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

CHINA, MONGOLIA, AND JAPAN. 89
brown oxide, the upper portion less oxidized and retaining more of the original
character.
How many deposits of iron ores may there not be that owe their formation to a
similar cause, the destruction of ancient eruptive or metamorphic rocks, and the
concentration of their grains of magnetic iron on the surf-washed beaches of former
seas
A few miles further on we came to the outcropping clay slates, which continue,
as the tide-washed rock, as far as Shiwokubi (Cape Blunt). From this point on,
as far as Oyasu, they are also exposed along the beach and form the hills inland,
but are covered between the sea and the hills by the recent terrace deposit, which
we have already seen bordering the Bay of Hakodade.
This slate is black and fissile, and is covered, near Shiwokubi by conformable
strata of compact sandstone with interstratified seams of slate, and at Oyasu by a
sandstone conglomerate containing fragments of the same older rock. These beds
are more or less contorted, all the observed strikes of the uplift lying between W.
and N. 15~ W., averaging nearly N. W.
They are traversed by a great number of dykes of porphyry and greenstone, and
by innumerable veins of quartz with pyrites of iron and, in places, of copper.
The porphyry is of the same white quartziferous variety as that at Kakumi, and
the same description will do for both. The dykes are very sharply defined, from
10 to 50 feet thick, cutting the slates at all angles. The porphyry is in turn traversed by dykes of greenstone.
The quartz veins cut the slates at all angles, and vary in thickness from 2 to
12 feet. They abound in iron pyrites, one vein four feet thick being massive
sulphuret. Some of them were traced between one and two miles inland, the
pyrites changing to oxide away from the sea-shore. An outcropping vein at
Saidoma showed some very fair ore of copper pyrites associated with iron pyrites,
zincblende, and a little scattered galena. The strike of these veins is generally
between N. and E., and one of the smaller ones traverses a dyke of porphyry.
It was in one of these that we made the first blast ever fired in Japan.
Between Shiwokubi and Hakodade, a broad mesa separates the hills from the sea,
rising gently to near the mountain, and then rapidly, and cut into by all the streams
descending from the hills. It is covered with a dense growth of weeds but no trees,
the latter being confined, along this part of the straits of Tsungara, to the northern
slopes of the hills.
At Yunogawa there is an outcrop of black clay slate in which rises a warm
spring with a temperature of 38~ C.
Entering Hakodade we finished the circuit of the peninsula.'
The region thus encircled by our route is a high ridge ~apparently consisting, in
the main, of the metamorphic rocks which have been described as occurring along
the sea-shore, having a general northwesterly trend, accompanied by intrusive
masses of greenstone and quartziferous porphyries. It is fringed on its northern
slope by volcanic tufa-conglomerates that rise, in places, to the lower summits of the
crest, and on the southern edge by recent marine strata. I will add that coal is
said to have been found in the hills near Mt. Esan.
12 June, 1866.