Coastal Environments and Processes

A set of vocabulary flashcards covering coastal processes, landforms, erosion mechanisms, sediment transport, and related events as described in the notes.

Coasts

The meeting point of land, sea and atmosphere.

Waves

Oscillation of the water surface.

Wave height

Vertical distance between the crest and trough.

Wave length

Horizontal distance between two successive crests or troughs.

Wave frequency

The number of waves passing a fixed point in a given period of time.

Crest

Highest point of a wave.

Trough

Lowest point of a wave.

Fetch

Distance that the wind has travelled across the water surface.

Swash

Forward movement of water up the beach.

Backwash

Movement of water down the beach.

Breaking waves

Waves break when the water depth is too shallow to support the whole oscillation.

Spit

Long narrow ridge of sand that extends from the coastline into the sea.

Longshore drift

Transfer of sediments along the coastline caused by waves approaching the coast at an angle.

Constructive waves

Swash is greater than backwash; long wavelength; low height; low energy; deposit material on beaches.

Destructive waves

Backwash is greater than swash; high energy; erode the beach.

Wave refraction

Variation of water depth along the coastline causes waves to slow and bend toward headlands, concentrating energy there and causing erosion; bays tend to deposit.

Tides

Regular movements in the sea’s surface caused by the gravitational pull of the Moon and Sun.

Spring tides

Low spring tides after a new moon; high spring tides after a full moon.

Neap tides

Tides when the Sun and Moon are at right angles to the Earth.

High tide

The highest water level in the tidal cycle.

Low tide

The lowest water level in the tidal cycle; exposes beaches and mudflats.

Mudflats

Flat areas of mud exposed at low tide.

Rock pools

Pools formed by tidal action that provide habitats for marine organisms.

Storm surges

Temporary rise in sea level above predicted tide caused by low pressure and strong winds in storms.

1953 North Sea Storm Surge

Storm surge event that caused about 2,500 deaths in the Netherlands and the UK.

Cyclone Nargis (2008)

Myanmar cyclone whose storm surge inundated the Irrawaddy Delta, causing many deaths.

Superstorm Sandy (2012)

Storm surge that flooded parts of New York and New Jersey.

Sediment cell / Littoral cell

A section of coastline that is open and in dynamic equilibrium between erosion and deposition.

Sources (sediment cell)

Weathered cliffs, beach material, offshore bars, river sediment, and in-drift from adjacent littoral cells; sometimes beach nourishment.

Sinks (sediment cell)

Offshore bar, beaches, sand dunes, or out-drift to the next sediment cell.

Transfer (sediment cell)

Longshore drift and tidal action moving sediment within the cell.

Hydraulic action

The sheer force of moving water that exerts pressure and erodes rock.

Wave quarrying / cavitation

Compression of air in rock openings as a wave hits; decompression as it recedes, weakening the rock and allowing erosion.

Corrasion / abrasion

Pieces of rock carried by waves act like sandpaper, smoothing rock and forming notches and wave-cut platforms.

Solution

Chemical erosion where soluble minerals (e.g., calcium carbonate) are dissolved and carried away.

Attrition

Particles in the load collide and become smaller and lighter.

Bay of Fundy

Canadian coast known for extreme tides and erosion evidence.

Discovery Bay, Jamaica

Location noted for biological weathering by marine organisms.

Slaking

Disintegration of materials when exposed to water.

Mass movement

Down-slope movement of rock/soil due to gravity.

Slumping

Downward movement of material along a curved slip plane, often with unstable blocks.

Rockfalls

Sudden collapse of rock from a cliff.

Cave

A sea-eroded recess formed along weaknesses in rock.

Arch

A curved tunnel formed when two caves join on opposite sides of a headland.

Stack

An isolated vertical rock pillar left after an arch collapses.

Stump

Remnant of a stack after further erosion at sea level.

Wave-cut notch

Indentation at the base of a cliff formed by hydraulic action and abrasion.

Wave-cut platform

Flat rock bench formed at the base of a cliff as the cliff retreats.

Cliff retreat

Retreat of the cliff face due to ongoing erosion.

Cathedral Cove

Erosional coastal landform example in New Zealand.

Lithology

The physical characteristics or rock type that influence erosion resistance.

Uniform resistance

Rocks with the same resistance throughout; erode relatively evenly.

Less resistant at base

Rocks that erode more quickly at the base, aiding cliff collapse.

Less resistant at top

Rocks that erode rapidly near the top, contributing to cliff retreat.

Strata dipping inland

Layers dipping away from the sea; generally stable.

Strata dipping to the sea

Layers dipping toward the sea; often unstable.

Impermeable over permeable

Stable arrangement where impermeable rock lies above permeable rock.

Permeable over impermeable

Unstable arrangement where permeable rock lies above an impermeable layer.

Wave energy

Energy carried by waves; higher energy increases erosion.

Wave type

Destructive waves erode more than constructive waves.

Coastal configuration

Natural arrangement of headlands and bays along a coastline.

Human activity

Coastal defenses and construction that affect erosion and deposition.

Dynamic equilibrium

A balance between erosion and deposition along a coast.

Mudflats

Flat, tidal flats formed where deposition outpaces erosion.

Headland

A prominent, resistant promontory that erodes less and forms features like archs and stacks nearby.

Bay

A recessed, lower-energy area of the coast where deposition is common.

Offshore bars

Sediment bars formed offshore that influence beach processes.