STKATlGRAPItY 



263 



Provisional straiigraphic Table — Continued 



System. 



Series. 



Lithologic character. 



Locality. 



Devonian 



Middle 



Devonian. 



Siliceous white crj-stalline 

 limestone ( invertebrate 

 fossils), associated with 

 a lai'ge amount of igneous 

 material. 



Blue limestone (Salmon- 

 trout limestone), over- 

 laid by shales. (Inver- 

 tebrate fossils. ) 



(Unconformity?) 



Occurs along Yukon 

 river and at old 

 Rampart village on 

 Porcupine river and 

 probably in other 

 parts of the basin of 

 Porcupine river. 



Devonian ''.... 





Heavj' blue and white 

 siliceous limestone (frag- 

 m e n t a r y invertebrate 

 fossils), with slates, 

 q u a r t z i t e s, and thin- 

 bedded limestones. 



(Stratigraphic position 

 doubtful. ) 



Yukon river, 8 miles 







below "Woodchopper 

 creek. 



Silurian ? 





Fine conglomerates, 

 cherts, graywackes, and 

 slates, with some lime- 

 stones. 



(No fossils; age determi- 

 nation doubtful.) 



In region 1 v i n g be- 







tweeen Faubanks 

 and Rampart. 



Silurian 



Middle 



Magnesian limestone. (In- 

 vertebrate fossils. ) 

 (Conformity?) 



Porcupine river. The 

 same formation prob- 

 ably occurs in the Yu- 

 kon-Tanana region. 



Ordovician 





Non-magnesian limestones. 



(Invertebrate fossils.) 

 (Unconformity?) 



Porcupine river. Prob- 

 ably present in other 

 parts of the Yukon 

 basin, but not posi- 

 tively identified. 







Pre-Ordovician. 





Slates and quartzites, with 

 some limestones. (No 

 fossils. ) 



Porcupine river. 







Pre-Ordovician? 





Quartzites, quartz, schists, 

 mica-schists, and lime- 

 stones. Includes some 

 gneisses, granite, and 

 greenstone intrusives. 



Extremely developed 

 in the Upper Yukon 

 basin. 











Probably equivalent to the slates and quartzites 

 ( pre-Ordovician ) of the Porcupine river. Includes 

 the Birch Creek schists and Nabesna series. 



