THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Akt. XXXII. — Pleistocene Glaciation and the Coral Reef 

 Prohlem ; by Reginald A. Daly. 



Introduction. — During the last thirty years, most of the 

 active students of atolls and barrier reefs have tended to 

 oppose the Darwin-Dana hypothesis of extensive and pro- 

 longed crustal subsidence in the Pacific and Indian ocean 

 basins. The borings at Funafuti do not seem to have proved 

 the hypothesis even in the case of this one atoll. In Hinde's 

 detailed description of the cores we read that, from the top 

 down to the 150-foot level their material is chiefly coral. Of 

 the remainder of the boring, 663 feet are noted as principally 

 composed of detrital and foraminiferal matter ; 279 feet carry 

 small masses of coral, but the relative proportion of coral rock, 

 as opposed to detrital and foraminiferal mattei- (here also 

 abundant), is not stated ; while only 22 feet, in all, of the core 

 below the ISO-foot level is described as originally solid coral 

 rock.* These figures and, yet more clearly, the thoroughly 

 particularized text of the report, suggest that the 1,114-foot 

 boring penetrated — first, a true reef extending little deeper than 

 the bathymetric limit of reef -building corals ; and then, a much 

 thicker talus deposit containing blocks of massive coral. At 

 several of the deeper levels the corals found are stated to have 

 been " probably in the position of growth," but no discussion 

 of this principal conclusion is contained in the report. Though 

 most of the material constituting a typical reef is not solid coral 

 rock, the percentage of non-detrital coral rock in the Funafuti 

 main boring appears to be much too low to prove the Darwin- 

 Dana hypothesis. 



On the other hand. Semper, Murray, Alexander Agassiz, and 

 others have long contended that coral reefs have been formed 



* See Section xi of report on " The Atoll of Funafuti," London, 1904. 



Am. Jour. Sci. — Fourth Series, Vol. XXX, No. 179. — November, 1910. 

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