THE GEEAT ERUPTION OF SAKURA-JIMA IN 1914. 155 



the north cone. All the I'ecent writers on Sakura-jima take it for 

 a parasitic cone, simply from its outer form. Tt is built up of 

 massive rock, which is of the saine land as that of the north cone. 

 Until this monadnock-like mass is convincingly proved to bo a 

 real parasite, the writer will relegate Hikino-hira to a part of an 

 ancient lava-flow, which was greatly disrupted by explosions of 

 old date in the neighborhood, so as to give the outward look of a 

 steep dome or tholoide. 



Southern Side. — A small elevation, 10 o m. high, near the defunct 

 strait of Séto, raised its head on shore fi'om below the ancient 

 lava of the south cone or Moyé-daké. The writer passed over the 

 edge of it and made a collection of the rock in January, 1913. 

 This Akashi- Gongen hill and the whole adjacent tract are over- 

 flooded by the recent lava and no trace of this "103 m. hill " 

 can be seen now on the surface, except a slight elevation in the 

 middle of it, indicating by the petrified cataract of recent lava 

 the site of this buried hill. About the origin of the hill, we find 

 no clue as to whether it is a margin of the North Cone or one 

 of its parasites. (Geologic Map, PL VIII. Figs. 2-3, PI. IX. Figs. 2-3.) 



Eastern Side. — A knob of Gongén-yama (340 m.) on the 

 eastern slope and the Sono-yama (Maru-tsuka or the ' round 

 mound,' 79 m.) on the northeastern shore are the geologic islands 

 of the Kita-daké lava or its parasitic cones left uncovered by 

 later flows. 



b) Pétrographie Characters.— The Kita-daké lava (PI. XVI. 

 Figs. 5 and 6) on the north side, a typical hypersthene-andesiteP 

 is the oldest and the most widely distributed rock of the island. 

 It is a light-colored, salic type, which rather resembles the Diluvial 



1) As it contains sanidine in the forms of plienocrysts and the rind aronnd plagioclase, it 

 may in future investigations turn out to be a hypersthene-latite or pyroxene-canLaUte. 



