152 ART. 3. — B. KOTÔ : 



Part III. Petrography.^^ 



§ I. The Lavas of the Pre-historic Cones. 

 A. The Lavas of K-ita-daké. 



à) Topographic Features.— As it has been stated already (p. 35), 

 Kita-daké or the ' north cone,' which carries the apical crater of 

 Mihachi, 1,037 ??2., constitutes alone the main structure of Sakura- 

 jima, making up the highest cone and occupying nearly the whole 

 base of the island. See Geologic Map. At later times several 

 lateral flows and subaërial talus, together with pluvial fans, only 

 slightly contributed to the peripheral expansion which is at present 

 about 4 km. in basal diameters. That the Kita-dakè lava is the 

 principal building material can be confidently affirmed by tracing 

 the occurrences of the same rock nearly through all parts of the 

 island, although later flows hide and obscure exposures, especially 

 on the eastern slope. 



•NoETHEEN Northern Slope. — A complete exposure (Geologic 



Map, n) from top to shore can be traced on the northern slope, 

 terminating at the point of Wari-ishi-Saki. It is the Uno-hami^^ 

 ßoiü. There is a lava-shelf or terrace at an altitude of from 200 

 to 300 m. on the slope, formed by stemming of subsequent flows 

 of magma. 



The adjacent eastern area is now under the lava sheet of 

 17 79-' 80, while the western is overlaid by the lava apron {nk) of 

 Kabano.'^ On the eastern skirt of the latter there are two narrow 



1) The characterization of rocks under the present heading is merely of preUminary 

 qualitative nature, detailed quantitative study being out of question at the i^resent moment. 



2) ^/±. 



3) See posteu, p. 158. 



