摘要：Revision: Action of Ice Definitions Coast: The strip of land where it meets the sea Coastline: The margin of land. The limit to which wave action takes place. Shore: The strip of land lying between the high and low water levels. Shoreline: The limit of the shore. The line where the shore and the water meet. Beach: A shore covered by a deposit of sand and/or pebbles. Factors Determining the Nature of Coasts Wave action Tidal currents Nature of the
Revision: Action of Ice
Definitions
Coast: The strip of land where it meets the sea
Coastline: The margin of land. The limit to which wave action takes place.
Shore: The strip of land lying between the high and low water levels.
Shoreline: The limit of the shore. The line where the shore and the water meet.
Beach: A shore covered by a deposit of sand and/or pebbles.
Factors Determining the Nature of Coasts
Wave action
Tidal currents
Nature of the rocks forming the coast
Height of the coast
Nature of the climate
Formation of Waves
Wind blows over the sea surface.
The surface of the sea exerts frictional drag on the lower layer of the wind.
The top layer (with the least drag) moves faster than the lower layer and hence tumbles over it.
This causes a circular motion of wind energy that acts on the sea to create waves.
Wave Erosion
Wave erosion like river erosion involves 4 processes:
Abrasion/Corrosion: The wearing away of the sides and the bed of a river by the impact of the load.
Hydraulic Action: Erosion by the force of moving water.
Attrition: The breaking down of the load by particles hitting against each other.
Solution/Corrosion: When minerals dissolve in water.
Features Produced by Wave Erosion
A notch is cut by waves at high tide level and developed further.
As this notch is developed, a cliff is formed.
The cliff steepens as weathering attacks the base further.
As the cliff retreats, the rock debris is swept by the backwash creating a wave-cut platform.
Some of the debris collects along the seaward edge of the wave-cut platform forming and off-shore terrace.
Caves, Geos, Arches and Stacks
Holes in the cliff face are enlarged by wave action
A tunnel like opening called a cave is formed.
The cave may develop further forming a long narrow inlet known as a geo.
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