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GEOLOGICAL RESEARCHES IN 



rig. 17 



higher level in the mountain, making it a mud volcano, like Esan, and exuding the 

 products of decomposition as fast as formed. On the withdrawal of the water to 

 a lower level the abandoned network of fissures was fiUed by the decomposition of 

 sulphuretted hydrogen. 



At another place, in the walls of one of the small craters near the summit, there is 

 an instance that would seem to illustrate the action of the gases and steam without 

 the presence of water as such. The black rock, already mentioned as occurring in 

 the wall of one of the craters, is visible in different stages of alteration. In places 

 it was observed to have the concentric structure assumed by many rocks during the 



first period of disintegration, and by which the 

 polygonal form of the blocks, into which all bodies 

 of rock are subdivided, is lost as each succeeding 

 shell is removed. In this case the outer shell is 

 white and earthy. Again the same rock was found 

 altered to the centre of each block, the shape re- 

 maining, to a soft, x^asty, white clay, quite tasteless. 

 Often in the centre of a snowy white mass of this 

 clay would lie a core, equally soft, but black, the 

 line of separation between the colors being well 

 marked. In places, where the alteration was in the 

 first stage, an alum salt Avas found forming an efflo- 

 rescence on the surface of this black rock, possibly as one of the first products from 

 the decomposing felspar. 



An emerald-green soft mineral occurs mcrusting, to the depth of a line or more, 

 the walls of the gully where these phenomena were observed. 



On the west side of the peak, in the valley which drains the craters, there was 

 formerly a spring of chalybeate water, which has left quite a deposit of oxide of 

 iron filled with the leaves of a cane, apparently of the same species that covers the 

 surrounding country. At present there is no cane on this part of the mountain, 

 although it grows within a few hundred yards of the spot. This space, which is 

 bare of cane, abounds in Winter-green (Gaultheria) with white berries. 



In close proximity to this deposit a white altered rock, filled with threads of 

 sulphur, attests the former action of the gases in this spot which is now removed 

 from the nearest field of activity. 



From the summit of the Iwaounobori I counted fifteen mountains, aU of which 

 seemed to be of volcanic origin. Among these I include Esan, Sawaradake, and 

 Oussu, all solfataras, which, from their ruined condition, I would not have recog- 

 nized as volcanoes at this distance had I not known them to be such. 



A few miles away to the S. S. E., beyond the broad valley of the river Shiribetz, 

 rose a magnificent cone also called the Shiribetz. This cone is the most symmetri- 

 cal of any that I have seen, not excepting the beautiful Fuziyama, the pride of the 

 Empire. Of its height I had no means of judging, but I thought it could not be 

 less than 6000 feet. It rises from a broad plain, at least the slopes visible to us 

 merged gently into the sweeping cross curves of the valley of the Shiribetz river. 

 The unbroken surface of its sides was covered from base to summit with vegetation. 



