P. A. Daly — Problems of the Pacific Islands. 173 



crown laid on a plateau, the surface of which is about 300 feet 

 below sea-level. In fact, multitudes of soundings have sug- 

 gested independent origins for the Pacific reefs and their 

 respective platforms. Further study at critical localities can- 

 not fail to throw light on this fundamental problem in topog- 

 raphy. 



Besides that principal query regarding Darwin's theory, 

 there are many others calling for active research on the reefs 

 and islands of the Great Ocean. 



1. According to Darwin's diagram above described, a bore- 

 hole, put down on the main reef of an atoll, should pass 

 through many hundreds of feet of material characteristic of a 

 massive reef. Such was the conception of the committee of 

 the Royal Society of London, which therefore sunk an 1100- 



Fig. 12. 



Fig. 12. Diagrammatic section showing the great amount of a reef's cen- 

 trifugal displacement which is necessary if the reef continued growth dur- 

 ing the subsidence of a normal volcanic island (vertically lined), and if the 

 "moat" were always filled with detritus so as to show depths no greater 

 than those of actual lagoons. In order to match actual conditions (flat 

 lagoon floors) the subsidence is assumed to proceed at a diminishing rate, 

 The line 1-2-3 is drawn too straight to match exactly the actual conditions, 

 but this arbitrary drafting does not essentially affect the usefulness of the 

 diagram. 



foot boring on the main reef of Funafuti atoll in the Ellice 

 group. Figure 11 is a chart and section of this atoll. The 

 section runs from northwest to southeast and is about nine 

 miles long. Now the log of the boring (made at the point 

 " B ") and the drill-core itself both seem to show that reef 

 material in situ ceases at the depth of about 150 feet. Beyond 

 that depth the drill passed through limestone which probably 

 represents more or less altered reef-talus, mixed with pelagic 

 shells. 



This result suggests the necessity of revising the usual state- 

 ment of the subsidence theory, if it is to explain Funafuti. 

 During the time required for the filling of the " moat," so that 

 the lagoon floor shall have its observed flatness and small depth 

 below sea-level, the reef should have grown far out on its own 

 talus, as indicated in the accompanying diagram (fig. 12). It 



