Coastal Landforms & Processes: Erosion, Sediment Transport, and Subaerial Weathering

What is the main source of energy at the coast?

Waves

How are waves generated?

By wind through friction between wind and water surface.

What factors affect wave energy?

Fetch, duration, and strength of the wind.

What is wave height?

The distance from the peak to the trough.

What is wave length?

The distance from crest to crest.

What is wave frequency?

The number of waves passing a specific point over a given time.

What are the two main types of waves?

Constructive and destructive waves.

How do constructive waves affect beach morphology?

They build up the beach with a gentle profile.

What is a storm berm?

A formation that develops in winter when large destructive waves carry larger sediment further up the beach.

What is abrasion in coastal erosion?

Sediment and stones picked up by waves wear away at cliffs or headlands.

What is hydraulic action?

The shear force of waves forcing air into cracks in the cliff, weakening the rock.

What is corrosion in coastal processes?

Weak acids in seawater dissolve rock particles.

What is attrition in coastal erosion?

Rocks moving around in water knock into each other, becoming smaller and rounder.

What factors influence the rate of coastal erosion?

Wave type, wave size, and lithology.

What is a wave-cut platform?

A flat area formed at the base of a cliff due to hydraulic action and abrasion.

How does wave refraction affect headlands?

It concentrates wave energy onto the headland, leading to increased erosion.

What landforms can result from the erosion of a headland?

Caves, arches, stacks, and stumps.

What is differential erosion?

The process where softer rock erodes faster than harder rock, creating landforms.

How do headlands and bays form?

Through differential erosion and wave refraction on discordant coastlines.

What happens to waves as they approach a bay?

They diverge and weaken, allowing sand and shingle to form beaches.

What is the significance of wave orthogonals?

They illustrate how wave energy converges on headlands.

What is the impact of seasonal changes on beach profiles?

Beaches are steeper in summer and gentler in winter due to wave activity.

What is the role of lithology in coastal erosion?

Weaker rocks erode more quickly, while more resistant rocks erode slowly.

What is the effect of destructive waves on beach morphology?

They can lead to steeper beach profiles and greater variation in pebble size.

What is the process of undercutting?

The creation of a wave-cut notch at the base of a cliff due to hydraulic action and abrasion.

What happens to the roof of a cave formed by erosion?

It eventually collapses due to gravity and lack of support.

What is the importance of understanding wave formation and characteristics?

It is crucial for explaining differences in beach profiles throughout the year.

What are the main sources of material arriving in the sea?

Eroded from cliffs, transported by longshore drift, brought inland by constructive waves, and carried by rivers.

What are the four ways sediment is moved in water?

Traction, saltation, suspension, and solution.

What is the main factor affecting the direction of sediment transport?

The direction of wave attack.

What is longshore (littoral) drift?

The main process of deposition and transportation along the coast, influenced by the angle of wave approach.

How does longshore drift move sediment?

Waves carry material up the beach at an angle during swash and return it down at right angles during backwash.

What is a current in the context of sediment transport?

The flow of water in a specific direction that transports sediment.

What causes surface currents?

Mainly formed by wind.

What are tidal currents associated with?

Rising and falling tides; stronger tidal ranges produce stronger currents.

What happens during deposition?

Occurs when waves lose energy.

What factors can cause waves to lose energy?

Wind slowing or changing direction, friction with the sea floor, and changes in coastline direction.

What type of coastline typically has rocky beaches?

High energy coastlines.

What type of coastline typically has sandy beaches?

Low energy coastlines.

What is the most common depositional landform?

A beach.

What conditions favor beach formation?

Constructive waves in sheltered areas, often during summer.

What is a drift-aligned beach?

A beach where longshore drift moves sediment along the beach as waves approach at an oblique angle.

What is a spit?

An extended stretch of sand or shingle that extends out to sea from the shore, formed by longshore drift.

What is a double spit?

