26 PROFESSOR W. J. SOLLAS. 



In this connection a quotation from Darwin may be apposite; he says* — " I have 

 referred to these possibihties merely to sliow how difficult it must ever be to judge 

 whether low coral formations have reallv l)een raised to a heio-ht of oidv two or three 

 feet, as Dana believes to have been the case witli several groups of atolls. 'J'o me 

 it seems more probable that all tlie al)ove-mentioned appearances merely indicate 

 tliat the atolls in question have long remained at the same level." If, however, 

 the conclusion arrived at by so excellent an observer as Professor Dana should 

 hereafter be confirmed, the question Avill arise, seeing how immense an area has 

 been thus affected, whether those jjeolo^ists are not riuht who believe that tlie 

 level of the oceAu is subject to secular changes from astronomical causes.!" 



A possible cause affecting some of the superficial features of the atoll may l)e 

 Ijriefly noticed. We have already seen that both our borings revealed for a considerable 

 distance downwards the existence of loose unconsolidated sand and coral debris, 

 and it is not a little remarkable that material so little ao-o-reo-ated should be able to 

 sustain itself in slopes of as much as 80'', such as occur between 3G and 129 fathoms 

 on the flanks of Funafuti. The i)Ossibility of submarine slips naturally suggests 

 itself, and a giving way of the reef, such as M'ould precede a fall, seems to be indicated 

 by a long continuous crack, which I observed traversing the hard seaward platform of 

 Funafuti islet for a distance of about a hundred yards, and in a direction parallel to 

 the coast. It is sharply cut and very narrow, never attaining, so fav as I remember, 

 a width of q\iite an inch. Darwin, however, has an account of others still wider 

 which are met witli in the Caroline Islands, his words are| "on Oulleay Atoll, . . . , 

 Admiral Llttke informs me tliat he ol)served several straio-ht fissures about a foot in 



* ' Conil liecfs,' p. 17;], 3rJ edition. 



t If the four stages, -which Ave have suggested, reall}^ did occur in the history of Funafuti, they might 

 very well be correlated with such movements of tlie ocean level as we should have expected on a priori 

 grounds to have occurred in tropical regions during the Pleistocene period. The accumulation of ice 

 al)out the polar regions during the glacial episode woTild seem almost necessarily to have brought about a 

 lowering of the sea-level in the tropics, and if it did we might distinguish four different levels as having 

 existed in these regions during Pleistocene times ; they Avould have been as follows : — (n) Pre-glacial 

 period, sea-level relatively higher; (//) glacial period, sea-level relatively lower; (r) genial period, sc.i- 

 level relatively higher ; ('/) jiresent period, sea-level relatively lower. The existence of a genial period 

 separating the glacial from our own times is indicated l)y the marine faunas of post-glacial deposits found 

 both in the Mediterranean basin and off our own shores. It will be seen that a close parallelism may be 

 drawn l)etween the four periods of sea-level as indicated by the atoll and as deduced from changes of 

 climate ; but this parallelism depends on the nature of the pinnacles of the glacis ; if the summits of these 

 should be found to consist not of corals in tlie position of growth, Imt simply of coral breccia, then the 

 supposed parallelism will disappear, and we shall haAe to conclude either tliat the Taiisale period corre- 

 sponds to the last genial episode which has affected our planet — and in this there would appear to lie 

 nothing improbable; or that the atoll affords no evidence either for or against the doctrine of the 

 association of changes of ocean level with those of teirestrial climate; it wouhl then follow that those 

 changes of level which v/e have described must be explained in some other way, and most likely l)}^ move 

 ments of the atoll itself. 



+ Ojj. nV., p. 132. 



