Coastal Systems and Landscapes

AQA A-Level Geography

Abrasion

Erosion by pebbles carried by waves grinding against the rock like sandpaper,

Accretion

The opposite of erosion, an accumulation of sediment deposited by waves.

Arch

An erosional landform formed where a wave has fully eroded through a headland.

Attrition

An erosional process in which pebbles and rocks knock against each other as they are carried by waves, becoming smaller and rounder

Barrier Beach/Island

A stretch of sand or shingle above high tide that runs parallel to the coastline, and is separated from it by a lagoon. Barrier beaches are connected to the mainland at one end, barrier islands are not.

Berm

Ridges of shingle found towards the back of a beach.

Biological weathering (3 examples)

The break up of rocks in situ by plants or animals (e.g. plant roots, burrowing, human footsteps)

Cave

A large natural opening in the rock where wave energy has been concentrated on a cliff face.

Cavitation

The enlargement of fissures in rocks where air has been compressed and released by waves crashing into joints.

Climatic Climax Community

The final stage of plant succession, where species composition remains stable and at its largest point.

Coastal morphology

The shape and structure of coastal systems.

Constructive wave

Low energy waves that result in net accretion (growth of beach), as they have stronger swashes than backwashes

Corrosion

A process of chemical erosion where acidic water seeps into and dissolves rocks like chalk or limestone.

Cost-Benefit Analysis

A study that evaluates the costs and benefits of a particular coastal defence or management plan.

Cusp

A crescent-shaped indent that forms where shingle and sand meets, and concentrates swash energy.

Dalmatian Coast + example

Where ridges and valleys run parallel to the coast, forming offshore islands as sea level rises e.g. in Croatia

Destructive Wave

High energy waves that result in net erosion (shrinking of beach), as they have stronger backwashes than swashes

Double spit

Where two spits extend from the opposite sides of a bay towards the middle, formed by longshore drift acting in opposite directions

Drift-aligned beach

A beach where waves approach at an angle, allowing sediment to be transported by longshore drift.

Emergent Coastline

Coastlines formed from either a drop of sea level or an uplifting of the land

Environmental Refugee (+ 2 examples)

A person who has been displaced by changes to their natural environment e.g. Rising sea levels, destructive storms

Eustatic change (+ 3 examples)

A change in sea levels e.g. thermal expansion, melting ice, change to shape of ocean basin

Fjord

A glacial valley now filled by seawater, characterised by its steep cliffs, "U-shaped" valley, and its long reach inland

Halophyte

A plant that is able to live in waters of high salinity (saltiness)

Hard-engineering (+3 examples)

The use of concrete and large artificial structures to "hold the line", and defend against coastal erosion e.g. groynes, rip rap, sea walls

High-energy coastline (+ 2 landforms)

Coasts that experience strong winds and intense storm seasons, and as a result may see high rates of erosion and the formation of cliffs and headlands.

Integrated Coastal Zone Management (ICZM)

Strategies formulated by national and local governments to manage coastlines using a holistic approach (taking all voices into account) with the aim of environmental, social, and economic sustainability.

Isostatic Change (+ 2 examples)

When the land rises or falls relative to the sea (e.g. due to changes in ice volume, tectonic processes like the formation of mountains)

Isostatic Recovery + example

When land rises as a result of the reduced weight of ice following the end of a glacial period (e.g. +1mm per year in Scotland)

Isostatic subsidence + example

When land sinks to counteract isostatic recovery elsewhere (e.g. -1mm per year in England)

Landform

A feature of coastal topography formed by erosional/depositional processes

Landscape

A collection of landforms spanning an entire stretch of coast.

Landslide

The sudden collapse of rock and soil down a slope.

Lithology

The composition and structure of rocks

Longshore drift

The transportation of water and sediment down a beach caused by waves hitting the shore at an angle compared to the direction of the backwash.

Low-energy coastline (+ 2 landforms)

Coasts that experience weak winds and less intense storms, and as a result may see low rates of erosion and the formation of beaches and spits.

Mass Movement

The downhill movement of cliff material under the influence of gravity, the four types are: landslide, mudslide, rockfall, and slumping.

Mudflat

Coastal wetlands that form when mud is deposited by tides or rivers. They are only exposed at low tide.

Mudflow

Where saturated soil with limited vegetation to bind it together is lubricated by heavy rain and flows over cliff slopes.

Offshore bars

Offshore ridges of sand or shingle running parallel to the coast

Pioneer species

The first species to populate an area during primary succession

Raised beach

A formed beach separated from wave action due to a relative fall in sea levels.

Recurved tip

A spit with a curved end, as wave refraction carries material round into the more sheltered water behind the spit

Ria

A submerged river valley connected to the coastline

Rip currents

A strong, narrow flow of water that flows away from a beach and up to 90m into the ocean, poses a significant threat to human life.

Rockfall

A sudden form of mass movement where fragments of weathered rock break away from the cliff.

Runnels

Depressions running parallel to beach ridges that allow water to return to the ocean.

Saltation

Transportation of heavy pebbles by dragging and bouncing along the river bed.

