69 



CHAPTEE III. 



FRINGING OR SHORE REEFS. 



Beefs of Mauritius — Shallow channel vjithin the reef — Its slow filling 

 up — Currents of water formed within it — Upraised reefs— Narrow 

 fringing -reefs in deep seas — Beefs on the coast of E. Africa and of 

 Brazil — Fringing-reefs in very shallow seas, round banks of sediment, 

 and on worn-down islands — Fringing-reefs affected by currents of the 

 sea — Coral coating bottom of the sea, but not forming reefs. 



Fringing-reefs, or, as they have been called by some 

 voyagers, shore-reefs, whether skirting an island or 

 part of a continent, at first appear to differ little from 

 barrier-reefs, .except that they are generally of less 

 breadth. As far as the superficies of the actual reef 

 is concerned, this is the case ; but the absence of an 

 interior deep-water channel, and the close relation in 

 their horizontal extension with the probable slope of the 

 adjoining land beneath the sea, present essential points 

 of difference. 



The reefs which fringe the island of Mauritius offer 

 a good example of this class. They extend round its 

 whole circumference, with the exception of two or 

 three parts l where the coast is almost precipitous, and 



1 This fact is stated on the authority of the Officier du Eoi, in his 

 extremely interesting ' Voyage a ITsle de France,' undertaker] in 1768. 

 According to Captain Carmichael (Hooker's Bot. Misc., vol. ii. p. 316), on 

 one part of the coast there is a space of sixteen miles without a reef. 



