Fig. 6.61. (A) Air photograph of the Columbus barrier reef, off the Yucatan peninsula, Belize. Open sea
to the right, tidal channel cross-cuts reef flat in the foreground, back-reef lagoon to the left. (Courtesy of
E. Purdy.) (B) Illustration of the physiography and facies of a modern barrier reef. Note that the steep slope
of a modern fore-reef is often a drowned Pleistocene sea cliff.