3 - Coastal Landscapes Flashcards
COASTAL: HYDRAULIC ACTION
the sheer force of waves crashing against the shore and cliffs. The power of the waves forces air into cracks, compresses it and blows the rock apart as the pressure is released.
COASTAL: ABRASION
the process of rocks and pebbles carried by the waves wearing away rocks as they are thrown against cliffs.
COASTAL: SOLUTION
when chemicals in the seawater dissolve minerals in the rocks, causing them to break up.
COASTAL: ATTRITION
when rocks and pebbles carried by the waves smash into each other, wearing each other away and gradually becoming smaller, rounder and smoother.
WHAT IS LONGSHORE DRIFT?
- A pebble or sand particle moves from point A to B, carried by the swash up the beach, the angle determined by the wave and wind direction.
- It is then pulled down the beach from B to C, carried by gravity and the wave’s backwash.
- This process is repeated over and over again, and the particle moves along the shoreline - this process is called longshore drift.
WHEN DO CLIFFS FORM?
Form where there is harder more resistant rock such as Moray sandstone or limestone.
HOW DOES A WAVE-CUT NOTCH DEVELOP?
Waves erode the rock between high and low tide marks through hydraulic action and abrasion.
This forms a wave-cut notch at the base of the cliff where wave erosion is greatest.
WHAT HAPPENS TO A WAVE-CUT NOTCH OVERTIME?
As the notch develops over time, it undercuts the cliff which eventually collapses into the sea.
As the cliff retreats it leaves behind a wave-cut platform.
WHERE DO HEADLANDS AND BAYS FORM?
Form when alternating bands of hard and soft rock are found at the coast e.g. moray sandstone or limestone.
WHAT IS DIFFERENTIAL EROSION?
Softer rock erodes more quickly than harder rock so differential erosion occurs.
Soft rock retreats faster to form sheltered bays which often have beaches, e.g. Findhorn Bay.
The harder rock is more resistant to erosion and juts out into the sea to form exposed headlands, e.g. Burghead
WHEN DO CAVES. ARCHES, STACKS FORM?
Form when waves erode lines of weakness along a headland by hydraulic action and abrasion.
HOW DO CAVES, ARCHES, STACKS DEVELOP OVER TIME?
Overtime, the lines of weakness are enlarged and develop into small sea caves eg Sculptors Cave, Moray
The caves are deepened and widened on both sides of the headland until they eventually form an arch.
The rock at the top of the arch becomes unsupported as the arch is enlarged, eventually collapsing to form a stack.
WHERE DO SAND SPITS FORM?
Spits form where the coastline changes direction and longshore drift continues to move material along the beach.
HOW DO SPITS DEVELOP OVER TIME?
Over time the level of the sand deposited will build-up until it is above sea level.
The spit cannot develop right across the bay as a river’s estuary prevents the build-up of sand.
Sand spits often have a curved or hooked end. This is created when secondary wind and wave direction causes waves to strike from a different direction.
WHERE DO SAND BARS FORM?
A sand bar is formed when there is a gap (such as a bay) in the coastland with water in it.
Where there is no river estuary, beach material can be deposited faster than it is eroded.
