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Ocean and Coastal Systems
Barrier island coasts are those paralleled by deposits of
sand separated from land by a lagoon. There is some controversy over how
barrier island coasts form. They begin as offshore bars of submerged
sediment that migrate landward unless stabilized. Barrier islands
are often cut by tidal inlets, openings that allow water to move
landward and seaward with the tides. Barrier islands border the Atlantic coastal plain of North America.
Figure 21.21 Birdfoot or Balize delta of the
Mississippi River
Courtesy USGS Source:
Geomophology From Space
Delta coasts are those formed by the deposition of sediment at the mouth of a
river that enters the ocean. Deposition is caused by the rapid
decrease in water velocity as it enters the ocean. Sand and silt are
the first to deposit while the mixing of fresh and salt water cause
clay particles to bind together forming larger particles that settle
to the bottom.
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