STRATIGRAPHY OF THE MIDDLE YANG-TZI PROVINCE. PYG(a/ 
PERMO-MESOZOIC. 
PRE-K’UI-CHOU UNCONFORMITY. 
The relation between the Wu-shan limestone and the K’ui-chéu series 
was not determined by close observation of the contact in the field. The 
upper surface of the limestone may be eroded on a plane very nearly parallel 
to the stratification, but we saw no evidence of such an effect. The im- 
mediately overlying strata, consisting of several hundred feet of red shale 
and a heavy bed of massive bluff-making limestone, were the same in 
the different sections seen on the Ta-ning-ho and near K’ui-chéu on the 
Yang-tzi. The presence of a hiatus is suggested, however, by the marked 
difference in character between the two formations and by the presence 
of coarse conglomerates which, at I-chang, lie near the base of the supposed 
K’ui-chéu.* We also found loose pieces of conglomerate in the river gravel 
near the base of the K’ui-chéu below Ta-ning-hién, consisting of pieces 
of the Wu-shan limestone and flints embedded in a hard sandstone. They 
may represent a later formation, but the conglomerate is hard and has 
undergone some mechanical deformation; hence it is probably not younger 
than the period of post-K’ui-chou folding. Von Richthofen describes an 
unconformity with marked discordance of dip at this horizon in Ssi-ch’uan, 
and the unconformity, without marked discordance, may exist in the 
middle Yang-tzi. : 
K’UI-CHOU SERIES. 
In several synclines in the Carboniferous limestone we observed 
incomplete sections of a series which consists mainly of red shales and 
red sandstones with occasional gray limestones. The lower members are 
deep red, but at higher horizons brown, gray, and even black sediments 
occur. Where this series occurs on the Yang-tzi at K’ui-ch6u, Hu-pei, 
it was examined by Pumpellyf and von Richthofen on account of the 
coal which it contains. It is also referred to by Blakiston.t 
In the Ta-ning-ho sections the lowest member consists of deep red 
sandy shales about 400 feet, 120 meters, thick, with which thin seams of 
gray and bright green shales are interbedded at intervals of 1 to 3 feet, 
.3 to 1 meter. Calcareous gray shales become somewhat prominent at 
the top of this member, and are succeeded conformably by a firm semi- 
crystalline limestone of clear gray color, which occurs in beds 1 to 3 feet, 
.3 to 1 meter, thick, is more than Ioo feet, 30 meters, in thickness, and is 
sufficiently resistant to make prominent bluffs along the river. Softer 
strata occur above the bluff-forming limestone, and consist of gray and 
reddish shales with red sandstones and impure limestones in thin strata. 
The details of the sequence are not known. Along the Ta-ning-ho the red 
* Smithsonian Contributions, vol. xv, Geological Researches in China, Mongolia, and Japan, p. 6, 
tIbid. { Five months on the Yang-Tsze. T. W. Blakiston, 1862, page 133. 
