GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 309 



Caledonian barrier is due to the cut and fill process of marine 

 planation at and below sea level during the cliffing of tbe 

 promontories and to the sediment deposited in the sea, derived 

 through the erosion of mature valleys, I can not say with cer- 

 tainty, but that so much material deposited in the sea would 

 under the influence of waves and currents form a submarine plain 

 is a warranted deduction; and as the barrier reef is crossed by 

 gaps and is discontinuous at both the southeast and northwest ends, 

 the deduction seems safe that it is superposed on a submerged plat- 

 form of antecedent existence. 



FIJI ISLANDS. 



That the barrier reefs off the Fiji Islands have developed during 

 or after submergence of their basements is obvious from an inspec- 

 tion of the charts to anyone familiar with the physiography of shore 

 lines. The numerous reproductions of British Admiralty charts in 

 A. Agassiz's volume on the Fiji Islands^ is valuable and convenient 

 for such a cartographic study. That the indentations of the shore line 

 in the Fijis are due to the drowning of the lower parts of subaerially 

 formed valleys has been pointed out by many geologists, the first 

 of whom appears to have been Dana, who says:^ 



There is, further, not merely probable but positive evidence of subsidence in the 

 deep coast indentations of the high islands within the great barriers. The long points 

 and deep fiordlike bays are such as exist only where a land, after having been deeply 

 gouged by erosion, has become half submerged. The author was led to appreciate 

 this evidence when on the ascent of Mount Aoraion Tahiti, in September of 1839. 

 Sunk to any level above that of five hundred feet the erosion valleys of Tahiti would 

 become deep bays, and above that of one thousand feet, fiordlike bays, with the 

 ridges spreading in the water like spider's legs; and this is a common feature of the 

 islands and islets within the lagoons of barrier islands. The evidence of subsidence 

 admits of no doubt. It makes the conclusion from the Gambler group positive; 

 and equally so that for Raiatea and Bolabola represented on the charts in Darwin's 

 •'■' Coral Islands; ' ' the Exploring Isles and others of the Fiji group; and that for islands, 

 great and small, in the Louisade Archipelago and in other similar groups over the 

 ocean. 



This statement was misinterpreted by Davis as being confirmation 

 of Darwin's theory of coral reefs,^ which, as is more than once pointed 

 out in the present paper (see especially p. 249), carries with sub- 

 mergence an hypothesis of platform building. Evidence of sub- 

 sidence does not prove that the flat lying between a barrier reef 

 and the shore has been formed by infilling behind the barrier. 



Daly made a definite statement in 1910 in a Hst of "maximum 

 depths recorded for the drowned portion of these valleys," in which 



1 Agassiz, Alexander, The Islands and Coral Reefs of Fiji, Mus. Comp. Zool. Bull., vol. 33, pp. 167, 112 



plates, 1899. 



2 Dana, J. D., Corals and coral islands, ed. 3, pp. 273, 274, 1890. 



3 Davis, AV. M., Dana's confirmatioa of Darwin's theory of coral reefs, Amer. Joum. Sci., ser. 4, vol. 35, 

 pp. 173-188, Feb. 1913. 



