AGASSIZ : BERMUDAS. 243 



of coralline . . . detached and broken," is derived from the rehandling 

 of the ledges of seolian rock of the former sea-shore. The corals now 

 growing play an infinitesimal part in the forming of the sand dunes 

 which "stand on the eminences which to-day are the Bermudas." His 

 description would apply to the original reefs from which the Bermudian 

 hills were formed, but is scarcely applicable to the work doing in our 

 day. 



Heilpriu, after quoting Dana's description of the reef of an atoll, 

 finds it largely applicable to the condition of the Bermudas, an opinion 

 to which exception must be taken. From what has been said it will 

 be seen that the Bermudian coral reefs have little if anything in com- 

 mon with the coral reefs of an atoll. Certainly no more erroneous state- 

 ment could be made than that " the more seemingly favored patches are 

 the creations of the surf themselves." The Bermudian reef corals are, 

 like the Bahama reefs, submerged, rarely come to the surface, and have 

 not supplied any considerable part of the material which has gone to 

 build up an extent of land either in the Bahamas or the Bermudas. In 

 the Bahamas the corals nourish most profusely in depths of from five 

 to twelve fathoms; at the Bermudas six to seven is their limit, and 

 those on the sea face of the ledges do not seem any more abundant 

 than those on the edges of the flats. I was not able in the several 

 sections I made across the sea faces of the southern reef to find 

 the unbounded profusion of coral growth which Heilprin observed. 

 In fact no one has better shown than he that the coral reefs which 

 now encircle, the Bermudas have had no share whatever in their 

 formation, and I fail to see how the fact that subsidence has given 

 to these islands their outline of to-day has any bearing upon the theory 

 of the formation of coral atolls by subsidence. Any land surface ex- 

 posed to the action of the inroads of the sea owing to its subsidence 

 would have been eroded to some extent according to the nature of the 

 rocks composing it. The subsequent formation of a thin veneer of coral 

 reefs upon its sunken ledges would not have any bearing on the theory 

 of the formation of thick masses of limestone by subsidence. It mav be 

 interesting, in this connection, to refer to Heilprin's statements "that 

 the present form of the Bermuda Islands bears no relation to the ring of 

 an atoll," and that " the existence of an atoll is not demonstrable." 1 



I fully concur in what he says regarding the subsidence which 

 followed the elevation of the islands to their greatest height. Heilprin 

 was impressed by the absence of loose boulders of rock (coral?). 



1 Bermudas, p. 4(3. 



