Vol. XLIII, Art. 6. — S. Tsuboi; 



the island and made some geological observations. They pointed 

 out that the harbour of Habu'^ (3e), which was thought by the 

 earMer writers to be the crater of an old volcanic body, might be 

 an explosion crater formed at the foot of the main cone of Ôshima ; 

 and that Hikubo'^ (3e), a depression lying to the west of Habu 

 and hemmed in by a horse- shoe shaped wall, might be also of 

 like origin. Tliey further attributed the formation of a great gap 

 on the northeastern side of the ring- wall of the somma to an 

 explosive action. 



Cape Chigasaki'^ (la), an elevated spot at the northwestern 

 end of the island, was noticed by them for its peculiarity and was 

 considered to be either a parasitic cone or an old volcanic body. 



FüKUCHi^-' visited 

 the island again in 

 1905, when a destruc- 

 tive earthquake occur- 

 red there. A geologic 

 sketch map presented 

 by him with his report 

 shows the existence 

 of old volcanic bodies 

 lying to the north and 

 to the cast of the 

 island (Fig. 4). 



Fig. 4. FuKXJCHi's geologio sketch map of Ôshima. [,. 1 QO? SeIII 



Nakamura, Torahiko Terada, and Den'ichiko Ishitani'^ studied the 



W^ Old volcanic body 



^^ Somma 



[y.^l Parnsitic cones 



[ I Central cone 



O Emption-crater 



(p^ Exjilosion-c rater 



^ Fiimarole 



1) iè/f- 2) t^,-K- 3) ^^Ws ox f^fWr 



4) "Geological Observation on the Eixrthqiiake of Ôshima in lUOFi," Be'pùit Earlhq. Invest. 

 ■Com., ÎSO. 53, p. 87, 1900 (in Japanese). 



£>) " The Volcano of Ôshima, its Past and Pre.sent," Proceedlnjs >tf the Tokyo Mathematico- 

 IP/.ysical Sodety. Vol. IV., p. 2)î, 1908; Jour, deo/jr. Tokyo, Vol. XX., Nos. 238-239, pp. 682 & 

 786, 1908 (in Japanese). 



