Geological History, Features of Geomorphology
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Fig. 1.6 Continued
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characterized by abundant coral growth and fast calcification. This results
in the formation of impending "sill reefs" - steep reef terraces formed by
foliose or massive corals like Echinophyllia on Pacific atolls, or
Montastrea, Agaricia and Madracis on Caribbean reefs. In this zone an
abundant sessile fauna of sclerosponges, bryozoans, gorgonaceans, and
hydro ids flourishes.
d) Bu - Buttress zone, depth 20-Sm (see Fig. 2.1). The windward reef
slope is formed in this zone by spoors with grooves between them. The
spoors or buttresses are 3-S m high ridges descending down the slope and
are constructed by abundant coral populations, growing between the
grooves, through which sediment and rubble material are moving down
from the upper reef zones. The buttress zone is one of the most
important elements in the coral reef ecosystem. Dissipating wave energy,