52 COGGIN BROWN : MINES & MINERAL RESOURCES OF YUNNAN. 



western portion may really be Cambrian. According to Deprat 

 they attain a thickness of not less than 2,000 metres between the 

 parallels of Yunnan Fu and the Yang-tze. The series is essentially an 

 arenaceous one and sandstones, slates and schistose shales are of 

 far more frequent occurrence than the rare bands of brecciated and 

 crystalline limestone. In spite of the great amount of disturbance 

 they have undergone and their original variations inseparable from 

 the formation of a detrital deposit in a shallow Sea, two divisions 

 have been recognised, viz., the Georgian and Lowest Acadian. 



(4) The Ordovician System. 



Fossiliferous rocks of this age have been found in three locali- 

 ties in Western Yunnan. They are of little importance as far as 

 the general structure of the country goes or as regards the size of 

 the area they occupy, but they are of great interest from a palseonto- 

 logical point of view. Having read in Loczy's work of the exis- 

 tence of cystidean plates in certain beds near Pu-piao, a village 

 one stage west of Yung-ch'ang Fu, I made a careful examination 

 of the locality and was rewarded by the discovery of a rich fauna ; 

 it has been described by Mr. Cowper Reed. At a later period I 

 discovered the fossiliferous localities of Shih-tien and Lameng 

 further to the south, as the map shows. 



(a) The Pu-piao Beds. — Reddish-yellow, and greyish-green sandy 



shales with bands of hard, nodular, impure limestone 

 overlain on both east and west by younger Palaeozoic 

 limestones and associated rocks. Graptolites and 

 trilobites are the characteristic fossils. Mr. Cowper 

 Reed believes that the fauna, of which 34 distinct 

 species have been recognised, undoubtedly points to a 

 Lower Ordovician age. The graptolites are a typical 

 assemblage from the zone of Didi/mograptus Murchi- 

 soni. — The other organisms are allied to or comparable 

 with members of the North European fauna of Ordo- 

 vician times and scarcely any traces of an American 

 element are apparent. The Pu-piao beds have been 

 correlated therefore with the Llandeilo beds of the Bri- 

 tish Isles. 



(b) The Shih-tien Beds.- Rod, earthy limestones ; massive, 



light grey limestones ; greenish-grey limestones ; harden- 

 ed marls ; calcareous mudstones and dark slates. The 



