OUTLINES OF GEOLOGY OF YUNNAN. 53 



beds are faulted against Silurian strata on the west and 

 overlaid by alluvium on the east. The characteristic 

 fossils are beautifully preserved cystideans and trilobites. 

 46 species have been recognised, many of which are 

 new. According to Mr. Cowper Reed the fauna suggests 

 the Lower Ordovician, especially the Ordovician and 

 cystidean limestones of the Baltic provinces of Russia. 

 Some American Trenton or Chazy affinities are also 

 indicated and at least one of the species has been 

 previously recorded from the Ordovician of China. 



(c) The La-meng Beds. — Hard reddish or purple calcareous 



slates and mudstones faulted down into rocks of Kao- 

 liang age. The fauna is poor and scanty and only 8 

 organisms have been recognised. These suggest a Lower 

 Ordovician age. 

 There is a marked resemblance between the fossils from 

 Western Yunnan and the Ordovician fauna of the 

 Northern Shan States. Both undoubtedly belong to the 

 Lower Ordovician, and both have an European facies 

 and belong to the same division in South-East Asia. 



(d) Ordovician of Eastern Yunnan. — Deprat has shown that 



certain small exposures of greatly metamorphosed rocks, 

 which come to the surface in Eastern Yunnan, belong 

 to the Ordovician. Cowper Reed has pointed out that 

 the Ordovician faunas of Eastern Yunnan and Tong- 

 king seem to have a completely different faunistic type 

 from those of Western Yunnan, but the data are in- 

 sufficient for a satisfactory comparison. 



(5) The Silurian System. 



(a) Western Yunnan. — The Silurian beds are shown with the 

 Ordovician on the map. They have only been recognised in two 

 localities in Western Yunnan, faulted in one case against the 

 Ordovician on Shih-tien hill and the second further south near Pai-ma. 

 At Shih-tien black fissile slates and greenish-grey or pink flaggy 

 slates yielded a graptolite fauna, belonging, according to Miss 

 Elles, to two horizons. 18 species have been recognised from the 

 zones of Monograpfus Sedgwieki and Orthoceras vesiculosus or Mono- 

 graptus gregarius. 



