Physical Geology
Shorelines
- shape of a wave:
crest
trough
wavelength
height
period
- orbital motion of the wave dies out at a depth of about 1/2 the wavelength. This depth is known as the wave base.
- wavelength decreases as shoreline approaches, due to frictional drag, and the height increases.
- sand is moved by longshore drift
- can pile up sand along jetties, and erode sand in open areas.
- Erosion along coasts results from the abrasive force of water and sand.
wave-cut cliffs
sea caves, arches, and stacks
- Deposition: Sediment deposited in areas of low wave energy.
- wave refraction around a headlands area will erode the headland, and deposit sediment as the waves refract and disperse.
beach
spit
- areas where longshore drift has extended into bays
tombolos
- beach grows and connects with an offshore island
barrier islands
- offshore islands of sediment parallel to the shore, usually cut by tidal currents.
- Tidal waves:
- waves produced by water displacement through earthquakes, underwater volcanoes, and submarine landslides.
- travels at high speed, has long wavelength.
- almost unnoticable on the open ocean
- only a problem when the wave encounters shallower water and the wave base hits the floor, increasing the heigth of the wave dramatically.
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