ATOLL AND REEF FORMATION 235 



on by no less than three successive" expeditions. The object 

 of the examination was the making of a bore through the 

 island and its basis in order to determine if the necessary 

 depth of coral reef, which a theory of subsidence demands, was 

 found to exist in reality. In the volume in which the results 

 of this successful boring are published (" Atoll of Funafuti," 

 Boy. Soc, 1904) the core obtained, to a depth of 1114^ feet, 

 is described in its entire length, and the conclusion appears 

 to be that the whole extent of the core had been formed at a 

 distance of no more than 50 fathoms from the surface, and 

 consists of a continuous formation of reef rock. Reef corals 

 were found as casts in the lower limits of the core, and if these 

 corals are in the position of their growth, then a gradual sub- 

 sidence must have taken place during the formation of the 

 atoll. On the other hand, to my mind, the description of the 

 core reads far more like a section of a talus bank, with surface 

 forms of corals and foraminiferse, piled in disorder as a debris 

 slope. Since the bore was driven on the extreme — windward 

 — edge of a reef some ten miles across, there is no reason why 

 this should not in fact be the talus slope of an originally 

 smaller reef, the primitive boundaries of which are to be found 

 somewhere nearer the middle of the present lagoon. If the 

 original submarine bank had grown seaward only half a mile 

 in all its long history, its talus bank would have been pierced 

 by the bore, and its condition would in all probability have 

 been just what is seen in the actual bore.* This is made easy 

 of understanding by means of a diagram drawn to scale. (See 

 Fig. 53, p. 153.) 



This objection is not urged in the spirit of destructive 

 criticism, for it seems to me that some atolls may have been 

 formed on subsiding bases : but to my mind it renders it quite 

 impossible to say that any process of subsidence caused the 

 development of this atoll of Funafuti. More recently Mr. 

 Hedley has shown — and here the evidence appears to be con- 

 clusive — that the Great Barrier Reef of Australia is the site 



* On this point see also Hedley, Natural Science, xii., March 1898, 

 p. 174. 