Saltmarsh

Areas of flat silty sediments that accumulate in sheltered coastal areas like estuaries. They are the climatic climax once halophytic plants colonise it.

Sand Dune

Mounds of sand formed where the wind has deposited sand, particularly along obstacles on the beach

Scree

An accumulation of rock fragments at the base of a cliff, most commonly formed by freeze-thaw weathering or acid rain

Sediment budget

The balance of inputs and outputs in a sediment cell system, determines whether the system is in equilibrium

Sediment cell

Stretches of coast within which the movement of material is largely self-contained. There are 11 primary cells in England and Wales.

Shoreline Management Plan (SMP)

A strategy for managing coastal flood and erosion risk for a particular stretch of coastline over both the short and long term.

Slump

A type of mass movement where saturated soil slips down a curved surface.

Soft-engineering (+3 examples)

A sustainable approach to managing the coast without using artificial structures e.g. beach nourishment, managed retreat, dune stabilisation.

Soil Creep

Very slow movement of soil down a hill, caused by the increased weight of damp soil pushing itself forwards

Solifluction

The gradual movement of saturated soil down a slope, occurring over multiple freeze-thaw weathering cycles

Solution

Where dissolved minerals are carried by the body of water

Spit

Where beach material deposited by longshore drift stretches out into the sea, but remains connected to the mainland at one end.

Stack

An isolated pillar of rock formed where the top of an arch has collapsed.

Stump

The remains of an eroded sea stack

Submergent coastline

Coasts that are being flooded by ocean waters because of a relative rise in sea level.

Suspension

Where light, insoluble sediment (e.g. silt, clay particles) are carried aloft through the body of water.

Swash-aligned beach

Where waves approach parallel to the coast, resulting in a parallel swash and backwash, and preventing longshore drift

Tidal range

The difference in elevation between high and low tide for a given location.

Tides

The daily rise and fall of the ocean's surface influenced by the moon's gravity pulling on earth

Tombolo (+ example)

A narrow beach connecting an island to the mainland e.g. Chesil Beach connecting Dorset to the Isle of Portland

Traction

Where heavy stones roll along the bottom of the river/sea as a form of transportation

Vegetation Succession

The evolution of plant communities at a site over time, from pioneer species to climax vegetation.

Wave quarrying

A process of physical weathering where tall, high energy waves enlarge joints and break off chunks of rock

Wave refraction

The bending of waves as they approach an irregular coastline resulting in a high concentration of wave energy at a headland and lower energy concentration in a bay.

Why does wave refraction occur in the ocean?

Waves centred on the headland enter shallower water earlier, meaning friction increases, wave speed and wavelength decreases, and the waves converge towards the normal while the waves in deeper water do not.

Wave-cut notch

A dent in a cliff, usually at high tide level, where the concentration of wave energy has exacerbated erosion. Once the notch grows large enough that section of cliff will become unstable and collapse

Wave-cut platform

A rocky, flat area sometimes found between a cliff and the low tide mark where the former cliff has been eroded away.

Factors affecting wave energy (x3)

Long fetch, high pressure gradient, duration of time over which wind has blown

Neap tide

Tides with the smallest daily range (high low tide, low high tide) that occur when the moon and sun are at perpendicular angles to the Earth (1st and 3rd quarter)

Spring tide

Tides with the highest daily range (low high tide, high low tide) that occur when the moon and sun are at parallel angles to the Earth (high high tide, low low tide)

Chelation

A form of chemical weathering where organic acids produced by plant roots and decaying matter bind to metal ions in rocks.

Carbonation

A form of chemical weathering where Carbon dioxide in the air reacts with carbonate minerals to form carbonic acids that break down rock

Freeze-thaw weathering

A process of physical weathering where repeated cycles of freezing and thawing expand fissures and weaken rocks.

Entrainment

Movement of material by an agent (river, glacier, wave), - does not include mass movement.

Salt crystallisation

A type of physical weathering where salt crystals are deposited into rock cracks, applying pressure and widening the cracks

Regolith

Looser rocks like soil that are more easily transportable

Lagoon

A shallow body of salt water separated from the sea by a narrow landform like a barrier beach or a peninsula

Brackish water

Water with a salinity level in between fresh and saltwater e.g. estuaries

Estuary

The transition zone between a river and the open sea, an important wildlife habitat

Cape

A large headland that occurs where a coast changes direction (e.g. Cape of Good Hope, South Africa)

How does solar energy impact the coast?

Allows photosynthesis, thus creating habitats and facilitating biological weathering, plus differential heating over the Earth's surface causes wind energy which affects waves.

How does wave energy impact the coast?

Level of wave energy determines coastal landforms like headlands, bays, beaches, cliffs, spits.

How does tidal energy impact the coast?

High tidal range creates powerful tidal currents and increase rate of sediment transportation, while low tidal range causes formation of wave-cut notches and wave-cut platforms as wave energy is concentrated on one section of cliff.

How does geothermal energy impact the coast?

Influences geology & rock type, which affects erodibility and the landforms that can form, plus tsunamis