lithosphere - coastal

hydraulic action

pounding waves compress trapped air in the rocks creating an explosive blast which weakens and loosens rock fragments

abrasion

rock fragments thrown against headlands create a sandblasting action wearing away the rock

wave cut platform

• weaknesses such as joints, faults or cracks in cliffs are undercut by erosion to form a wave cut notch

• as this notch is enlarged cliff face becomes more unstable by the weight of the overhang can no longer be supported

• cliff eventually collapses and retreats

• waves and sea currents clear the debris at the base of the cliff exposing a gently sloping wave cut platform

• platform is abraded by rock materials with rock pool and pot holes forming which is evident at low tide

headland and bay

• formed by differential erosion where softer less resistent rocks erode more quickly than harder resistent rocks

• a headland is an area of hard rock which juts out into the sea and a bay is a sheltered area of softer rock between headlands

• often form in areas with a discordant coast line where alternate bands of rock are formed at right angles to the coast

• constructive waves build a small beach in the sheltered bay between the headlands

caves

• rocks contain weak points that are more easily eroded

• overtime lines of weakness are enlarged and develop into small sea caves

• in some cases a blowhole can form in the roof of a cave

• a compressed air is pushed away upwards by waves causes verticle erosion which is enlarged by the cave

arch

• rocks contain weak points that are more easily eroded

• overtime lines of weakness are enlarged and develop into a small sea cave

• in some cases a blowhole can form in the roof of a cave and there may be erosion on both sides of the headland due to wave refraction until eventually the sea cuts through the back walls of the cave forming an arch

stack

• rocks contain weak points that are more easily eroded

• overtime lines of weakness are enlarged and develop into small sea caves

• in some cases a blowhole can form in the roof of a cave and there may be erosion on both sides of the headland due to wave refraction until eventually the sea cuts through the back walls of the cave forming an arch

• continued erosion enlarges the arch

• eventually the arch collapses due to gravity to form a stack

coastal process of deposition

• formed by the process of longshore drift

• swash is where waves driven by prevailing winds push material up the beach at an angle

• the returning back wash is dragged back by gravity down the beach at right angles

sand spit

• spits form when there is a change in direction on a coastline

• allowing a sheltered area for deposition

• material slowly builds up to appear above the water

• the spit develops as long as the supply of deposits is greater than the amount of erosion

• the shape can become hooked or curved at the end in response to change in wind direction

sand bar

• bars form where there is a change of direction on a coastline

• allowing a sheltered area for deposition'

• material slowly builds up to appear above thee water

• the bar develops aslong as the supply of deposits is greater than the amount of erosion

• if a spit reaches the other side of a bay then a sand bar is created