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

86 GEOLOGICAL RESEARCHES IN
ing perfect crystals of hornblende and altered felspar, with scattered grains of quartz.
The rock often presented in the fresh fracture all the appearance of an earthy lava,
its detrital origin being most apparent on the weathered surface. The stratification
dips northward toward the sea.
Totohoke lies at the foot of the volcano Esan.
June 6th. We ascended on horseback to the crater of Esan volcano, which forms
the eastern point of the peninsula.
This, also, is a solfatara, its latest eruptions, of which there is no record, having
been confined to flows of sulphurous mud. No pumice was seen, and the fragments
of rock that formed the ejecta were of the same character as the walls of the crater,
excepting some blocks that seemed to be pieces of the white quartz porphyry found
at Kakumi, which had been torn from the interior of the mountain.
The crater, which seemed to be larger than that of the Sawaradake, is divided
unequally by a high ridge of detritus. The walls, where observed in our passing
examination, were found to be so altered by the constant action of acid vapors, as
to render the character of the original rock very obscure, but I thought myself able
to trace a similarity, through a series of specimens, between this and the more common ejected blocks. These latter consist of a dark gray cellular lava of porphyroidal texture. The crystals of felspar, which are numerous, are changed to a
white earth, isolated specimens still retaining numerous crystals of hornblende; but
the most characteristic feature is the abundance of quartz. This last mineral is
present in well-defined, double pyramid crystals and in grains one-eighth to onethird of an inch in diameter. The grains are both limpid and milky white, and
opalescent. They are highly fractured, and often present the appearance of having
contracted and cracked in passing from a gelatinous to a hardened condition. There
is often a strong resemblance between these rocks and the fragments inclosed in
the tufa-conglomerate of Totohoke.
The walls of the crater are rapidly disintegrating and falling, to be converted
into clay impregnated with sulphur, alum, and other salts. Everywhere the scene
is one of ruin. Here is visible on a grand scale the decomposing action of sulphurous acid and steam, the effects of which we see in the altered trachytic rocks of
Hungary, and still progressing on a small scale in the Neapolitan solfatara. Nowhere have I seen so well exhibited the levelling power of nature when she brings
into action her more active agents.
Steam surrounds us, issuing in jets from fissures on the sides of the crater, and
rising slowly, as smoke from a smouldering fire, out of the taluses of debris. But
the main vents are small, mud craters or geysers. Those which we visited were in
the centre of one of the divisions of the crater. They were springs or pits, each
covered by a great vault of hardened mud, like an immense bubble or an inverted
bowl, from ten to twenty-five feet high, the sides and roof from six inches to two
feet thick.
These quake with the constant reverberation of the struggling steam and mud,
which last, judging from the sound, must rise to near the surface. The inner surfaces of these vaults are lined with sulphur in massive layers, in crystals, and often
in long stalactites, and the vapor is highly charged with sulphuretted hydrogen.