coastal processes writing 1
GEOL 103 Writing Assignment 7: Coastal Processes
Name _______________________ Lab section: Monday or Tuesday (circle one)
To be counted, must be turned in by Friday November 22.
1) Label the sketch below with:
wavelength wave height (amplitude) crest trough
Explain the orbits.
Orbits show the circular motion of water particles as a wave passes. The water particles themselves do
not move in the direction of the wave.
What happens to orbits when they encounter a shallowing sea floor near a beach?
Orbits flatten out, especially near the sea floor, as they interact with the bottom. Eventually the wave
becomes unstable and forms a breaking wave in the surf zone.
What happens to orbits during a storm? Orbits reach deeper, disturbing sediment on the sea floor that is not
disturbed during normal conditions. Storm wave base is deeper than normal wave base.
wavelength
wavelength
wave height
crest trough
2) What is fetch, as applied to waves? Why do the Great Lakes have noticeable waves, but smaller lakes do not?
Distance wind blows across a body of water. The greater the fetch, the greater the wave height. The Great
Lakes are large enough to have wind blow across them for a long distance, causing larger waves than
smaller lakes.
3) What happens to wave height, length, and velocity as they approach shore? Why do waves bend as they
approach shore?
Height increases. Length and velocity decreases.
Wave bend because they 1) usually approach beaches at an angle, and the part of the wave nearest shore
slows down more than parts farther offshore due to interaction with the bottom.
4) Sketch a) a summer beach, and b) a winter beach. What happens to beach sand during the winter and why?
What happens to beach sand in summer and why?
steeper water level less steep water level
sand stored
offshore in bars
sand stored
onshore
summer winter
Small summer waves push sand onto the beach, storing sand in a steeper beach front. Larger winter
storm waves pull sand offshore, storing it in sandbars.
