184 R. A. Daly — Problems of the Pacific Islands. 



steamer anchored off a Pacific island, which characteristically 

 rises from deep water, like a pier. The commander of the 

 Coast Survey steamship "Blake" has shown that a depth of 

 12,000 feet is not too great for securely anchoring a vessel. 

 As already noted, continued observation of the Falcon and 

 other volcanic shoals of recent formation, through detailed 

 sounding, should afford direct information as to the speed of 

 marine abrasion in moderate depth. Such determinations 

 ought to control our ideas as to the efficiency of waves and 

 currents in making the great platforms and as to the position 

 of sea-level when they were made. 



5. Can one escape the conviction that there was some chill- 

 ing of Pacific waters during the Glacial period, with some 

 inhibition of coral growth? Systematic investigation of the 

 islands can hardly fail to illuminate this subject, which is 

 highly important in the field of pure biology as well. Closer 

 study of Hawaiian glaciation and paleontological work, such 

 as that indicating a decidedly cooler climate for Java in the 

 Glacial period, are needed. Other possible criteria for the 

 former chilling should be worked out and applied in the island 

 research. 



6. The independence of reef and platform in origin is 

 strongly suggested by the break of slope between the two, as 

 shown in the charts now published. Yet many profiles, care- 

 fully sounded across each of several reefs and on into its lagoon, 

 would have great value in making still more vivid this signifi- 

 cant feature. In the same way detailed profiles of coral knolls, 

 so common within the lagoons, should be plotted from sound- 

 ings, since they too bear on the origin of the platforms. 



More expressly referring to the reefs themselves are a host 

 of physical and biological problems, of which only a few can 

 be mentioned. 



1. Considering the obvious difficulty of the subject, new, 

 prolonged studies on the rate of coral growth are urgently 

 required. Yet more complex is the question as to the rates of 

 reef growth, for a reef is typically constituted of much material 

 other than coral skeletons. 



2. Thorough quantitative work on the proportions of coral 

 and non-coral components in the normal reef has still to be 

 done. 



3. Is Gardiner right in holding that reef corals do not 

 thrive in depths greater than 120 feet, because their chief food 

 is made up of green, chlorophyll-bearing algee ? Is light only 

 indirectly necessary to the polyps, since it is an indispensable 

 condition for the life of their plant food ? 



4. What are the physical conditions for vigorous growth of 

 nullipores and other important allies of corals in the work of 



