292 RESEARCH IN CHINA. 
occurrence of the Middle Ordovician fossiliferous horizon near the con- 
tact. Four kilometers further upstream this same fossiliferous horizon 
was found at the top of a short section of the limestone, which in turn 
occurred on top of the Sin-t’an shale. We at first took the limestone for 
the Wu-shan, since that formation would naturally occur above the Sin- 
t’an, but afterwards determined by the fossils that it was the Ki-sin-ling. 
It is probable that this contact is along an overthrust fault, which dips 
steeply to the south and brings the Ki-sin-ling up over the Sin-t’an shale. 
The sections are drawn on this interpretation. 
The section from Tung-kuan-k’ou to Chén-p’ing-hién is an anticlino- 
rium, in which the Ki-sin-ling limestone is the oldest formation represented 
and forms the major part of the exposure. We leave the canyon of the 
Ta-ning-ho at Tung-kuan-k’ou, and the line of section extends north across 
the mountains at an altitude of 5,500 feet, 1,600 meters, in the pass and 
8,500 feet, 2,600 meters, in the adjacent summits. The exposures were 
much less complete than in the magnificent canyon walls of the Ta-ning-ho, 
and the structure appeared to be more complex. We therefore present 
the facts in Section DD, atlas sheet d 6, with somewhat less confidence 
in the accuracy of our observations than for the sections further south, 
yet in their major features the structures rest upon the recognition of well- 
defined horizons checked in part by occasional discoveries of fossils, and 
there is a probability that the drawing correctly represents at least the 
major facts. At Tung-kuan-k’ou the Wu-shan limestone is represented 
in a mass which dips steeply to the south and which is characterized by 
a bed of anthracite coal and by the occurrence of Upper Carboniferous 
fossils. From sketches made of the distribution of strata in the adjacent 
mountain on the south, it is believed that this body of limestone is a closed 
syncline immediately north of a plicated mass of Sin-t’an shale, which 
is cut by the river as far as the underthrust contact with the Ki-sin-ling 
limestone. The little brook which flows from the Ki-sin-ling pass to 
Tung-kuan-k’ou cuts a very remarkable gorge through this outcrop of 
the Wu-shan, a gorge 1,200 feet, 360 meters, deep and scarcely 100 feet, 
30 meters, wide.* Above this little canyon the valley widens out on the 
shales, which represent the Sin-t’an and which present a nearly uniform 
steep southern dip. As the exposed thickness of the shales is very much 
greater than that which they have in normal sequence, it is probable that 
they are duplicated by isoclinal folding. Near Ta-miau-ssi there is a sec- 
tion of much plicated thin limestones, which we assigned to an anticline 
of the Ki-sin-ling, and above this occurs a belt of heavy gray flagstones, 
which we took for the Sin-t’an. A mass of the Ki-sin-ling limestone, 

* Plate XLIX, 
