STRATIGRAPHY ALONG THE ROCKY MOUNTAIN TRENCH 369 



In regard to Daly's fifth point concerning the Selkirk series, 

 recent evidence shows that the age of the series is very uncertain,^ 

 As stated above, Daly places the dividing Hne between the Cam- 

 brian and the pre- Cambrian in the Ross quartzite, because of 

 Kthological resemblances of the sequence of formations in the 

 Canadian Rockies and the Selkirks, but the discovery of upper 

 Paleozoic fossils in the Laurie formation, which underlies the Ross 

 quartzite formation by 12,650 feet and is separated from it by the 

 Nakimu limestone and the Cougar quartzite, disproves this con- 

 clusion. 



A recent observation further complicates the situation.^ The 

 Cougar quartzite was found underlying the Upper Cambrian 



Devonian 



Upper Richmond 



Shale and Quartzite 

 thin-bedded 

 limestone 



Massive gray Quartz- Shale and 

 limestone ite thin-bedded 



limestone 



Fig. 3. — Section at Harrogate 



shales and limestones on the west side of the trench at Golden, 

 and, while a detailed study of the contact was not made, it appears 

 probable that there was at least no angular unconformity separating 

 the two formations. Therefore one discovery places the Cougar 

 formation above upper Paleozoic fossils and the other places it 

 below the Upper Cambrian. It seems probable that the series in 

 the Purcell Range is not of the same age as that in the Selkirks, a 

 conclusion which seems more likely when it is considered that 

 the section in the Purcell Range exhibits only a part of two of the 

 formations which are present also in the Selkirks (Fig. 3). 



I L. D. Burling, Bull. Geol. Soc. Am., Vol. XXIX, p. 146. 

 ^ F. P. Shepard, Jour. Geol, Vol. XXX (1922), p. 146. 



