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

CIlINA, MONGOLIA, AND JAPAN. 13
chambers extending nearly in a straight line. The first two of these only were
visible, the entrance to the third having been closed by an imperial order, owing
to a party of visitors having lost their way and perished.
These chambers are connected by passages, so small that they can be entered
only by creeping on hands and knees. Their longest axis is at right angles to
the strike of the strata, and forms a considerable angle with the dip. The floor is
covered with stalagmite, which, in the centre of one chamber, seems to be at least
forty feet thick, and is connected with the roof by immense columns of stalactite.
Like many large caverns in China, this one is sacred to Buddha, of which deity
there is a well executed high-relief sculptured in the wall of the entrance; and the
small passages have been worn and polished by the knees of pilgrims during
centuries.
I looked in vain at the face of the rock at the entrance, for some signs of a crack
corresponding to the plane of these chambers.
Some of the deep and narrow ravines of the surrounding hills, seem to have been
formed by the caving in of similar caverns.
In parts of the empire, these caves abound in fossil bones, which are excavated
and used in medicine, under the name of " dragon's bones," " dragon's claws," etc.
This limestone, forming, as it does, the floor of the Coal measures, appears,
surrounding the different basins of these, in highly inclined beds, forming as it
were a narrow frame, or, having a gentler dip, it occupies a broader space.
Porphyry Conglomerate.-In the mountains that border the Wangping basin on
the north and west, there are extensive masses and dykes of porphyry, which have
raised and cut through the limestone in all directions. From the detritus of this
intrusive rock, the beds of the lower Coal measures at Chaitang, which are equivalent
to those marked No. 3 in the table, seem to have been formed. The reason for
supposing this, is, that as we approach the northern edge of the Chaitang basin,
we find the porphyry conglomerate underlying, in the form of a flat boss, the beds
forming the lower half of No. 5 which are eminently characterized by two peculiar
rocks, that marked as "compact green argillite" and the still lower ones, "green
quartzose conglomerate." Further on we find, that the porphyry conglomerate
contains interstratified beds of sandstone. The fragments that form this extensive
member of the Chaitang series, are, for the most part, derived from the masses of
porphyry nearest at hand. Thus near Chingtai they are chiefly green felsitic
porphyry, similar to that forming dykes in the limestone at Hiamaling, a few miles
distant, while, along the Hun river, red and green varieties predominate, intrusive
masses of both kinds occurring in the neighborhood.
Fragments of limestone and quartz are frequent in the porphyry conglomerate,
and would seem to characterize its upper portion. Thus I have indicated in the
table two distinct varieties, though perhaps on insufficient grounds.
This conglomerate furnishes an important page in the history of the Coal measures
in this region. It shows us that there had been an elevation of the limestone,
perhaps caused or accompanied by the intrusion of the porphyries, before the
overlying rocks were deposited. The presence of fragments of limestone, quartz,