Occurs when two spits extend towards each other from both sides of a bay.

What is a cuspate foreland?

Low-lying triangular-shaped landforms formed from a buildup of sediment where longshore drift from opposite directions meet.

What are bars and barrier beaches?

Bars are raised ridges of sediment offshore, while barrier beaches are formed when spits join two headlands.

What is a lagoon?

A small body of water cut off from the sea, often formed behind a bar or tombolo.

What is a tombolo?

A spit that joins the mainland to an island.

What are salt marshes?

Sheltered areas behind spits and barrier beaches where salt-tolerant species colonize.

What are sand dunes and how do they form?

Sand dunes form in areas with abundant sand and onshore winds, trapping sand and forming rows.

What role do pioneer plant species play in sand dune formation?

They stabilize the dunes by holding the sand together.

What is plant succession in the context of sand dunes?

The process where other plants thrive in the environment created by pioneer species, leading to a dune ecosystem.

What is the primary source of sediment to coastal areas?

Most coastal sediment is brought to the shore by rivers.

What role does cliff erosion play in coastal sediment?

Cliff erosion is an important source of sediment at most coastlines.

What happens to coastlines that are retreating by a few meters a year?

There is a large input of sediment to the coastal zone.

How can wind contribute to coastal sediment?

Wind can transport sediment to the shore, leading to the build-up of sand dunes.

What natural feature contributes to sediment deposition in high latitude coastal areas?

Glaciers break off into the sea, depositing trapped sediment at the coastal zone.

What are Sediment Cells?

Sediment Cells are closed systems where most sediment movement is contained.

How many sediment cells are there around the UK coastline?

There are 11 sediment cells around the UK coastline.

What is a sediment budget?

The sediment budget is the balance between the inputs and outputs of sediment in the system.

What state should coastal systems ideally be in regarding sediment budget?

Coastal systems should be in a state of dynamic equilibrium.

What can disturb the dynamic equilibrium of a sediment budget?

Human activity and natural changes like climate change can disturb it.

What is the significance of Cell 5 in the sediment cells of England and Wales?

Cell 5 runs from Portland Bill to Selsey Bill and is influenced by prevailing winds and waves.

What are the sources of sediment in Cell 5?

Erosion of cliffs, rivers bringing sediment, and sediment moved in from offshore.

What is longshore drift?

Longshore drift is the process that carries sediment eastward along the beaches.

What is soil creep?

Soil creep is the slow downhill movement of soil, common in humid climates, moving less than 1 cm per year.

What is the process of freeze-thaw weathering?

Freeze-thaw weathering occurs when water freezes in rock cracks, expands, and causes the rock to break apart.

What is biological weathering?

Biological weathering occurs when organic activity, such as nesting birds or burrowing animals, breaks down rock.

What is carbonation in chemical weathering?

Carbonation is when slightly acidic rain reacts with carbonate rocks like limestone, causing them to dissolve.

What is oxidation in chemical weathering?

Oxidation is when iron minerals in rock react with oxygen, leading to rust and breakdown of the rock.

What is mass movement?

Mass movement is the downhill movement of material under the influence of gravity.

What are the types of mass movement?

Types include landslides, slumping, rockfalls, soil creep, and flow.

What is a rotational scar?

A rotational scar is a curved, un-weathered, un-vegetated area formed by rotational slumping.

What is a talus scree slope?

A talus scree slope is a fan-shaped mound of debris accumulated at the foot of a cliff.

What characterizes a terraced cliff profile?

A terraced cliff profile is stepped, resulting from the lithology or fractures in the rock.

What factors determine the type of mass movement?

Factors include angle of slope, nature of regolith, vegetation, water, rock type, and human activity.

What causes blockfall?

Blockfall is caused by extreme weathering, rainfall, earthquakes, or hot weather drying out soil.

What is a slump in mass movement?

A slump involves a large area of land moving down the slope in one piece, often leaving a curved surface.