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

10 GEOLOGICAL RESEARCHES IN
CHAPTER- III.
OBSERVATIONS IN THE PROVINCE OF CHIHLI.
ALONG the western boundary of the province of Chihli, the great delta-plain is
bounded by the outliers of the northwestern belt of N. E. S. W. ridges. The
foundation on which rest the limestone and volcanic rocks of Northern Chihli,
Shansi, and Shensi, consists of granite and the metamorphic schists; and where
this foundation forms the northwestern limit of the delta-plain, it forms also the
southeastern edge of the skeleton of the great table-land of Central Asia.
We have seen that, in Central China, the granitic and metamorphic rocks that
support the limestone and Coal measures, rise to-the level of the river, in, to say
the least, only rare instances, and then as the axial cores of ridges; the great
thickness of the overlying rocks making it highly probable that, from western
Sz'chuen to the Pacific, this foundation lies far below the level of the sea. But if
we cross the mountains from the delta-plain to the highlands of Mongolia, we find
that the surface of the granitic substructure lies everywhere above the sea, and
probably nowhere at a less height than 1000 feet. Were the limestone and
younger rocks removed, the country would present the appearance of a table-land
ribbed with high N. E. S. W. ridges, and very similar to southern Mongolia if we
suppose that divested of its lava beds.
Along the edge of the plain, the limestone floor of the Coal measures rises
abruptly from under the delta-deposit, and forms, so to speak, the eastern facing of
these mountains. At the entrance to the Nankau pass, the strata trend N. 60~ E.
and dip about 40~ to S. E. Five or six miles farther west, it is followed by granite,
and between these points, strike and dip are very irregular. From the pass, the
limestone stretches away to N. E. toward Jehol, and to S. W., facing the plain,
toward Shansi.
While the Coal measures probably remain intact under the delta-plain, from the
mountains of Shantung to those of Chihli, they exist in these latter only in scattered
basins, where they have been partially preserved, by folds of the limestone, from
denudation. The most important instances of this kind facing the plain, are the
basins of Wangping (hien) and Fangshan (hien) west of Peking, and of Pingting
(chau) in Shansi.
The basins of Wangping (hien) and Fangshan (hien) lie in the mountains west
of Peking where, rising from under the plain, they occupy synclinal folds of the
limestone, and are probably only two arms of a larger basin concealed under the
younger deposits to the eastward. The Wangping basin extends due west more
than thirty miles, with a breadth of about twelve miles. Along a great part of its