Anchialine pool Archipelago Atoll Avulsion Ayre Barrier island Bay Baymouth bar Bight Bodden Brackish marsh Cape Channel Cliff Coast Coastal plain Coastal waterfall Continental margin Continental shelf Coral reef Cove Dune cliff-top Estuary Firth Fjard Fjord Förde Freshwater marsh Fundus Gat Geo Gulf Gut Headland Inlet Intertidal wetland Island Islet Isthmus Lagoon Machair Marine terrace Mega delta Mouth bar Mudflat Natural arch Peninsula Reef Regressive delta Ria River delta Salt marsh Shoal Shore Skerry Sound Spit Stack Strait Strand plain Submarine canyon Tidal island Tidal marsh Tide pool Tied island Tombolo Windwatt

Ancient reefs buried within stratigraphic sections are of considerable interest to geologists because they provide paleo-environmental information about the location in Earth's history. In addition, reef structures within a sequence of sedimentary rocks provide a discontinuity which may serve as a trap or conduit for fossil fuels or mineralizing fluids to form petroleum or ore deposits.

Although there are no active reef shark fisheries in the US Pacific, the reef sharks' disappearance could be caused by recreational fishing or illegal shark finning, which, combined, kill 26 million to 73 million sharks each year. Another possible explanation is that the reef sharks are starving. Their food sources, including coral reef fishes, are decreasing in number because of habitat destruction and human exploitation, and could be taking the sharks with them.


These biotic reef types take on additional names depending upon how the reef lies in relation to the land, if any. Reef types include fringing reef, barrier reefs, as well as atolls. A fringing reef is a reef that is attached to an island. A barrier reef forms a calcareous barrier around an island resulting in a lagoon between the shore and the reef. An atoll is a ring reef with no land present. The reef front (ocean side) is a high energy locale whereas the internal lagoon will be at a lower energy with fine grained sediments.
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