NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 211 



conformable to both the superjacent Devonian and the subjacent 

 Sarbach, but it is to be noted that a great thickness of strata is 

 present at Ranger Canyon, beneath the shale band, that is not present 

 to the eastward at Ghost River, and that presumably was not deposited 

 there. Again, 15 miles (24.1 km.) northwest of Ranger Brook in 

 the Douglas Lake Canyon section (G on map) and on the general 

 northwest strike of the Cordilleran geosyncline, a band of bufif-colored 

 arenaceous shale 10 feet (3 m.) in thickness occurs between the 

 Devonian and the subjacent Sarbach, but in a section on the eastern 

 slope of Fossil Mountain (F on map) 38 miles (61 km.) northwest 

 of the Ghost River section and 4 miles (6.4 km.) west of the Douglas 

 Lake Canyon section, a series of thin layers of magnesian limestone 

 with interbedded thin layers of chert 35 feet (10.7 m.) thick, that 

 stratigraphically occupies the position of the (ihost River formation, 

 occurs beneath the Middle Devonian Messines limestones and above 

 the Skoki formation. 



SILURIAN 



The Silurian is represented on the western side of the Beaverfoot- 

 Brisco-Stanford Range by the limestones of the Brisco and Beaver- 

 foot formations and the Wonah quartzite, all of which were deposited 

 in the Beaverfoot Trough and as far as known not elsewhere in the 

 area of the Cordilleran Geosyncline now under consideration. The 

 base of the Silurian is definitely marked by the Wonah quartzite which 

 records the advance of the Silurian sea into the Beaverfoot Trough. 



I have given my opinion on including the Beaverfoot formation, 

 with its " Richmond " fauna, in the vSilurian rather than in the Ordo- 

 vician ' and have nothing more to add to it here as all the evidence 

 from the Cordilleran area appears to be strongly, and to me con- 

 clusively, in favor of referring the Beaverfoot to the Silurian. 



Mr. J. F. Walker ^ studied the Brisco and Beaverfoot formations 

 in the Stanford Range of the Windermere map area and concluded 

 that the two formations are transitional into each other, and refers 

 to them as the " Beaverfoot-Brisco formations (Richmond and 

 Silurian),"^ adding that "the Richmond is transitional into the 

 Silurian." * 



^ Smithsonian Misc. Coll., Vol. 75, No. i, 1924, p. 41. 



" Geol. Surv. Canada, Mem. No. 148, Geology and Mineral Deposits of 

 Windermere Map Area, 1926, pp. 31-34. 

 'Idem, p. 31. 

 * Idem, p. ^2. 

 3 



