xxi 







13^^^^ Couthouy on Coral Formations 



above water, principally loose rubble and sand, the whole 

 about a league in circuit, and situated twentyfive or thirty 

 leagues east of the Samoas — so recent was the formation that 

 besides the main entrance into the lagoon on the leeward side, 

 there were several small channels, others partially bridged 

 over, and some closed only at one extremity. Not a particle 

 of vegetation had yet made its appearance, elsewhere than on 

 the most elevated portion of one sandy knoll, which a solitary 

 shrub (a Pisonia, if I recollect right,) had begun to clothe 

 with verdure. In the shallow lagoon, it would seem as if 

 there had not elapsed since its formation a period sufficient for 

 the coral to have grown in any quantity, as only a few small 

 clusters were seen here and there, the bottom being almost 

 entirely a fine white coral sand, such as is common on the 

 beaches of those islands having shore reefs, and quite destitute 

 of the smooth, calcareous paste, deposited in most lagoons. 

 Scattered over this sand, were a number of boulders of vol- 

 canic rock, some of them so heavy that two men could not 

 raise them from the bottom, and precisely similar in appear- 

 ance and mineral structure to that constituting the mass of 

 the neighboring groups of Samoa and Tahiti. A specimen 

 weighing about twenty pounds was picked up in four feet 

 of water, among small rolled blocks of coral conglome- 

 rate. This circumstance appears to aflford conclusive evidence 

 that the main rock of the submerged island must be at no 

 great depth below the sandy bottom of the lagoon, since it 

 was evidently not long since acted upon by the surf, the only 

 imaginable power which could have placed these boulders in 

 their present situation. At the same time, that the islets 

 are now slowly emerging, is indicated by the whole surface 

 of the reef, which is so for elevated, that the corals have 

 nearly ceased to flourish, and are for the most part covered 

 with an incrustation of lime, which promises ere long to unite 

 the whole into an uniform consolidated mass. 



That there was an interval of quiescence between the last 

 epoch of subsidence and that of re-elevation, is, I think, 

 proved not only by the construction of the marginal project- 

 ing shelf, which has evidently once existed on the upper 



