94 GEOLOGICAL RESEARCHES IN 



Crossing the valley of the Shiribetz we came to the foot of the Raiclen promon- 

 tory, a bold headland presenting vertical cliffs toward the sea, and apparently made 

 up of lava flows and tufa-conglomerate. In crossing this mountain we frequently 

 found fragments of a black scoria with long-drawn cells. 



After a laborious journey of several hours we descended into a deep and gloomy 

 gorge containing a warm spring. Here again we found the same variety of white 

 quartziferous porphyry that we had seen at Kakumi and elsewhere. It is im- 

 pregnated with iron pyrites which in places is represented only by cubical cavities 

 containing sulphur. The rock traversed by this porphyry is of a brecciated argil- 

 laceous character, resembling that at Kakumi. It is from this rock that the springs 

 flow, with a temperature varying, in different ones, from 46° to 50° C. These rocks 

 are exposed only in the bottom of the ravine, on either side of which they are 

 covered by the volcanic formation. 



August ITth. Hising from the ravine we continued our journey over the northern 

 part of the Eaiden, the outcrops here, as yesterday, being of a gray trachytic lava 

 with a tendency to tabular structure. This continued till we descended at the creek 

 Nibitzunai to a terrace that reaches many miles northward and eastward, low near 

 the sea, but rising rapidly toward the mountains. Skirting this for a few miles 

 we reached Iwanai. 



August 18th. At Iwanai we left the sea and made an excursion to the volcano 

 Iwaounobori^ about thirteen miles inland. 



The first five miles of the road lay over the terrace which, as we approached the 

 mountains, rose very rapidly. During the first mile or two, after leaving the sea, 

 the surface was covered with a dense growth of long-jointed grass, six or seven feet 

 high, to which succeeded the usual forest of large maples, oaks, mountain and white- 

 ash, beech, birch, fir, and scattered magnolias, filled in with an impenetrable under- 

 growth of cane eight to twelve, and even fifteen feet high. The road through this 

 region, being deep with mud which was full of sharp pointed stumps of the cane, 

 was one of the worst I have ever seen. 



Entering the mountains we passed through a crateriform valley, once the bed of 

 a lake, and, ascending to a pass in the hiUs beyond, we saw, beneath us, a beautiful 

 little lake. On the other side of this rose the volcano, or rather solfatara, with its 

 yellow, sulphur-coated clifi"s. Here again the regular slopes and symmetrical out- 

 lines of an undisturbed cone are entirely wanting; the outer as well as the inner 

 walls were rocky precipices, and the ruin seemed greater than at Esan. We reached 

 the summit without much difficulty. 



The present mountain is evidently only part of the skeleton of a former cone of 

 large size. The predominating formation, from the spurs at the base to the summit, 

 is a dark gray volcanic rock, showing in places a tendency to stratiform structure, 

 and apparently of the trachytic family, the chief ingredient being crystals of a 

 white felspar.^ The former mantle seems to be still represented by fragmentary 



' Japanese. Iwaou, sulphur; and nobori, a term for mountain, from nohoru, to climb. 

 ° With the exception of one specimen of rock, and a few minerals, the entire collection of rocks, 

 shells, etc. from north of Odaszu, was lost by the wreck of a junk on the way to Hakodade. 



