Geological researches in China, Mongolia, and Japan, during the years 1862-1865.

96 GEOLOGICAL RESEARCHES IN
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 filled 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-,xQ\a maining, to a soft, pasty, 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
//A^ \\/////~ marked. In places, where the alteration was in the
first stage, an alum salt was found forming an efflorescence on the surface of this black rock, possibly as one of the first products from
the decomposing felspar.
An emerald-green soft mineral occurs incrusting, 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, all 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 recognized 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 symmetrical 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,