PRE-OEDOVICIAN 267 



and McConnell'*'' had indicated that a zone of similar metamorphic rocks 

 stretched southward into British Columbia. The later investigations of 

 McConnell and his associates have yielded much additional information 

 in regard to these terrains. 



In the Klondike district/^ McConnell recognizes only one grouo of 

 altered sediments — the ISTasina series. This name had previously been 

 applied by Brooks^** to a group of schists and crystalline limestones ex- 

 posed along the lower White river, and he suggested their probable equiv- 

 alency to Spurr's Fortymile and Birch Creek series. McConnell traced 

 these metamorphics westward from this type locality into the Fortymile 

 Eiver basin and proved that they were an extension of the rocks described 

 by Spurr. He too was iinable to differentiate them into two formations. 

 The conclusion that the crystalline limestones and schists can not be 

 differentiated into two formations, at least on the basis of reconnaissance 

 work, finds support by the recent studies of Prindle^^ in the Fortymile 

 region. 



Keele, of the Canadian Survey, has found what appears to be a south- 

 easterly extension of the Klondike metamorphic rocks in Stewart Eiver 

 region. These he describes^^ as made up of quartzites, mica schists, and 

 crystalline limestones and provisionally correlates them with the ISTasina 

 series. 



The intrusives of this belt of metamorphic rocks vary greatly in com- 

 position and texture, but are chiefly acidic and intermediate granular 

 rocks. All the earlier workers in this field assigned to the Basal Com- 

 plex^® a series of gneissoid rocks which were believed to have been folded 

 and metamorphosed previous to the deposition of the Birch creek or 

 Kasina series. In such parts of the region as have been studied in greater 

 detail this conclusion has been found to be erroneous, and it seems im- 

 probable that any rocks older than the ITasina have been found. Many 

 of the gneisses are found to be either sheared granites or quartz por- 

 phyries, which were intruded in the metamorphic sediments and subse- 

 quently infolded with them. These rocks, which occupy considerable 

 areas, have been termed the "Pelly gneiss" by McConnell, who has pointed 



^ Opus cited. See also "Geological Map of the Dominion of Canada." Western sheet, 

 no. 783. 



=■' Report on the Klondike gold Qeld. Geological Survey of Canada, Annual Report, 

 part B, vol. xiv, pp. 10B-23B. 



*» A reconnaissance in the White and Tanana River valleys. Twentieth Annual Re- 

 port. U. S. Geological Survey, part vii, pp. 465-467. 



^ Unpublished notes. 



^ .1. Keele : Report on Upper Stewart River region, Yukon. Geological Survey of Can- 

 ada, Ottawa, 1906, no. 943, p. 14c. 



^Geography and geology of Alaska. Professional paper no. 45, U. S. Geological Sur- 

 vey, pp. 208-210. 



