growing reefs are mainly restricted to the west, or leeward coast where
a gently sloping shelf extends about 300 m seaward to a depth of 10 m.
Fringing reefs form on this, mainly around headlands, as narrow segments,
semi-circles or curved strips. They are generally poorly developed, consisting
of reef rock and coral debris covered with Lithothamnion and sparse
colonial growths o f Porites porites, P. astreoides, Siderastrea siderea
and Millepora alcicornis. At the edge of the shelf, the sea
floor falls regularly to about 20 m depth into a narrow trough paralleling
the shore. Seaward, a submerged but still slowly growing barrier reef,
12-20 m deep and up to 100 m wide, runs parallel to the coast, extending
from north to south and possibly connecting with a barrier reef along the
south coast. A second fossil submarine reefal ridge runs parallel with
this on the seaward side at 65-70 m depth.