274 TOILERS IN THE SEA. 



subside. Now, as the island sinks down, either 

 a few feet at a time, or quite insensibly, we may 

 safely infer, from what is known of the conditions 

 favourable to the growth of coral, that the living 

 masses, bathed by the surf on the margin of the 

 reef, will soon regain the surface. The water, however, 

 will encroach little by little on the shore, the island 

 becoming lower and smaller, and the space between 

 the inner edge of the reef and the beach proportion- 



54. 



A. A. Outer edges of fringing reef. 



B. B. Shores of fringed island. 



Upper horizontal line showing sea level after a period of 

 subsidence. 



ally broader. A section of the reef and island in 

 this state, after a subsidence of several hundred feet, 

 is given by the dotted lines. Coral islets are sup- 

 posed to have formed on the reef, and a ship is 

 anchored in the lagoon channel. This channel will 

 be more or less deep, according to the rate of 

 subsidence, to the amount of sediment accumulated 

 in it, and to the growth of the delicately-branched 

 corals which can live there. The section, in this 

 state, resembles in every respect one drawn through 



