COASTAL DEPOSITIONAL FEATURES

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COASTAL DEPOSITIONAL FEATURES

• GEOL 1033

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DEPOSITIONAL COASTAL LANDFORMSare varied and
often associated with each other

• beaches
• sand bars
• sand spits
• tombolos
• beach ridges
• beach cusps
• cuspate forelands
• barrier islands
• coastal sand dunes
• washover fans
• salt marshes
• tidal flats
• lagoons and bays
• tidal deltas
• river deltas

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MAJOR OCEANIC MATERIAL INPUTS

• Input source input amount
• Rivers 84
• Glaciers 9
• Windblown dust 3
• Coastal erosion (higher than ave. locally) 1
• Volcanic debris lt1
• Groundwater flow lt2

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A well-defined, lobate sediment plume is seen
emerging from a river source on this stretch of
wave-dominated (beach-fronted) Atlantic
coastline. Currents are starting to carry some
of the sediment northward in the offshore
environment. Note the broad, well-"fed" beaches
in the direction of sediment transport and
narrower, retreated beaches in the opposite
direction. Typically, river input and cliff
erosion are the major sources of sediment for a
coastline (Space Shuttle, March 1994).
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WAVE-DOMINATED NILE DELTA
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Maps of some US barrier island coastlines
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Plum Island, Mass.

• Plum Island, northeastern Massachusetts, low
  altitude, oblique, aerial view of barrier island
  with beach-dune ridge showing washovers,
  vegetated backdunes, back-barrier marsh with
  tidal channels (16 July 1975).

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Sand Spits at the Down Drift ends of Barrier
Islands
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Beach ridges on a barrier island

• McLaughlin's Beach (southwest end of Ninety Mile
  Beach), Victoria, Australia Recent Low altitude,
  oblique, aerial view of low-angle truncation of
  multiple beach-dune ridges (chenier ridges).
  This once prograding coastline was retreating, at
  least locally when this picture was taken (1976).

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Development on a Barrier Island

• Ocean City, Maryland, U.S.A.
• Modern Beach island modification Ocean City, a
  developed barrier island. Host to 8 million
  visitors a year, this city (and others similarly
  situated) has no effective protection against
  flooding and damage from severe storms.

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