Volcano Ôshima, Idzu. 4«> 



(2) The northicestern skirt of the somma is extensively de- 

 veloi^ed with very gentle slope. This is attributable partly to the 

 extrusion of the lavas from flank openings, the more striking of 

 which are indicated by the scoria? accumulations as Atago'\ Kaza- 

 machi^ etc. (p. 20), and partly to the existence of small igneous 

 bodies (p. 3S) along the western half of the northern coast of the 

 present Ôshima, which must have protected the new deposition from 

 marine action, thus affording conditions specially favourable for the 

 extensive development of the skirt. 



(3) The southeastern part of the island is also extensively 

 developed. This may be due to its having been the scene of fre- 

 quent volcanic actions (pp. 25-26). 



(4) The eastern slope of the mountain is abnormal, the gentle 

 slope continuing from the summit to half way and Ijecoming sud- 

 denly steep on approaching the sea shore. The profile of the 

 island cut in an E.-W. direction through the centre shows a 

 striking asymmetric form. 



This asymmetric form has been noticed l3y previous writers, 

 and various views have been suggested to explain it. YAMASAKf ^ 

 tried to explain the abnormal feature of the eastern slope by sup- 

 posing the existence of some older volcanic todies in that part 

 (p. 7), while ÔHASHI denied the presence of old volcanic bodies^^ 

 and attributed the asymmetric form to the tilting of the grouncT'^ 

 (p. 10). These are, however, hypotheses for which there is no 

 direct evidence, while the latter may now l^e proved impossible. 



s! ?K%ort on'lhf?olcano ôshin^a" l^eport B.U., Invest. Co.., Ko. 9. 1896 (in 

 Jap.naiese).^^ the Geology of Volcano ôsLimn." Mer. Geol Soc. Tôkrô, Voi. XVI., pp. 5-22-524, 



1909 (in Japanese). ^ , „_^^, -o iqi7 li-n 



5) "On the Asymmetrical Form of Osliima." »it?., ^ol. XXTV., p. -2. IUI/ (m. 



Japanese). 



