331 DEVIATIONS FROM NORMAL FORM. 



very remarkable in the space between 12° 20' and 

 11° 30', where we have Cape Grenville, Cockburn 

 Islands, and Sir C. Hardy's Islands, projecting 

 towards Raine's Islet opening, and Fair Cape and 

 Cape Weymouth, with Forbes Island and Quoin 

 Island, projecting towards Wreck Bay. Near Sir 

 Charles Hardy's Islands there is also a remarkable 

 narrow channel of deep water, between them and 

 the large Cockburn reef, in which there is a depth 

 of thirty fathoms, while on each side of it is either 

 a reef nearly dry at low water, or a depth not 

 exceeding ten fathoms. This channel is about 

 twenty miles long, rarely more than two miles broad, 

 and it runs in the same direction as the islands lie 

 off Cape Grenville, or about E.N.E., and points in 

 a straight line for Raine's Islet opening. 



The law which is found generally to prevail in 

 coral reefs, in all parts of the world, that the widest 

 openings or greatest breaks are on the leeward side, 

 or in the portions most sheltered from surf, is exem- 

 plified in the Great Detached reef, and in Raine's 

 Islet and Black Rock entrances, which are each 

 protected by reefs projecting out to windward of 

 them. 



The protection which coral reefs afford to coast 

 lines is also observable in the state of the bottom, 

 which, close in shore of the main land, consists of 

 the finest mud, while the coarse sand is accumulated 

 just inside and near to the outer reefs, where the 

 heavy surf is alone found, and in the breaks of 



