Wave Erosion
Geo 12
Name______________
Indicate whether each of the following statements is true or false. If false explain why the statement is
false.
1. Wave base is the depth of the deepest trough of a wave.
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2. Waves derive their energy from tidal forces.
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3. Water molecules in a wave remain essentially stationary, and just move in
a circular path.
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4. The vertical distance between a wave’s crest and its trough is termed wave height.
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5. Wave period refers to the horizontal distance between one wave crest
and the successive wave crests.
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6. Waves are affected by the bottom of the ocean at a depth of one-half
of the wavelength.
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7. Waves transfer energy and move abundant volumes of water.
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8. a) At what depth would a scuba diver have to dive to avoid waves with a wavelength of four meters?
b) At what depth would a wave cause turbulence to ocean floor sediments if the wave was 20 meters
long? At what depth would these waves break?
c) You observe that waves are travelling at a velocity of 32 metres/second. You observe eight waves in
one minute. At what depth would these begin to feel bottom?
d) You observe that the surf zone begins several metres offshore and you are considering walking out
to the surf zone. The wavelength of the waves is 60 metres. Would it be safe to walk to the beginning
of the surf zone? Why or why not?
9. A beach changes character with the seasons. As shown in the figures below.
The winter beach profile is characterized by a narrower beach and an offshore sand bar. The lower
picture is of the summer beach profile and is characterized by a wider beach and the absence of an
offshore sand bar. Discuss the role of wave base in forming both a winter and a summer profile.
10. The picture below depicts the wave direction along the beach where you own a cottage.
a) On the diagram, indicate (with an arrow) the direction of the longshore current.
b) On the diagram, draw the best location of a groin to prevent the erosion of your beach.
c) How would the construction of this groin affect the nature of your neighbour’s beach?