coastal landscapes

The littoral zone

a series of sub-zones to represent the features of the wider coastline from sea to land

• offshore, nearshore, foreshore and backshore

• This zone reaches dynamic equilibrium where there is a balance between inputs and outputs

high energy coastline

• Destructive waves, long fetches, high rates of erosion, caves, arches, stacks and stumps, cliffs and wave-cut platforms.

low energy coastline

Constructive waves, shorter fetches, higher rates of deposition, spits and bars, beaches, sand dunes and salt marshes

concordant coastline

alternating bands of hard and soft rock parallel to the coast.

discordant coastlines

have alternating bands of hard and soft rock at 90^o to the coast.

• Erosional landforms are more common on discordant coastlines because erosion happens at different rates along their length.

coastal morphology

the shape of the coastline is continually changing

bays and headlands

• On discordant coastlines, the retreating, less resistant rock and the exposed resistant rocks cause a change in the shape of the coastline. This leads to wave refraction.

• This change in the way in which waves approach the coastline can cause an increase in the rate of erosion on the headlands.

• This leads to the formation of headland features like caves, arches, stacks and stumps.

Dalmation coastline

• formed as a result of tectonic forces and sea level rise

• series of islands which run parallel to the coast

• e.g croatia

Haff coastline

Along the southern Baltic coastine

• Large amounts of sand and gravel deposited offshore during the glacial period

• a feature of a low energy coastline

geological structure

• Strata - layers of rock

• Bedding planes - horizontal cracks created by pauses in rock formation

• Joints - vertical cracks caused by tectonic movement or contraction

• Folds - the result of pressure during tectonic movement causing the rock strata to fold

• Faults - the result of stress or pressure causing it to fracture

• Dip - the angle of the rock strata

Cliff profiles

The angle and height of the cliff face

• features such as wave cut platforms

what affects cliff profiles

• lithology

• Hydraulic action and abrasion 

• Subaerial processes 

• Wave type

what is coastal recession due to

• Erosion

• Sea level rise

• Submergence

Mineral composition

Rock classification

Structure

Mineral composition

Some minerals are more reactive than others

• This affects the rate of chemical weathering for example:

  • Calcite is reactive and so easily chemically weathered 

Sedimentary rocks

form as a result of compaction and cementation of sediment called lithification

• shales, sandstone, and limestone

• Sedimentary rocks: 

  • Erode and weather more rapidly than other types of rock

  • Form in layers

  • They are clastic which means they are made of clasts (sediment particles)

metamorphic rock

form when sedimentary and igneous rocks are altered through heat and pressure, but do not melt in the process

• slate and marble

• Metamorphic rocks:

  • Have a crystalline structure

  • Are often folded and faulted

  • Are more resistant than sedimentary rock and less resistant than igneous rocks

Igneous rock

form when molten rock from the Earth's mantle cools and hardens

• granite and basalt

• Igneous rocks:

  • Erode and weather very slowly

  • Can be categorised into two types:

    • Intrusive igneous rock - forms within the ground, cools slowly, and has large course crystals 

Differential erosion

the changing rates of erosion

• Leads to complex cliff profiles

• Influences rates of recession

Role of vegetation

• Help stabilise coastlines- The plant roots help to bind the soil/sand together reducing the impact of erosion

• infiltration- improve soil structure

• regulate climate

pioneer species

The fist plants to grow in the harsh coastal environment

• help stabilise sediment

• trap sediment

Sand dune succession

The changes in an ecosystem, over time, of the species that occupy it

An example of pioneer species

• Sandy beaches usually have sand dunes at their rear, because of strong onshore winds transporting dried, exposed sand

• Sand grains are trapped and deposited against any obstacle (rubbish, rocks, driftwood etc) and begin to form embryo dunes

• It is the interaction of winds and vegetation that helps form sand dunes

Formation of a sand dune

• Windblown sand is deposited against an obstruction: Pebbles or driftwood

• As more sand particles are caught, the dunes grow in size, forming rows at right angles to the prevailing wind

• Over time, the ridges of the dunes will be colonized and fixed by vegetation in a process called succession