Wave Erosion

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Wave Erosion
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Aim How do waves cause erosion?
I. Wave caused by wind
A. The size of a wave is determined by wind
speed, the length of time the wind blows in one
direction and the distance the wind has blown
across the water (fetch).
B. Wave characteristics

• Crest top of wave
• Trough bottom of wave
• Wavelength distance from one crest to the next
  crest
• Height vertical distance from the trough to the
  crest

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C. Wave motion
1. Water particles rise and fall in circular
paths with little forward movement until the wave
gets closer to the shore.
2. Surf foaming water resulting from water
breaking on the shore
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Wave Motion
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D. Wave erosion
1. Breaking storm waves may strike rock cliffs
with a force of thousands of kilograms per square
meter
a. May remove large boulders and wash away loose
sand and clay. b. Boulders fall and break up
other rocks that they hit
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2. Results of shoreline erosion

• Sea cliff
• Stack
• Sea cave
• arches

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Sea Arches
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Sea Stacks
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Sea Cliffs
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3. Water and sediments on a beach are moved by
swash, backwash, longshore currents, and rip
currents.
a. Swash motion of water up the beach
b. Backwash water that moves back down the
beach under the next wave. (strong backwash is
called an undertow).
c. Longshore current water that moves parallel
to the shore beyond the breakers
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d. Rip currents strong surface currents that
flow away from the beach.
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