EARLY CAMBRIAN STRATIGRAPHY. 
105 
Montana , Phillipsburg District. — The Pre-Cambrian rocks 
are separated from a quartzite series correlated with the Flat- 
head by an unconformity involving angular discordance, yet 1 
“difficulty will often arise in exactly defining the limit between 
the Flathead and the Spokane (Pre-Cambrian). A sharp 
boundary can be drawn only where the unconformity is visible, 
or where the Flathead rests on shaly Spokane strata and the 
contact is marked by an abrupt lithologic change.” No fossils 
were obtained from the upper quartzite series (“Flathead”) 
and it can not be referred with certainty either to the Lower or 
Middle Cambrian. 
British Columbia , Elko. — The Pre-Cambrian rocks about 
two miles northwest of the town of Elko, British Columbia, are 
overlain without angular unconformity by a transitional sand- 
stone, sandy limestone, and shale series to which the name 
Burton formation has been applied. 2 The formation is readily 
divisible into a basal sandstone member 20 feet thick, and an 
upper shale member about 40 feet thick, but the faunas which 
have been secured from these beds all appear to be referable 
to the early Middle Cambrian. They are correlated with 
the Albertella fauna and, more or less tentatively, with the 
Crepicephalus zone of the Pioche formation. (See page 126 and 
the section on the Burton formation, pages 125-128). 
British Columbia and Alberta , Mount Bosworth Section and 
Bow River District. — The base of the section along the main line 
of the Canadian Pacific railway in British Columbia and Alberta 
is composed of a clastic series to which McConnell early 3 applied 
the term Bow River series or Bow River group. It is several 
thousand feet thick and has been recently described 4 as including 
2,500 feet of Pre-Cambrian at the base. Frequent variations in 
the sedimentation and the presence of conglomerates at many 
places in the section, 5 however, complicate the proposed separa- 
tion. The Cambrian rocks of the Bow River district have 
1 Emmons and Calkins: Prof. Paper, U. S. Geol. Survey, No. 78, 1913, p. 51. 
2 Schofield: Geol. Surv. Can., Museum Bull. No. 2, 1914, p. 82. 
3 Ann. Kept. Geol. and Nat. Hist. Survey Canada for 1886, Part D, 1887, pp. 29 
D-30 D. 
* Walcott: Smithsonian Misc. Coll., vol. 53, No. 7, 1910, p. 428. 
5 McConnell: Ann. Rept. Geol. and Nat. Hist. Survey Canada for 1886, Part D, 
1887, p. 30 D; and Daly: Geol. Survey Canada, Memoir No. 38, 1912, p. 176. 
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