The results of work on reefs on Mah_e, Seychelles and Pleistocene limestones on Aldabra are briefly presented. These are used in discussion to highlight problems of reef description and illustrate the author's views on reef structure.

Reefs are presented as growing by a series of discrete increments controlled by sea level changes. This interpretation suggests that they are bedded structures with recent growth and deposition forming a thin veneer on a reef morphology which was already broadly defined.