STRATIGRAPHY OF THE MIDDLE YANG-TZI PROVINCE. or5 
Broadly speaking, the entire formation is composed of dark gray or 
blackish limestone, with a few seams of shale and even anthracite coal 
in occasional local layers. In detail the various horizons show some indi- 
viduality worthy of note. 
The lower part of the formation, from the headwaters of the Ta-ning- 
ho to Wu-shan, contains abundant nodules of black flint. So persistent 
and peculiar is this feature that it may be relied on as a means of identi- 
fying the horizon. A local variation is observed in the gorge just above 
Ta-ning-hién, where soft green shales and thin limestones are substituted 
for 200 feet, 60 meters, of the massive limestone at a horizon about 800 
feet, 250 meters, above the base of the formation. Along the Yang-tzi, 
below K’ui-chéu, the succession is similar, and a thin layer of quartzite 
is interbedded with the limestone near the base of the formation. 
Anthracite coal occurs on the Ta-ning-ho, in the limestone at Tung- 
kuan-k’6u about 1,200 feet, 350 meters, and at T’an-mu-shu-p’ing about 
2,000 feet, 600 meters, above the base. At Tung-kuan-k’6u the occurrence 
is very local; at T’an-mu-shu-p’ing there is a bed apparently about a 
meter thick and mined throughout the syncline on both sides of the river. 
It does not occur at the appropriate horizon elsewhere. The limestones 
are partly shaly at the coal-bearing horizon; yet the massive limestones 
predominate and the coal is sometimes embedded in them directly. 
We have stated on a preceding page that the Wu-shan limestone lies 
upon the Sin-t’an shale in apparent conformity. Throughout the greater 
part of this limestone organic remains are either absent or vestigial, but 
occasionally they appear in considerable numbers. We have collections 
from three different horizons, all of them secured in the upper canyons 
of the Ta-ning-ho. According to Girty they are related to the Upper Car- 
boniferous (Pennsylvanian) faunas of the United States, but the facies is 
distinctly different from that of the typical Pennsylvanian. The resem- 
blance is rather with the Pennsylvanian faunas of western North America, 
and still more with the faunas of the Salt Range of India and the Gschel- 
stufe of Russia. Some of the other collections from this formation, as 
well as some of those obtained at other points, suggest the typical Pennsyl- 
vanian much more distinctly than the three which follow. They mostly 
comprise but a few species in a poor state of preservation, and the resem- 
blance may fairly be said to be, in part at least, due not so much to the 
presence of types peculiarly Pennsylvanian as to the absence of such as 
are characteristic of other faunas and the presence of widely distributed 
ones which are common to many faunas, the Pennsylvanian among them. 
It might reasonably be expected in some cases that more complete collec- 
tions would considerably reduce the relationship at present appearing. 
