394 FUNAFUTI: THE STORY OF A CORAL ATOLL. 



"barrier" reefs. In these, as we might expect, the form of the reef is 

 only remotely related to the contour of the inclosed island, the valleys 

 of which present that fiord-like character so suggestive of sunken land. 

 The last stage is that of the atoll itself. 



The excellence of Darwin's theory lies in this, that it explains all the 

 essential features of an atoll on one simple assumption. It is incon- 

 sistent with no known fact, and as additional discoveries have been 

 made it has not required to be supplemented by fresh hypotheses. It 

 is not like a Gothic structure, supported by flying buttresses and other 

 tours de force, but rather resembles some noble Italian tower, which 

 rises from its base, straight, simple, and self-sufficing. It was no 

 sooner given to the world than it commanded almost universal assent. 

 Nevertheless, it has never been without a rival. Even before 

 Darwin published his celebrated work Ainsworth l had suggested a 

 different explanation. He rightly pointed out that Quoy and Gaimard 



had not established a limit 

 a.nsworth f or a n reef-building organ- 



isms, and that although cer- 

 tain corals, such as they 

 had observed, might be 

 restricted to shallow waters, 

 there might yet be others 

 capable of flourishing at 

 greater depths. If so, these 

 deep-water organisms might be engaged in laying the foundations of 

 an atoll on which the shallower water forms might erect the super- 

 structure (fig. 3). This suggestion seems to have fallen stillborn, but 

 the notion of "laying the foundation" of an atoll was not destined to 

 perish ; it has been revived of late years by Sir John Murray, who, 

 guided by his observations made when on board the Challenger, was 

 led to suppose that the submerged summits of deeply sunken islands 

 might be raised to within the limits of 25 fathoms, not by the upward 

 growth of corals but by the incessant downward rain of minute organ- 

 isms from the surface of the sea. The same agencies which were sup- 

 posed to be spreading out a layer of chalky mud, or ooze, over the 

 abyssal floor of the ocean were also imagined as engaged in piling a 

 Pelion of mud on every submarine' Ossa (fig. 4). 



The publication of Sir John Murray's views was followed by a long 

 controversy, in which Darwin's theory was subjected to a most search- 

 ing criticism. An impartial summary of the arguments arrayed on 

 both sides of the question is given by Professor Bonney in the last 

 edition of Darwin's " Coral Beefs," and the general subject is treated 



' G. W. Ainsworth. "Analysis of a voyage to the Pacific and Behring's Straits to 

 cooperate with the polar expedition, performed in H. M. ship Blossom, under com- 

 mand of Capt. F. W. Beechey, R. N., in the years 1825, 1828." — Geog. Jour., Vol. I, 

 1831. 



Fig. 3. 



