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

CHINA, MONGOLIA, AND JAPAN. 105
hornblende-felspar rock. Here also the mean trend of the highly contorted beds
is between W. and N.
The remaining older rocks of this part of the island belong to the Ichinowatari
series, and the argillite beds containing the obscure vermiform fossil, so often mentioned. The Ichinowatari series are black and gray metamorphosed argillacecus
rocks, associated with older or younger shale containing calamites of unknown age,
and with greenstone; and they are characterized by metalliferous veins occurring
at least in both the argillaceous rocks and in the greenstone.
The argillite beds we find at many points, throughout the region included in the
above itineraries, occurring in places either as a compact gray rock or as a shale,
while at Yurup it is metamorphosed to a compact black rock, tilted almost to perpendicularity. Between Tomarigawa, on the west coast, and Yurup, on Volcano
bay, it is found, excepting in one locality, to be the predominating rock wherever
the ravines have cut through to the bottom of the volcanic tufa-conglomerate strata.
The rocks in question have, in common with the Ichinowatari series, their argillaceous character, their association with dykes and great masses of greenstone and
an identity of character in the metalliferous veins of the two localities, both as
regards the association of minerals in these and also as regards some peculiarities
in the condition of the greenstone near these veins.
Finally we have seen, beyond Iwanai, near Ousubetz (north), a coal-bearing series
of more or less metamorphosed rocks, containing fossil Equiseta.
We find, in the auriferous gravel of Kunnui, representatives of another class of
metamorphic rocks in the chloritic and micaceous schists, etc., which are probably
the source of the gold, and evidently exist in situ in the ridge between that place
and the Japan sea.
The enumerated strata form, so far as my observation extended, the skeleton of
Southern Yesso. The local strike of the coal-bearing rocks of the Ousubetz (north)
is N. 300 E., being nearly at right angles to the N. W. trend of the peninsula on
which they occur. All the other beds of the older rocks seem to have been affected
chiefly by an uplift trending between N. and W., and to which that portion of the
island lying between Esan volcano and the mouth of the Toshibetz, on the west
coast, appears to owe its direction.
We come now to the pluto-neptunian beds, consisting of great masses, more or
less stratified, of volcanic products in the form of tufas, sandstones, and coarser
conglomerates and breccias.
This, by far the predominating formation, forms almost everywhere sloping plains
or terraces between the mountains and the sea-shore, and extends, at least in
places, entirely over the watersheds between Volcano bay and the Japan sea, forming peaks, as the Obokodake, several thousand feet high.
The petrographical character of these beds is very different, not only in their
vertical, but also in their horizontal development. Along the west coast we find
thick beds of a white pumice-tufa associated with conglomerates made up of fragments of a black compact rock, almost a pitchstone. Along the road from Tomarigawa to Volcano bay the lowest beds observed were of a more clayey pumiceous
tufa, and above these an immense development of a scoriaceous conglomerate14 July, 1866.