220 INDEX TO THE STEATIGRAPHY OF NOETH AMEEICA. 



Eapid" on the Stikine. The general strike is northwest by southeast, but the direction and 

 angle of the dip is very varied and the beds are frequently much disturbed and twisted and 

 traversed by veins of quartz and calcite. There are probably frequent repetitions of the same 

 horizon, but the general arrangement may be synclinal, the dark shales and schists occupying 

 the higher position and being most abundant about the middle of this length of the river section. 

 Graptolites were found in the dark shales, particularly at a locality in a north bend of the 

 river, 11 miles westward in a direct hne from the mouth, and in appearance the whole series 

 is much hke that of the Cambrian calc schists and Cambro-SUurian graptohte shales of the 

 Backing Horse (Wapta) VaUey, west of the summit, on the hne of the Canadian Pacific Eailway. 



With reference to the geologic horizon, Lapworth ^^ reports : 



The graptohtes collected by Dr. Dawson from the Dease Eiver are identical with those 

 examined by me from the rocks of the Kicking Horse Pass some tim$ last year. 

 The species I notice in the Dease Eiver collection are — 



Diplograptus euglyphus (Lapworth). 

 Climacograptus comp. antiquus (Lapworth). 

 Cryptograptus tricornis (Carruthers) . 

 Glossograptus ciliatus (Emmons). 

 Didymograptus comp. Sagittarius (Hall). 

 New form allied to Coeuograptus. 



The graptolite-bearing rocks are clearly of about middle Ordovician age. They contain 

 forms which I would refer to the second or Black Eiver-Trenton period — that is, they are 

 newer than the Point Levis series and older than the Hudson and Utica groups. The associa- 

 tion of forms is such as we fin^ in Britain and western Europe, in the passage beds between 

 the Llandeilo and Caradoc hmestones. The rocks in Canada and New York with which these 

 Dease Eiver beds may best be compared are the Marsouin beds of the St. Lawrence VaUey 

 and the Normans Kill beds of New York. The Dease Eiver beds, perhaps, may be a little 

 older than these. 



These rocks are also apparently very similar to the graptolite-bearing slates 

 of the Alaska Range. 



O 15. SOUTHWEST COAST OF HTTDSON BAY. 



An isolated occurrence of limestone containing Trenton fossils near Fort' 

 Churchill is described by Tyrrell. *^^ The rocks had previously been observed by 

 Bell on Churchill and Nelson rivers and assigned to the Galena-Trenton horizon of 

 the Wisconsin Geological and Natural History Survey by Whiteaves,'^^ who also 

 recognized some probable upper Silurian or Devonian forms. 



In 1880. BelP« wrote: 



Geologically the basin of Hudsons Bay, excluding the western or Winnipeg division, lies 

 within the great Laurentian area of the Dominion. Cambro-SUurian rocks, resting almost 

 horizontally upon these, form an irregular border along the southwestern side of the bay, and 

 in the valleys of some of the rivers they extend inland from 100 to 200 miles. To the south 

 and west of James Bay the Cambro-Silurian [Ordovician] is overlain by Devonian rocks, which 

 here occupy a considerable area. 



Among the notes of a preliminary report on the region between Lake Winnipeg 

 and Hudson Bay, Low '*^ includes the following : 



The limestones of the Severn and Fawn rivers, as roughly determined from the fossils 

 collected, are not older than the Galena and may be as new as the Niagara; more investigation 

 is, however, required to fix their precise horizon. 



