coral reef (redirected from Deltaic reef)

coral reef

Ridge or hummock formed in shallow ocean areas from the external skeletons of corals. The skeleton consists of calcium carbonate (CaCO₃), or limestone. A coral reef may grow into a permanent coral island, or it may take one of four principal forms. Fringing reefs consist of a flat reef area around a nonreef island. Barrier reefs may lie a mile or more offshore, separated from the landmass by a lagoon or channel. Atolls are circular reefs without a central landmass. Patch reefs have irregular tablelike or pinnacle features. Smaller patches occur inside atoll lagoons; larger patches occur as isolated parts of any of the other three reef categories, and they sometimes occur completely separate from other kinds of reefs.

---

coral reef [′kär·əl ‚rēf]

(geology)

A ridge or mass of limestone built up of detrital material deposited around a framework of skeletal remains of mollusks, colonial coral, and massive calcareous algae.