AGASSIZ: FIJI ISLANDS AlsD COEAL EEEFS. 7o 



correct in my interpretation of what I have observed ; information, in 

 fact, wliicli may be obtained as one steams along, without the trouble or 

 cost of boring. Should I be correct in my inference, I am inclined to 

 look upon the boring at Funafuti much in the same light, and to assume 

 that that island is also in an area of elevation, as well as others in tlie 

 EUice group, and that the great thickness of coral obtained was reached 

 in the base of an ancient limestone, and that the results obtained by the 

 boring there do not assist us in any way in coxToborating the theory of 

 subsidence as essential to the formation of atolls. 



The evidence which has been brought forward regarding the great 

 thickness of modern reefs, as postulated by Darwin, from that of the fos- 

 sil coral reefs existing during former geologicarperiods, seems to me to 

 he of little value. Langenbeck -^ and von Lendenfeld -^ have both urged 

 this point. The former lias given an excellent resume of the subject of 

 these ancient reefs, although he has no personal knowledge of recent 

 reefs. All that can be said at present is that these so called fossil 

 reefs are coralliferous limestones of great thickness, which first occur in 

 the Devonian ; they are little developed either in the Permian, or Trias, 

 or Lias. They are again well developed in the Jui-assic period, less so 

 in the Cretaceous, and increase in Tertiaiy times. That parts of some 

 of these coralliferous limestone masses represent reefs there can be little 

 doul;)t, vet the observations we made in Fiji regarding the coralliferous 

 elevated Tertiarv limestones, which have been considered as elevated 

 reefs of the present epoch, only show how guai'ded we should be in an 

 expression of opinion as to what constitutes a fossil reef, — I mean a 

 fossil fringing or barrier reef, or a fossil atoll, — when we are not able to 

 decide that point in the reefs of to-day, and when one set of observers 

 claims that the Tertiary elevated limestones represent elevated atolls, 

 while tlie other set clearly shows- that these elevated limestones have 

 played no part in the formation of tlie recent atoll, or barrier reef, but 

 have merely built up the substratum upon which the moderately thin 

 crust of recent reefs has established itself. 



Granting, even, as is very probable, that when these Tertiary lime- 

 stones were formed they were formed in great part by subsidence, 

 and in part by accretion from the carcasses of the invertebrates living 

 upon their sui'face, this would in no way help us to a satisfactory 



1 Langenbeck, R. : Die Theorien iiber die Entstehung der Koralleninsein und 

 Korallenriffe und ihre Bedeutung fiir Physische Fragen. Leipzig, Abschnitt IV. 



2 Nature, May, 1890, p. 29. See also the interesting note by von Fritsch. 

 quoted by Kramer, he. cit., p. 33. 



