/•;. \Y . Skeats— The Coral-reef Problem 



valleys and embayed coasts are by Daly attributed to rise of 

 sea level and not to subsidence of tbe land. 



Davis, in common with others, admits some change of sea 

 level due to glaciation and subsequent melting of Polar ice caps, 

 but doubts the quantitative significance which Daly attributes 

 to it, and indeed, regards it as of minor importance. These 

 indirect methods of enquiry have assumed much of their 

 importance from the circumstance that the materials and con- 

 stitution of normal atolls are not commonly available for direct 

 examination except when subsequently elevated or explored 

 by boring. 



Some fifteen to eighteen years ago the writer, while a 

 demonstrator under the late Professor J. W. Judd at the Royal 

 College of Science, London, was concerned in the examination 

 of coral limestones from upraised coral islands* and also made a 

 large number of the analyses of the materials of the cores from 

 the borings into the atoll of Funafuti. For some years he was 

 handling the sliced cores of the latter bore and has examined 

 most of the rock sections so ably described by Professor Cullis 

 in the mineralogical part of the Funafuti report. f The writer's 

 familiarity with the bore cores from Funafuti and his experi- 

 ence with limestones from upraised coral islands constitute his 

 justification for contributing to the present discussion. The 

 significance of the evidence made available by the publication 

 of the very detailed and exhaustive examination of the Funa- 

 futi bores appears to have escaped many workers on coral reef 

 problems or to have been misunderstood. This no doubt is 

 partly to be attributed to the circumstance that the committee 

 responsible for the work consisted of adherents of diverse 

 views on atoll formation, and decided that the experts to whom 

 the material was submitted should publish descriptions of the 

 material but should draw no conclusions from the facts as to 

 the mode of formation of the atoll. The writer believes he is 

 correct in stating that these experts were unanimous in their 

 views that the published descriptions supported Darwin's sub- 

 sidence theory, and in fact were fairly susceptible of no other 

 known explanation. 



In this paper it is not proposed to discuss in detail the big 

 problems raised by Prof. Davis or by Prof. Daly with the 

 exception of three points raised by the latter, namely, the sub- 

 marine profile of Funafuti, Daly's and Von Lendenfeld's views 

 and diagrams of the development of coral atolls and the mech- 

 anism of the filling of " lagoon moats." 



The author is principally concerned that more serious con- 

 sideration should be accorded to the positive evidence provided 

 by the examination of the bore cores which is published in the 



*Skeats, Bull. Mus. Comp. Zool., Harvard, xlii, pp. 53-126, 1903. 

 f Funafuti report, Royal Society, London, 1904. 



