162 B. A. Daly— Problems' of the Pacific Islands. 



extent of that fragmentation, its geological date or dates, its 

 relation to the question of land bridges and the distribution of 

 organisms, and its relation to volcanism in the Pacific are all 

 matters of primary importance. 



Connected therewith is the problem lately suggested by 

 MolengraafPs and Brouwer's remarkable discoveries of typical 

 radiolarian sediments, charged with manganese nodules, in the 

 mountains of Borneo, Timor, and Roti.* This kind of sedi- 

 ment seems to be formed only in sea water more than 10,000 

 feet deep ; yet Molengraaff has found it in mountains at 4000 

 feet above sea, and covering thousands of square miles in 

 Borneo alone. Are there similar evidences of tremendous 

 upheaval in Oceania ? How far are the heights and hollows of 

 the western Pacific due to warping of the earth's crust ? How 

 far to block-faulting? 



One of the grandest, as well as clearest, proofs of recent 

 crustal warping is due to Professor Lawson's pioneer studies 

 of San Clemente and Santa Catalina, two Pacific islands of 

 continental affinities. San Clemente has been recently uplifted 

 about 1400 feet and, as shown in the Coast Survey chart, has 

 a series of strand-lines engraved on it by the waves. Santa 

 Catalina, a neighbor to San Clemente, has contemporaneously 

 sunk. It lacks elevated sea-cliffs and, on the other hand, its 

 shore-line has the appearance of having been drowned by sub- 

 sidence. Professor Lawson's studies, like the later ones by 

 Dr. "W. S. Tangier Smith, have assuredly whetted the appetite 

 of geologists for more information about the other islands of 

 the Californian coast. 



Volcanic Islajids. 



Let us now glance at the volcanic archipelagoes. Excluding 

 ]STew Guinea and its satellites, but including the Hawaiian, 

 Galapagos, and Juan Fernandez groups, Oceania has 345 

 islands which are definitely described in the scientific literature 

 as wholly or largely volcanic in origin. Probably the whole 

 number showing volcanic rock above sea-level is at least twice 

 as great. How many other volcanic masses exist as " banks " 

 or as basements completely veneered by coral limestone is 

 obviously unknown, but their number doubtless runs into the 

 hundreds. 



Petrography. — Among the ascertained volcanic islands, 

 only 152 have yet afforded any petrographic data ; of those not 

 a half dozen have been examined with the thoroughness 

 demanded by modern geologists. In order to summarize the 

 little now known about the island petrography, and to suggest 



• *G. A. F. Molengraaff, Proc. Kon. Akad. Weten. Amsterdam, 1909, p. 141 ; 

 Deel 23, 1915, p. 1058 ; and Deel 24, 1915, p. 415. 



