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

102 GEOLOGICAL RESEARCHES IN
ments of a green serpentinoidal rock, which seemed to be a variety of the
amygdaloid, occur in the creek.
September 4th. Descending to the sea we rode southward along the shore,
under cliffs of the volcanic conglomerate, as far as the large village of Kumaishi.
September 5th. Leaving Kumaishi we followed the beach southward. From
the village south the shore bluff is formed by a vertical cliff of white pumice-tufa,
sufficiently hard to permit the making of steps in it. It is in thick beds having
a southerly dip. South of Hiratanai this pumice-tufa is covered by the usual
tufa-conglomerate.
A short distance east of Hiratanai a flow of amorphous lava, resembling that
which occurs in fragments in the conglomerate of Isoya and Futoro, flows over the
face of the bluff-the erosion of the
Fi. — - - conglomerate having progressed to
-Fig. 18 1 L I, L L LL L L t-be-o Lr
Fig. 18L L(L L L L aiL L nearly its present condition before
LLL L LL, li- the flow, A conical hill with a
/iLL c O crateriform depression, lying several
c7 a c> o 4 miles inland, was observed from the
/c~ 3, n p o CD beach, and was possibly the source
—, y e o ~ o of the stream.
1138^ a ~cl~~~ ^Beyond this point, as far as Toa. Lava flow. b. Tufa-conglomerate. marigawa, another bed of pumicetufa, overlying the conglomerate,
forms the bluff-rock and the skeleton of the terraces that extend several miles
inland.
At Tomarigawa we left the sea-shore and entered the mountains, and ascending
to the watershed between the Japan sea and Volcano bay, we descended the eastern
slope to the mines of Yurup.
Our road, during this distance, lay, all the way, over the volcanic tufa-conglomerate formation, which extends entirely across this part of the island, and forms the
ridge at a height of perhaps 2,000 feet.
This deposit is cut up by deep valleys with steep sides. In these I noticed outcrops, beneath the conglomerate, of granite, two or three miles from the sea, and,
further eastward, of the argillaceous rock with vermiform fossils already mentioned
several times.
TlIe lead mines of Yurup are in the valley system of the river of the same name.
Here a widely extended erosion has removed the volcanic conglomerate, for a
considerable distance, exposing a very extensive development of a black metamorphosed argillite, which was found to contain the vermiform fossils so often
mentioned in the previous pages. The strata are tilted up, often almost vertical,
and are frequently connected with broad bands, apparently dykes, of greenstone.
The lead-bearing veins occur in both these rocks. The vein-mass consists of quartz,
carbonate of manganese, calcite, and, in one vein, crystals of barytes. Besides
these minerals the galena is associated with zincblende, and pyrites of iron and
copper.
The veins vary from two to eighteen inches in thickness, being more regular in