equilibrium.

sediment cell

a stretch of coastline and its associated nearshore area within which the movement of coarse sediment, sand and shingle is largely self-contained.

closed system

a system with inputs and outputs of energy, but wiothout any movement of materials across system boundaries.

fetch

the distance of open water in one direction from a coastline, over which the wind can blow.

aeolian processes

erosional, transportational and depositional processes by the wind

wave period

the time period between successive wave crests arriving at a given point

swell waves

a relatively smooth ocean wave that travels some distance from the area of its generation.

storm waves

a wave generated locally by high wind energy

crest

the highest point of a wave

trough

the lowest point of a wave

wave height

the vertical distance between trough and crest

wavelength

horizontal distance between the crests or between the troughs of two adjacent waves

spilling waves

Waves fomed over a long gently sloping sea bed.

plunging waves

Waves formed over a moderately sloping sea bed.

surging waves

waves formed over a steeply sloping sea bed.

swash

the movement of water up a beach after a wave has broken

backwash

flow of water down a beach after a wave has broken

constructive waves

waves in which the swash is more powerful than the backwash

destructive waves

waves in which the backwash is more powerful than the swash

inshore

Area between the LWM (low water mark) and the point where waves cease to have an influence on the land

foreshore

the area exposed when the tide is out (low tide) and submerged when the tide is in (high tide).

backshore

the areas of the shore which is submerged only during the highest tides and severest storms

breaker zone

near shore area where waves first begin to break

surf zone

the region between the breaking waves and the beach

swash zone

the part of the beach dominated by swash and backwash

foredune

the closest dune to the ocean or the first dune in a sand dune system

tide

the periodic rise and fall of the sea level under the gravitational pull of the moon and sun

tidal range

the vertical difference in height between consecutive high and low waters over a tidal cycle

geology

the study of the earth, specifically rocks and the planet's crust

lithology

the chemical and physical characteristics of rock types

structure

the physical characteristics of rocks, including their jointing, bedding, faulting, angle of dip etc.

discordant

a coastline with bands of different geologies lying perpendicular to the coastline

concordant

a coastline with bands of different geologies lying parallel to the coastline

planform

the shape of a landscape as viewed from above

rip currents

strong and relatively narrow currents of water that flow seaward against breaking waves

cusps

a pointed and regular arc pattern of sediment on a beach

ocean currents

the large scale horizontal flow of ocean water (at the surface and at depth) driven by planetary winds and contrasts in water temperature and salinity.

sub-aerial processes

a collective term for weathering and mass movement processes

sediment budget

the balance of sediment volume entering and exiting a particular section of the coast

mechanical weathering

disintegration of rocks by physical forces, like pressure release, ice wedging, freezing and thawing, exfoliation

freeze-thaw

a mechanical weathering process caused by water, confined in rock joints, expanding as it freezes, and as a result breaking rocks into smaller particles

pressure release

the disintegration of rocks caused by a release of pressure by the removal of overlying mass.

thermal expansion

increase in volume of water due to its rise in temperature

salt crystallisation

a mechanical weathering process whereby formation of salt crystals leads to disintegration of rocks

chemical weathering

decomposition of rocks by chemical processes leading to the creation of new chemical componds.

oxidation

a chemical process that weathers certain types of rock and involves the absorption of oxygen from either the atmosphere or water by rock minerals

carbonation

a chemical weathering process whereby carbon

solution

the chemical weathering process by which rock minerals are dissolved

hydrolysis

A chemical reaction that leads to decomposition of rocks by the addition of water.

hydration

the breakdown of rocks by cycles of wetting (expansion) and drying (contraction)

biological weathering

the breakdown of rocks through the chemical and physical action of living organisms e.g. burrowing, tree roots etc.

root action

the biological weathering process by which rock is broken apart as roots grow and expand

burrowing

the biological weathering process caused by animals digging.

chelation

a type of chemical weathering caused by acids derived from rainwater and organic material

regolith

a loose layer of rocky material overlying bedrock

rockfall

a mass movement process affecting steep slopes over 70 degrees in angle

slide

a mass movement process where cohesive material moves downslope along a straight slip plane.

slump

a mass movement process where material moves downslope along a curved slip plane

abrasion

an erosion process whereby material being transported rubs against surfaces leading to smoothed surfaces

attrition

the erosion of sediment transported by rivers, glaciers, waves and winds leading to smaller rounder particles

hydraulic action

the erosion process by which water forces air into cracks in the rock leading to disintegration

pounding

The erosion process where the sheer force of the water crashing into a surface leads to disintegration.

corrosion

The decomposition of rock due to a chemical reaction with water

traction

the transport process by which large material is rolled along the river or sea bed.

saltation

the transport process by which material is hopped or bounced along the bed

suspension

the transport process by which fine material is carried by the energy of the water

solution transport

the transport process by which minerals are dissolved and carried by the water

settling velocity

the speed required for suspended particles of a given size, transported by rivers, the wind, tidal currents, to be deposited.

marine processes

processes operating upon a coastline that are connected with the sea, such as waves, tides and longshore drift.

fluvial processes

processes involving the work of running water on the surface of Earth

flocculation

a process by which salt causes the aggregation (clumping) of minute clay particles into larger masses that are too heavy to remain suspended in water

deflation

erosion caused by wind that blows away small sediment.

surface creep

the slow movement of particles on the surface caused by being struck by particles in transport

erosional landforms

the category of landforms shaped predominantly by erosion processes

cliffs

rugged steep or vertical landforms found on coastlines.

shore platforms

A smooth erosional surface that develop in the surf zone adjacent to coast lines.

strata

layers of rock

bay

an inlet along a coastline, usually between two headlands

headland

a promontory extending out from the coastline

wave refraction

the process by which waves slow down and wave crests bend towards due to the uneven shallowing of water.