16 Vol. XLIir., Art. 6. - S. Tsiiboi : 



of the magma. The surface of the lava is often scoriaceous. 

 Some of the scoriaceous Japilh may have originated from the doagh 

 in the crater ; but another origin is also i^robable. It is conceivable 

 that as the lava flowed out its surface consolidated while the interior 

 was still in the molten state, so that when the molten pieces were 

 ejected they broke the sarficial crust of the lava, — hence the 

 formation of scoriaö. Scoriae considered to have been formed in 

 this way were often observed, being associated with the lavas or 

 accumulating on them as small spatter cones. Examples of such 

 accumulation of scoriae are seen at Kagamihata^^ (Ic) and at 

 Akahage'^ (lb). 



In short, the somma consists of many lavas and éjecta, the 

 result of repeated volcanic actions, which accumulated in alter- 

 nating layers. The eflect of these and later ejections is, that the 

 surface of the ground is so entirely covered that it is impossible to 

 estimate the structure of the core of tlio volcano and the dis- 

 tribution of each lava flow. 



Steep Slope along the East Coast. 



A remarkable feature of the island is a belt of steep slope, 

 about 40' in inclination, along the east cOast running in the direc- 

 tion from north to south (Fig. 5). On examining this part it 

 became clear that it does not represent the original slope, since 

 the lavas and éjecta layers are cut by it, but the geologic explana- 

 tion for this peculiar feature could not be found except by in- 

 ferences based on its topography. 



Ohashi'^-* considered this steep slope to be the remains of the 

 old sea cliff formed by marine abrasion. This explanation, how- 

 ever, does not seem to agree with some of the observed facts : 

 1) m^ 2) ^^ 



3) •• On the G-eology of Volcano Osliima," Jour. (Je^l. Soc. Tokyo, Vol. XVI., 1933 (in Japanese). 



