Harbors can be natural or artificial. An artificial harbor has deliberately constructed breakwaters, sea walls, or jettys, or otherwise, they could have been constructed by dredging, and these require maintenance by further periodic dredging. An example of the artificial harbor is Long Beach Harbor, California, which was an array of salt marshes and tidal flats too shallow for modern merchant ships before it was first dredged in the early 20th century.<ref>http://geology.campus.ad.csulb.edu/people/bperry/geology303/geol303chapter8.html</ref>
Harbors and ports are often confused with each other. A port is a facility for loading and unloading vessels; ports are usually located in harbors.
Intro Artificial harbors Natural harbors Ice-free harbors Important harbors See also Notes External links
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