30 AlîT. 3. — B. KOTO : 



the bay. They are buoyed up in different degrees or, in other 

 words, depressed in altitude with reference to the neighboring 

 plateau after the manner of the formation of a plateau. Volcanoes 

 are said to appear in diffuse manner in such a geologic pattern 

 of great magnitude (p. 20). 



YÉNO-SHIMA 6) Yeno-shdia^^ (PL XII. Fig. 1, and Geologic Map). 

 — In passing, it is to be noted that the islet Yéno-shima, lying 

 3 kiu. to the south of the defunct strait of Seto, is built up of 

 uniformly gray compact trachyandesite.'^ PI. XVI. Fig. 1. It is 

 simply a detached erosion remnant of the basal effusive of the 

 neighboring plateau formation, and in no way connected with any 

 lavas of Sakura-jima. 

 SüBCETJsT YiQ j^Q^ a]3]3roach the question as to the foundation 



OF Sakuka- ^ ^ ^ •' 



"^^ of Sakura-jima. From what is said in the foregoing, 



the basement bed seems in all probability the same complex that 

 makes up the four block-islands (1—3), and also the one that 

 builds up the plateau-land of southern Kyûshû. As Sakura-jima 

 is an island volcano, and is still young and not yet dissected, no 

 opportunities are yet given to get insight into the inner structure 

 of the volcano, and we have simply to conjecture the foundation 

 in the realm of imagination. 



A unique specimen of recent éjecta was given the writer by 

 Assistant Professor Kanai, of Kagoshima. It is a fritted 

 granite.'^^ As granite -batholiths intruding the Mesozoic slate for- 

 mation appear in Prov. Osumi, both may occur underneath the 

 foundation ; but no slate has hitherto been discovered among 

 recent éjecta except small fragments in trass.^^ The members of 



1) ir / â 



2) It is composed of plagioflase, orthoelase and hyperstliene in a crystalline gronndmass 

 of ragged prismoids of angite, plagioclase-latlis and magnetite crystals, ■\\ith trace of globulitic 

 and sanidinc -cement. 



3) See ' Ejected Blocks of Biotite-graiiite " in Petrograpliical Part. See VI. XXIII. Figs. 1 and 3. 



