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

CHINA, MONGOLIA, AND JAPAN. 35
ends and corners of small crystals of the constituent feldspar and quartz are sharply
developed.
The hills immediately surrounding Siwan, in the Great Wall range, east of Kalgan, consist of a reddish-gray syenite composed mainly of orthoclase, some gray
triclinic feldspar, crystals of hornblende, and a little quartz. Large crystals of
orthoclase render it porphyroid. Near the contact of this rock with the crystalline
schists west of Siwan, dykes of it are seen in the latter, while fragments of the schists
inclosed in the main body of the syenite are additional proof that it is eruptive, and
younger than the metamorphic schist formation. Fragments of this syenite are
inclosed in the pluto-neptunian rocks of the Kalgan porphyry.
A syenite of medium grain, composed of slightly pink orthoclase and hornblende,
occurs over a large part of the rolling land east of Murkwoching.
Fragments of a fine red granitite occur in the bed of the Yang Ho near Kiming,
and blocks of a red rock composed of fresh, bright-red orthoclase and grains of a
soft, talcose or steatitic mineral, thus approaching a protogine, are common in the
Hwaingan creek. At this latter locality there are many fragments of a rock, consisting entirely of a coarsely crystalline, triclinic, feldspar, apparently labradorite, of
a grayish tinge tending to blue and weathering white. It contains scattered crystals of a mineral resembling sahlite.
Crystalline Metamorjphic Rocks.-The tilted and folded strata of these rocks form
for the most part all the ridges we have passed over after leaving Chatau. In the
hills northeast of Shachung are beds belonging to the chloritic series-white triclinic
feldspar, quartz, chlorite, and magnetic iron-a variety of chloritic gneiss.
In the hills traversed by the road from Kalgan to Siwan, and south to Chauchuen,
the predominating rocks are still those of the chloritic series. In the hills south of
Siwan I observed chloritic gneiss-orthoclase, chlorite, and quartz-and schist of
nearly pure chlorite. In the mountains between Kalgan and Siwan, another welldefined variety of chloritic gneiss occurs, in which the feldspar is, in great part,
triclinic. Schists of the hornblendic series also play an important part in this region.
They are composed of a greenish-white triclinic feldspar and hornblende, sometimes
one of these minerals predominating, sometimes the other. The trend of the uplifts
in this region, though irregular, seems to lie between N. and W.
Under the Hwaingan beds near Kiu Hwaingan, the metamorphic schists here
represented by gneiss, lie with a remarkable approximation to conformability with
these younger strata. This gneiss consists of orthoclase and quartz, and is very
poor in mica, excepting on the surface of the slabs into which it breaks.
The Barrier range, where we cross it west of Yangkau, is formed mainly of
schists of the hornblendic series. Among these are extensive strata of a rock composed of black hornblende, with strongly defined prismatic cleavage, abundant garnets, and a little white feldspar. Another rock occurs among these strata composed
of a greenish-white triclinic feldspar associated with a little black mica, quartz, and
hornblende.
The substructure of the plateau, southeast of the Te Hai, is of granulite and
gneiss. The former rock is in places fine grained and schistose with minute garnets, but occurs more generally with a coarser structure, in which it is seen to con