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

6 GEOLOGICAL RESEARCHES IN
useful and choice marbles. Every degree of thickness occurs in the layers from
laminae only one-quarter inch thick to beds of many feet.
Nodules and thin layers of black chert occur throughout the limestone, but in
the lower half they are remarkably frequent, becoming more common as we approach the oldest beds, in which, indeed, the calcareous rock is often entirely
excluded by massive layers of quartzite. At the eastern entrance to the Lucan
gorge, where the limestone rests on the older rocks, the lowest beds of the former,
containing lenticular masses and thin layers of chert, are soon succeeded by a bed
40 to 50 feet thick, of massive quartzite.
Wherever I have had occasion to examine this limestone in place, it has invariably appeared to be entirely without fossils, but this has been only in the main
ridges, where metamorphic action has probably played a more important part than
in the minor ridges that rise between these lines of greater elevation, and it seems
to me that there can be little doubt that the fossil Brochiopoda that occur in many
provinces belong to this formation.
Just before entering the eastern mouth of the Lucan gorge, a bed of fine-grained,
micaceous, gray sandstone is observable, intervening between the metamorphic
schists and the limestone. The trend of this intervening bed is N. N. W. and the
dip 25~ to 30~ to W. S. W., the metamorphic schists striking to E. N. E. and
dipping to N. N. W., while the trend of the overlying limestone strata, at the nearest
point observed, was about N. by W. and the inclination about 300 to W. by S.
At the western end of the Mitan gorge we enter the coal field of Kwei. Here
the limestone disappears under strata, apparently conformable with it, of a finegrained micaceous sandstone, which, below Kwei, is succeeded by a fine-grained,
gray, calcareous sandstone. The trend of the beds which, near the gorge, was
N. N. E. with a dip of about 40~ to W. N. W., changes here to N. with a dip to
E., and further up, opposite Kwei, it is N. by W. with an inclination of 70~ to E.
by N. Here is the beginning of a series of those angular plications so common to
Coal measures in all countries. Small beds of limestone and red argillite alternate
with the sandstones until, about two miles above Kwei, the first coal seams crop
out, and with the appearance of these, the trend changes to N. WT. by W., more
than 90~ from its normal direction of N. E. S. W.
The seams of coal are of an inferior friable anthracite. Those I visited above
Kwei were highly inclined between sandstone walls, and contained, according to
the Chinamen, only six to eight inches of fuel. Capt. Blackiston, who took specimens of these rocks and noticed, with much accuracy, the general features of this
region, remarks that the rocks of the coal regions of Sz'chuen, wherever he saw
them, presented the same appearance as those of the Kwei field.' It would seem
probable that in Sz'chuen, which seems to be occupied by an immense coal basin,
the Coal measures exist with a much greater thickness than in the Kwei field,
where only the lower members seem to have been preserved. Deposits of iron ore
occur in intimate connection with coal and limestone in Sz'chuen,2 and, as we shall
i Five Months on the Upper Yangtse. 2 Ibid.