Yul. XLIII., All. ('. — a. T.snboi: 



of tlîo island, the whole history of the \olcano may bo divided' 

 into three periods. (1) The first period is that represented by the 

 crater of Habu^^ (3e) which he considered to have been submarine 

 till the vent was completely congealed. (2) The second period is- 

 marked by the extinction of the Habu crater and the birth of a 

 hypothetical volcano at the northern part of the present Oslnma. 

 The supposed remains of this volcano ho considered to have been 

 completely buried later. He assumed the existence of this northern 

 volcanic body to explain the abnormal topography of the island, 

 writing : — 



" Die Convexitat fies iiürdlicheii Al)liauges lässt sich gewiss. 



nicht besser erklären, als durch Amiahine einer filtereu hcsoiidereu Enip- 



tionsaxe für diesen Theil des Berges. ..." 



Fig. 3. N.\t'makn's klenl profile of Ôshima (N.-S.). 



a Ihe crater of the first i.eiiol. h The cmter of the second period. 



(■■•■ The crater of the third peiiod. 



(3) The third period was represented by the present crater of 

 Mihara." 



In 1886, Shôgo Nishiyama'^ wrote a brief note on the topo- 

 grapliy of Oshima and the state of the crater at that time ; but 

 the geology of the island was not studied further after Naumann's 

 visit until 1895, when Naomas\ Yamasaki'^ made his trip. 



He noticed the abnormal complex topography of the eastern 



1) }&''?■ A.n inlet at the S.S.E. end of the island. 



;;) "Explanatory Text to the Geologic Sheet of Idzu" 1886 {in Japane.se). 

 4) "Report on the Volcano Ôshima," Beport Eirthr/. Invest. Com., No. '.), pp. 3.3-53, 1838- 

 i^n Japanese). 



