96 S. SEKIYA AND Y. KIKUCHL 



ceous deposit« and sheets of volcanic rock, forming the basis of an 



elevated area known as the Aizu Plateau, which includes the 



districts of Yama, Aizu, Kawanuma and Onuma, in Iwashiro, its 



average height exceeding 500 in. above the sea-level, This plateau 



is surrounded on all sides by mountains of volcanic origin. On its 



southwest border stand the extinct volcanic peaks of Hakase-yama, 



Mikagura-dake &c, and on the south the conspicuosly Hat-topped 



Nunobiki-yama, formed of volcanic sheets. Among these mountains 



are found numerous hotsprings, more than 30 of which have been 



counted. 



The streams which rise in the surrounding mountains discharge 



into a depression on the south side of Bandai, there forming the Lake 

 Inawashiro, which is one of the largest in Japan. This lake, the 

 surface of which is 496 m. above the sea-level, is not a true crater-lake 

 as is sometimes supposed. Its principal feeder was the river Nagase, 

 flowing from the northern part of Bandai. The upper course of this 

 river was. however, entirely stopped by the falling débris during the 

 recent eruption, and the lake is now supplied mainly by its tributary, 

 Sukawa, flowing from Azuma-san. The lake discharges northwest- 

 ward, at the village of Tonokuchi, by a stream which flows through 

 the Aizu Plateau under the name of Xippashi-gawa for about 11) 

 kilometres, then joining the Aka-gawa. The latter stream collects all 

 the waters of the Aizu Plateau, and finally runs into the Japan Sea 

 near the port of Niigata. Recently another outlet was made on the 

 eastern side of the lake, by means of a canal for irrigation. 



It seems probable that the Inawashiro Lake fills up a depres- 

 sion formed by evisceration of the ground, resulting from the 

 copious outpourings of volcanic products in its vicinity, notably those 

 of Bandai. The origin of the lake, according to current tradition, 

 is ascribed to a great terrestrial disturbance which took place in the 



