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Navassa Island: A Photographic Tour (1998 - 1999)

Navassa Island Home
Explore Navassa
take a Tour:
geology | biology | history
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Navassa map
Navassa Location Map
Explore Navassa - Geology
A Former Coral Atoll

  upper terrace
upper terrace
Ancient coral reef sediments that have been raised above sea level by vertical movements of the earth's crust underlie Navassa. Navassa may have formed as a small coral atoll, but at the close of the Miocene Period about 5 million years ago, these reefs began to emerge. Emergence resulted in the alteration of calcium carbonate sediments (aragonite) to calcium-magnesium carbonate rock (dolomite), the formation of a terrace around the island, and the beginnings of chemical weathering and cave formation.

  oolitic phosphate
oolitic phosphate
About two million years ago phosphate-rich sediment was deposited on the island, perhaps guano that was greatly altered to form the mineral phosphate deposit now found on the surface. The oolitic phosphate forms a thin veneer overlying and filling karst holes in the dolomite.

Geology - Photo Index
Sea Floor
    sea floor
    sea floor
    sculpted rock
    irregular floor
    eroded boulder
    rock terrace
    upper terrace
    upper terrace
    terrace karst
    terrace karst
    terrace karst
    lower terrace
    terrace slope
    sea cliffs
    sea cliffs
    cliff face
    cliff face detail
  Vertical Cave
    cave entrance
    climbing down
  Vertical Cave
    vertical cave
  Cliff Cave
    down the cliff
    cave entrance
    in the cave
    cave wall
    cave water
    cave pool
  Undersea Cave
    submarine cave
    phosphate sand
    fractured rock
    rock samples
    solution crack
Fossil Corals
    fossil coral
    fossil coral
    fossil coral
    fossil coral
    eroded coast
    solution hole
    solution holes

Coastal and Marine Geology Program > St. Petersburg Coastal and Marine Science Center > Navassa Island > Geology Tour

U.S. Department of the Interior, U.S. Geological Survey, Coastal and Marine Geology Program
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Page Content Last Modified: August 2000