84 RESEARCH IN CHINA. 



also the Lower Jurassic. The Sang-hu is thus probably nearly equivalent 

 to the Kui-chou series. 



On the Yang-tzi still, but several hundred miles further west, occur the 

 exposures of Permo-Mesozoic strata which form the foothills along the moun- 

 tains of western Hu-pei. Pumpelly described them as he saw them near 

 I-chang, and his account is given in volume I, p. 278, of this report. Vogel- 

 sang* repeatedly refers to them as being observed in a trip from I-chang 

 northward as far as the 32d parallel, from which he returned via Chu- 

 shan and the Ta-ning-ho; the latter part of his route coincides with that 

 subsequently followed by our expedition. 



We observed strata above the Upper Carboniferous (Wu-shan) lime- 

 stone in numerous sections on the Ta-ning-ho and Yang-tzi'-kiang, but 

 did not examine them closely. There was great uniformity of stratification 

 and, despite the marked difference between the massive limestone and the 

 red shales which followed it, seemingly perfect conformity of dip between 

 the two. Both in the field and since, I have regarded the relations as those 

 which result from marine scour by shallowing waters. The limestone, 

 having accumulated and hardened beneath waters which were deep enough 

 to permit sediments to gather, was swept clean by a current which flowed 

 across it, possibly with accelerated velocity, while the waters shallowed; 

 and ultimately, in consequence of continued shallowing, the current was 

 checked or diverted and red terrigenous deposits were laid down on the 

 scoured surface. This sequence implies the nearness of land areas and 

 possibly of subaerial erosion of the Wu-shan limestone in adjacent areas 

 to a degree consistent with the occurrence of such conglomerate of flints 

 we observed in the float of the Ta-ning-ho. f 



In the limestone, 400 feet, 120 meters, above the base of the red series, 

 'cur fossils which Girty refers to the late Paleozoic, but with doubt. J He 

 says: 



The evidence upon which the horizon in question is referred to the Paleozoic con- 

 sists of the septiferous Terebratuloid, the round crinoid stems, and the general Paleozoic 

 complexion of the meager fauna. It is inconclusive and may not stand against any facts 

 which strongly point to a Mesozoic age. For this reason my assignment to the Carbonif- 

 erous is provisional merely, and should the necessity arise of changing to a younger period, 

 the readjustment would entail no serious conflict of evidence. 



Girty 's conclusion from the fossils is in accord with the stratigraphic 

 evidence that deposition was more nearly continuous here than in areas 

 adjacent on the north and west. The episode of marine scour, which is 



*Reisen in nordlichen und mittleren China, Petermanns Mitt., 1901, 47, and 1904, 50. 



fVol. i, pp. 264 and 277. 



t Report on Upper Paleozoic Fossils, vol. m. 



