S. Powers — Volcanic Domes in the Pacific. 267 



feet and 100 feet deep exists on the summit. As a Japanese 

 painter who lived from 1765 to 1842 showed only Ko-Usu in 

 a sketch of the mountain, there is a slight possibility that O-Usu 

 rose during historic time. 



Kaimondahe. At the southern extremity of Japan in the line 

 of volcanoes including Aso, Kirishima, and Sakurajima is the 

 quiescent or extinct volcano Ivaimondake, 3,030 feet in height. 

 Friedlaender 9 has described the volcano as consisting of an ash 

 cone rising to a height of about 2,200 feet where there is a 

 crater wall, but the former crater is filled with an andesitic 

 dome surmounted by a flat depression but not a crater. The 

 dome is composed of very rough lava and it evidently repre- 

 sents such a dome as that on Tarumai. The last outbreak of 

 the mountain was in 1615, and the last important eruption 

 was in 885 A. D. At both these times ash was thrown out, 

 but at the former eruption a summit glow was seen, suggesting 

 that the dome appeared at that time. 



Sambondahe. About 100 miles south of the volcano Oshima 

 (Vries Island) and 23 miles southwest of the island Miyake 

 is a small group of rocks called Sambondake. The two larger 

 masses are described as being composed of andesite, with the 

 structure of dikes, 10 but the photograph of one of the masses 

 (see fig. 5) shows that it strongly resembles in appearance the 

 Mont Pelee spine. 



ChoJcai-San. The volcano Chokai-San, in Ugo province, 

 northern Japan, has. been active seven times since 810 T3. C, 

 and ten days after the last eruption (1800-1), according to 

 B. Koto, 11 a cone was raised on the east side of the summit 

 crater, very much like the Tarumai dome. 



Kilauea. Several times during the recorded history of 

 Kilauea there have been uplifts of portions of the floor of the 

 Kilauean sink surrounding the crater Halemaumau or of 

 debris within the crater and once a dome formed of the con- 

 solidated surface of the lava lake was raised over Halemaumau. 



In 1848 the first dome was formed. During the previous 

 two years there had been an active lava lake in Halemaumau 

 2000 feet in diameter, the surface of which became crusted 



"Peterm. Mitth., vol. lviii (1), pp. 309-12, 1912. 



10 1. Friedlaender, Mitt. Ges. Natur- und Volkerkunde Ostasiens, vol. xii, 

 Tokyo, 1909. 



11 On the volcanoes of Japan, Jour. Geol. Soc. of Tokyo, vol. xxiii, p. 9, 

 1916. Professor Koto also mentions that Ma-yama. west of Kampu-San, 

 northern Japan, is. according to tradition, a "puffed-up dome" (p. 9). 

 Under the head of "Tholoide," Professor Koto classes those volcanoes 

 which merely have a rounded form as well as those which are "volcanic 

 domes" in the sense used in this paper. 



Am. Jour. Sci. — Fourth Series, Vol. XLU, No. 249. — September, 1916. 

 18 



