79 



CHAPTER IV. 

 Gotlandian, 



We have already seen above that marine sedimentation took place un 

 interruptedly from the Ordovician to the Gotlandian at the south of Tsin-ling- 

 shan, and thus the Gotlandian fossiliferous rocks are found in association with 

 those of the Ordovician in most cases. 



Frech^' who studied the Usui Collection of fossils from Tung-hu-hsien, 

 found in it a Pcntamerus borcalis Eichw. This species points to the Lower 

 Gotlandian, and thus the development of the Lower Gotlandian, in intimate 

 stratigraphical relation with the Upper Ordovician — with the characteristic 

 fossils mentioned in the preceding chapter — becomes palaeontologically con- 

 firmed in this district. 



From the district of Kiau-tschang-pa, prov, Sze-chuan, Richthofen^' 

 reported fossiliferous Ordovician-Carboniferous rocks in the following strati- 

 graphical succession : 



f. Black and brown, very bituminous limestone — Carboniferous. 



g. Grey limestone and fragile grey marl, with Atrypa reticularis — 

 Devon. 



h. Green shale, with intercalation of coralliferous limestone nodules with 

 many brachiopods and corals. 



i. Limestone bands ; very impure, being argillaceous. Many corals. 



k. A thick complex of green shale, with a few interbedded thin lime- 

 stone layers ; the limestone contains brachiopods. 



1. Limestone, intercalated with sandstone, shale, and siliceous lime- 

 stone ; red limestone is characteristic. Many triobites and brachio- 

 pods.^^ 



1) Frech: in Richthofen's China, vol. V., pp. 14-15. 



2) RiCHTHOFEN: China, vol. II., Chapt. XII., pp. 596-598. 



3) RiCHTHOFEN found these fossiliferous deposits ranging b-'tween Ordovician and Carboni- 

 ferous in age to be in a very regular succession in the Chao-tien mountains; I am, how- 

 ever, not quite sure whether this is really the case. It is hardly credible that there is no 

 strati graphical break in this section. 



