modified by j.shannon the coast: erosion. the coast: beaches and shoreline processes
TRANSCRIPT
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MODIFIED BY J.SHANNON
The Coast: Erosion
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The Coast: Beaches and Shoreline Processes
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Coast and Shore Coast: Area of contact between land and sea—Extend
inland until meets a different geographical setting
Shoreline: Precise boundary where water meets adjacent dry land
Shoreline
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Waves: transport energy by motion—ultimate source of wave energy is the sun
Longshore current: Current that parallels shoreline developed by waves coming in at an angle to shore.
Shaping of Shorelines
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Longshore Currents• Parallel motion of water along shoreline
• Caused by wave refraction(bending)• Causes zigzag motion of water in surf zone
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Waves are dominant mechanism in coastal erosion—Water forced into cracks in rock at high pressures
Coastal erosion
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Coastal erosionWave energy is focused on prominent points that jut
out into deep water
• attack the sides of points and form sea caves, sea arches, and sea stacks by undercutting them
Sea stack with sea arch in it
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• Marine erosion is most rapid on high-energy coasts, areas battered by large waves. (erosionional shore)
• Low-energy coasts are infrequently attacked by large waves. (deposional shore)
Shorelines Can Be Straightened by Erosion (Wave Energy)
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Erosional Shores-Features
• Protruding bits of land called headlands absorb much wave energy.
• Wave cut cliffs and sea caves are other features carved out by wave activity.
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Erosional Shores
• Sea arches form where sea caves in headlands erode all the way through.
• Sea stacks form when the tops of sea arches erode away completely.
• Bedrock uplift generates a marine terrace.
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