Waves glossary
Wave – the movement of the wind
across the surface of the sea.
Fetch – the distance over which the
wind has blown.
Swash – the transfer of a wave’s energy
up the beach.
Backwash – the transfer of a wave’s
energy down the beach.
KS4 Geography: Coasts
Types of waves
Constructive waves – a wave that has a greater
swash than backwash.
Destructive waves – a wave that has a greater
backwash than swash.
KS4 Geography: Coasts
Processes of erosion
Processes of erosion
Hydraulic action – the waves enter cracks (faults) in the
coastline and compress the air within the crack. When
the wave retreats, the air in the crack expands quickly
causing a minor explosion. This process is repeated
continuously.
Attrition – material carried by the waves bump
Corrosion – this is the chemical action of the sea water.
The acids in the salt water slowly dissolve rocks on the
coast. Limestone and chalk are particularly prone to
this process.
KS4 Geography: Coasts
into each other and so are smoothed and
broken down into smaller particles.
Abrasion/Corrasion – This is the process by which
the coast is worn down by material carried by
the waves. Waves throw these particles against
the rock, sometimes at high velocity.
KS4 Geography: Coasts
Ways of protecting the coastline
Ways of protecting the coastline
Sea wall
Absorbs wave energy so the cliff foot
is protected from erosion.
Beach nourishment Extra sediment is
dumped on the beach to increase its size. A wider
beach will absorb more wave energy and protect cliffs.
Cliff drainage
Reduces the risk of weathering and
mass movement to protect the cliff
face from collapsing.
Rip rap Boulders dumped at the foot of the cliff allow
water through whilst dissipating wave energy.
KS4 Geography: Coasts
Gabions Wire boxes filled with stones are placed at the
cliff foot to dissipate wave energy.
KS4 Geography: Coasts
Ways of protecting the coastline
Hard engineering
Wooden groynes Wooden fences built out
into the sea. They stop longshore drift and build up
the beach. A wide beach absorbs more wave energy.
Hard engineering techniques aim to
stop coastal processes from occurring.
Managed retreat This involves breaching an existing
coastal defence, such as a sea wall, and allowing the
land behind to be flooded. This land is then left to be
colonised by saltmarsh vegetation. When established,
the vegetation disperses wave energy, reduces
erosion rates and provides new habitats.
KS4 Geography: Coasts
Examples of hard engineering
include:
• Sea wall
• Rip rap
• Gabions
• Groynes
KS4 Geography: Coasts
Soft engineering
Soft engineering methods try to work with
nature to protect the coast.
Examples of soft engineering
include:
• Managed retreat
• Beach nourishment
• Cliff drainage
KS4 Geography: Coasts
Landforms
Landforms created by erosion include headlands
and bays, caves, arches, stacks and stumps.
Landforms created by deposition include beaches,
spits, tombolos and bars.
KS4 Geography: Coasts
Headlands and bays
The formation of caves and arches
Headlands and bays are
formed when an area of
soft rock, such as clay, has
areas of harder rock either
side of it, such as chalk.
Caves
• Lines of weakness such as
faults occur in headlands.
• Abrasion and hydraulic
action erode the fault to
form a cave.
The soft rock is eroded
more quickly than the
surrounding hard rock,
which creates the bay
and headlands.
Arch
• A cave is widened
and deepened.
• The sea cuts through to
form an arch.
KS4 Geography: Coasts
KS4 Geography: Coasts
The formation of stacks and stumps
Landforms created by deposition
Stack
• The sea erodes the foot of an arch and widens it.
• The roof of the arch becomes too heavy
and collapses.
• Part of the former cliff is now isolated as a stack.
Beach – Beaches form in sheltered environments,
such as bays. When the swash is stronger than the
backwash, deposition occurs.
Stump
• Over time a stack is undercut and collapses.
• A stump is the remains of the eroded stack.
KS4 Geography: Coasts
Spit – A spit is an accumulation of sand with one
end attached to the land and the other reaching out
across an estuary or into the sea. They are formed
where a large amount of sediment is transported by
longshore drift, and the coastline suddenly changes
direction to leave a sheltered, shallow area of water.
KS4 Geography: Coasts
Landforms created by
deposition
Tombolo – a tombolo is a spit that connects an
island to the mainland.
Bars – if a spit joins one part of the mainland
to another it is called a bar.
Blank for your own notes
KS4 Geography: Coasts
KS4 Geography: Coasts