460 Cambro-Ordovician Section in the Beaverfoot Range. 



(5) The Mount Bosworth section was first described ^ as overlain 

 by the Ordovician, but a later visit^ proved the presence in the upper- 

 most beds of Cambrian fossils and true Ordovician was placed 

 several thousand feet higher in the section.^ 



(6) The Bosworth formation is of special interest as the locus of 

 the earliest discovered evidence of profound disconformity between 

 the Middle Cambrian and the Upper Cambrian. The contact between 

 the Middle Cambrian Eldon and the overlying Bosworth with its 

 ripple marks, mud cracks, and casts of salt crystals has been 

 described."* Since these papers were written the Bosworth has been 

 identified in the Sawback Eange, west of Banff, and in the vicinity 

 of White Man's Pass, south of Mount Assiniboine, in each of which 

 localities it preserves its peculiarities of sedimentation and character. 



(7) The Stephen formation is the horizon which has yielded the 

 remarkable Ogygopsis shale and Burgess shale faunas, assemblages 

 which occupy very fine-grained lenses within its boundaries in Mounts 

 Stephen and Field respectively. As has already been described,^ 

 the formation loses this fine-grained character as it is followed 

 eastward, and in Castle Mountain, just west of the Sawback Eange, 

 it is coarsely ripple-marked and mud-cracked. It may very well 

 be absent as a formation in the Sawback Range, 



(8) This is the formation carrying the Albertella fauna, whose 

 stratigraphic position has finally become established,'' and whose 

 fauna has been figured.'' It will be of interest to record here that 

 as the Albertella shale is followed southward past Mount Temple 

 into the Mount Assiniboine region, and northward into the Mount 

 Robson region, it becomes progressively more calcareous, and that 

 at Mount Robson and Mount Assiniboine the horizon is represented 

 by a calcareous Albertella horizon in the general limestone shale 

 section of the Middle Cambrian. 



Dr. Walcott believes ® that the " stratigraphic position of the 

 Mount Whyte justifies its classification with the Lower Cambrian ", 

 and, I believe, that the stratigraphic relations ^ near the base of the 

 formation justify the transfer of its major and upper portion to the 

 Middle Cambrian. Wherever the line is drawn we both seem to be 



1 Walcott, Smithsonian Misc. Coll., vol. liii, No. 5, 1908, p. 204. 



2 Allan and Burling, Walcott, id,., vol. Ivii, No. 7, 1912, p. 229. 



3 Allan, Summ. Bep. Geol. Sun: Canada for 1911, 1912, pp. 171-81 ; 

 BurKng, Journ. Washington Acad. Sci., vol. ii, 1912, p. 357. 



■* Burling, " Shallow Water Deposition in the Cambrian of the Canadian 

 Cordillera " : Ottawa Naturalist, vol. xxix, 1915, pp. 87-8 ; " Down-warping 

 along Joint Planes at the Close of the Niagaran and Acadian " : Journ. Geol, 

 vol. XXV, 1917, pp. 145-9. 



■^ Burling, Ottawa Naturalist, vol. xxix, 1915, pp. 87-8. 



^ Burling, " The Albertella Fauna Located in the Middle Cambrian of 

 British Columbia and Alberta " : Amer. Joxirn. Sci., vol. xlii, 1916, pp. 469-72. 



"• Walcott, " Fauna of the Mount Whyte Formation " : Smithsonian Misc. 

 Coll., vol. Ixvii, No. 3, 1917, pp. 61-114. 



® Science, vol. xlv, 1907, p. 355. 



3 Summ. Rep. Geol. Surv. Canada for 1915, 1916, p. 100. 



