VAST AMOUNT OF SUBSIDENCE, 281 



ly slow. This conclusion is probably the most im- 

 portant one which can be deduced from the study 

 of coral formations, and it is one which it is diffi- 

 cult to imagine how otherwise could ever have 

 been arrived at. Nor can I quite pass over the 

 probability of the former existence of large archi- 

 pelagoes of lofty islands, where now only rings of 

 coral-rock scarcely break the open expanse of the 

 sea, throwing some light on the distribution of the 

 inhabitants of the other high islands, now left stand- 

 ing so immensely remote from each other in the 

 midst of the great oceans. The reef-constructing 

 corals have indeed reared and preserved wonder- 

 ful memorials, of the subterranean oscillations of 

 level ; we see in each barrier-reef a proof that the 

 land has there subsided, and in each atoll a monu- 

 ment over an island now lost. We may thus, like 

 unto a geologist who had lived his ten thousand 

 years and kept a record of the passing changes, 

 gain some insight into the great system by which 

 the surface of this globe has been broken up, and 

 land and water interchanged. 



CHAPTER IX. 



Mauritius, beautiful Appearance of— Great crateriform Ring of 

 Mountains— Hindoos— St. Helena— History of the Changes in 

 the Vegetation— Cause of the Extinction of Land-shells — As- 

 cension—Variation in the imported Rats — Volcanic Bombs — 

 Beds of Infusoria— Bahia— Brazil— Splendour of tropical Scen- 

 ery— Pernambuco—Smgular Reef— Slavery— Return to Eng- 

 land — Retrospect on our Voyage. 



MAURITIUS TO ENGLAND. 



April 29th. — In the morning we passed round 



the northern end of Mauritius, or the Isle of 



France. From this point of view the aspect of 



the island equalled the expectations raised by the 



A2 



