86 GEOLOGICAL RESEARCHES IN 



ing perfect crystals of hornblende and altered felspar, with scattered grams of quartz. 

 The rock often presented m 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 foimd 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 com- 

 mon ejected blocks. These latter consist of a dark gray cellular lava of porphy- 

 roidal 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 one- 

 third 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 sulphur- 

 ous acid and steam, the efi'ects of which we see in the altered trachytic rocks of 

 Hungary, and still progressing on a small scale in the Neapolitan solfatara. No- 

 where 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 cyaters 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 sur- 

 faces 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. 



