^ 4 — 



>of llie beauliful sceuery of Tahiti, so well calleil , » ibe Queeii of Islan<ls." 

 » We caiinot supoose these encirclin"; reefs are baicd on au external crater 

 » for ihe ceotral inass sometinies consists of priiiiary rock, or on any accu- 

 »inulalion of sediinenlnry de'posits , for the reefs follow indifTerently the 

 »island ilself, or its submarine prolongation. Of this laller case tbere is 

 »a grand instance in New Caledonia , where the reefs extend no less tlian 

 »140 miles beyond the island." 



Tliroiiglioiit tliis palaver, Mr. Dau\vi:v conslantly assumcs 

 tliat lagoon reefs and islands may be produced by one and 

 the same cause, liis subsidence theory to wit, wliilst it is 

 irapossible for him, or any one for hiin , to shew even a pro- 

 bability in support of tliat assumption. The central islands 

 which are now standing within encircling reefs, wcre most pro- 

 bably originated as foUows. When the submarine volcanic (or 

 as it may be naraed lavatic) protuberance, had ascended so near 

 to the surface of the ocean that it burst open, as afore said , the 

 sea then tumbling in solidified the central body of the liquid 

 rock, to some depth downwards. The exterior shell of the mass 

 liaving been previously solidified, by exposure to the rcfrigerating 

 action of the ocean water, this central body in the proccss of 

 solidifying shrunk, and thereby became a cone or cylinder, 

 scparated from the external shell, after which, the pressure 

 from' below being still continued, or at any subsequent time 

 renewed, that central raass woiüd be raised upwards (as a plug 

 is forced out of a jar, by internal pressure), so bccoming an 

 island , and probably by successive rccurrences of the submarine 

 action elevated high above the ocean level, the exterior shell, 

 remaining all the time at the elevation it had attained when 

 the top burst open; meanwhile the action of wind and rain etc. 

 on the si des of the elevated mass would reduce the surface to 

 mould and sand, at the same time carrying that downAvards, 

 pavtly to forin the alluvial belt around the island , and partly into 

 the spacc betwccn it and the top of the shell, or crater w^all, 

 wliilst the coral building polypi were fixing themselves on the 

 top of that wall. and thereby raising upon it a coralline reef, 

 or as it may be termcd a copiug of coral. 



As for not beiug able to suppose , that any of these reefs are 



