COASTLINES

Key Terms

Swash is the movement of a wave up the beach, from the sea.
The Backwash is the movement of a wave back down a beach
Where the swash is the stronger part of the wave, the wave is constructive and builds up a beach.
Where the beach is broken down by a stronger backwash, the waves are similarly said to be destructive.
The movement of waves at an angle up the beach and then straight down is called Longshore Drift; this process moves sand along the coastline.

Coastal Landforms

A spit is where longshore drift moves a line of sand out to sea, creating a long
When a sand-bank joins an island to the mainland, it is called a Tombolo.

Coastal Defences

Groynes are (usually) wooden barriers that go acorss a beach, preventing longshore drift.
Rocks can be dumped across the beach to absorb the force of the waves. This "rip-rap" or "rock armour" is very effective but expensive and unsightly.
Gabions are another way of using rocks to absorb wave-force; stones are places in metal cages, which are then piled up to absorb the wave-force.
Perhaps the "ultimate" coastal defence is a simple one; a curved wall to reflect the wave's energy. Sea walls are expensive and unsightly, and require maintenance, but are long-lasting and tough protection for coastal towns.

Formation of Coastal Landforms

Stacks

When waves erode a cliff or headland, they cut out notches at the level of the sea.
The notches can then erode further into the cliff, forming a cave.
The cave can sometimes erode a hole up through the rock, creating a "blowhole" out of which water will spray at high tide.
Where two caves meet, creating a hole right through a headland, the waves create a wave-cut arch.
Over time, the arch may well collapse, leaving a tall stack of rock at the end of the headland.
The stack, battered by the waves, will in time collapse itself, leaving a stump which then further erodes and is lost forever.

Longshore Drift

As the swash of a wave goes up a beach, it often hits the land at an angle. However, the water comes back down the beach straight; thus, there is a zig-zag movement of sand along the beach.

Case Studies

Facts and Figures; Holderness Coastline

Background;

Fastest eroding coast in Europe
Many villages/towns under threat

Places to remember;

Flamborough Head is not affected as the rock there is harder
The resort of Hornsea has groynes to protect its beach from longshore drift
Great Cowden is just down from Hornsea, and due to Hornsea's groynes it has lost its beach extremely fast; the cliffs are being eroded very quickly.
At Withernsea a sea wall has been built to protect the town.
Spurn Head used to have a small village based around the coastguards and the lighthouse. However, it has been abandoned as the spit it was built on has eroded in the middle, cuttiong off all road access and making it very hard for the residents.

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