MATIINE BOTAITT. 101 



little into account, as it did the encircling reefs that sur- 

 round the lofty mountainous islands. 



Charles Darwin was the first to find the key to all those 

 geological riddles, by deducing the formation of the varying 

 Coral-reefs from the oscillating condition of the bed of the 

 sea, and its periodical elevations and depressions. 



Just as it is now undoubtedly proved, that some portions 

 of terra firma are continually rising (Scandinavia, Chili), 

 while others are sinking (Dalmatia, Greenland), there are 

 also rising and sinking regions in the Ocean. Among the 

 latter, for instance, is that space, 4,000 miles long and 600 

 broad, on which the Society Islands and the Lower Archi- 

 pelago culminate, the Coral Sea, the long chain of the Mal- 

 dives, Laccadives and Chayos Atolls. If, then, we fix our 

 attention on any one Coral-reef island in these slowly-sink- 

 ing regions, we find that, while it sinks, the equally sinking 

 Coral-reef is raised, or at any rate kept in equilibrium by 

 the new perpendicular erections of the Corallines, which try 

 to reach the surface. But the Corals lying near the open 

 sea find there better nourishment than those pointing to 

 land ; the former grow quickly, while the latter pine away, 

 and thus, with time, a reef is formed surrounding the island 

 at a considerable distance, between which and the coast the 

 sea is frequently found so deep that large ships can anchor 

 comfortably in this basin, as in a harbour. 



At length a period arrives when, by continual sinking, 

 the central island entirely disappears beneath the waves, 

 and the Atoll, or product of the Zoophytes, which labour 

 against the sinking process, is alone left. 



Hence, wherever low lagoon islands are now visible, once 

 lofty lands rose from the sea, whose existence would be for- 

 gotten did not the Coral erections remain in evidence. 



Prom the present size of the reefs it is calculated that the 

 plateau which was lost in this way from the Pacific covered 

 at least 2,000 square miles ; and, as there may have been 

 lands whose sinking proceeded too rapidly for the Corals to 



