CHAPTER III. 



FRINGING OR SHORE-REEFS, 



Reefs of Mauritius. — Shallow channel within the reef. — Its slow filling 

 up. — Currents of water formed within it. — Upraised reefs. — Narrozu 



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

 Brazil. — Fringing-reefs in very shallozv 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, might at first be thought to differ little, except 

 in generally being of less breadth, from barrier-reefs. 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 beneath the sea of the adjoining land, 

 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, 1 

 where the coast is almost precipitous, and where, if as is 



• 1 This fact is stated on the authority of the Ofhcier du Roi, in 

 his extremely interesting Voyage a Vlsle de France, undertaken in 

 1768. According to Captain Carmichael (Hooker's Bot. Misc., vol. 

 ii. p. 316), on one part of the coast there is a space for sixteen miles 

 without a reef. * 



