THE GREAT ERUPTION OF SAKURA-JIMA IN 1914. 9 



It is contrary to modern views that here the volcano of 

 Sakura-jima and many others sit upon the compressed, wedged-in 

 bottom of a rift-valley instead of the loosened high edge of the same. 

 Such examples are, however, not wanting in fissure-eruptions and 

 effusions in Iceland. 



PBoI^Nor ^^) ^^^ passing, the writer may mention for the sake 



™îûKY?*^ of completeness the southern extension of the outcurve 

 of the Eyûkyû arc. Adhering still to the same principle, 

 we trace the trend of the ancient, green schistose Sambagawa- 

 Mikabu beds through a detached group of the Saki-jima Group 

 toward the stupendous diorite cliff of the Dome Cape of Taiwan 

 (Fig. 1). Just as ill the Kyùkyû arc, the fundamental structure 

 of Taiwan remains the same, being homoclinal and also dipping 

 westward. The same series in Taiwan, however, pursues a 

 southward course, curving inward and westward ; consequently, the 

 east side of the island corresponds to the inner zone, and indeed 

 a volcanic chain runs along the inner, east side. See Fig. 1. 



In short, the guide line of the southwest islands of the Japanese 

 territory describes an unbalanced sigmoidal course, the Byiikyii 

 curve faces its convex, and the Taiwan curve^' its concave side to- 



1) The geologic structure of Taiwan is unique. The festoon islands of Kastern Asia, as in 

 aU similar cases of cur\ilinear island chains elsewhere, face their convex side toward an open 

 ocean, while Taiwan alone (see Fig. 1) behaves contrariwise. The late von Richthof en in his 

 oft-cited Morphologische Studien aus Ostasien called our attention to this point, and said of this 

 island that it is geologically neutral, Avhile leaving the question open on the cause which produced 

 this peculiar geologic structure. The writer also believes that Taiwan is indeed a neutral region, 

 and has been at a standstill, while the Phihijpine and .Taiwanese islands disproportionately buhfed 

 out toward the western arm of the Pacific, which is a gigantic depression on the ancient 

 continental border of Eastern Asia, and which the writer habitually ciiUs the ' South Japan Sea.' 



As a result of a conference with ^Messrs. Yamané and Noda, of the Geological Survey, who 

 recently made journeys through South China, the writer is impressed with the idea that the 

 inclined tableland of Fo-lden, together ^^"ith the adjacent portions of Kwang-tung and Che-Mang, 

 conforms to the incurve of Taiwan, -with tilted edge this time toward the interior of China. This 

 is the all important tectonic line in southeastern China, which has hitherto escaped the 

 observation of geologists. 



