November 19, 1914. 
Canada 
Geological Survey 
Museum Bulletin No. 4 
GEOLOGICAL SERIES, No. 20. 
The Crowsnest Volcanics. 
By J. D. Mackenzie. 
INTRODUCTION. 
GENERAL STATEMENT. 
The Crowsnest volcanics are a series of tuffs and agglom- 
erates, with exceptionally occurring flow rocks, that are found 
in the eastern Rocky mountains of Alberta, in the general 
vicinity of the Crowsnest pass. 
During the summer of 1912, the writer was engaged in the 
geologic mapping of the southern extension of the Frank- 
B lairmore-Coleman coal fields, in southwest Alberta, and had 
frequent opportunities to study the field relations of these 
volcanics. Specimens of the more typical varieties of the rocks 
were collected, and have since been studied petrographically, 
the results forming a part of this paper. 
Personal observation has been confined to the valley of the 
Southfork river and adjacent exposures, and visits to some 
outcrops on York creek, near Blairmore. The following ob- 
servations and remarks thus apply more particularly to the 
southern exposures of the formation; but descriptions of the 
more northern occurrences by Leach and Dawson show that the 
characteristics of the volcanics are essentially as described 
below. Owing to the press of other matters in the field not as 
much time could be devoted to the study of these pyroclastic 
rocks as is desirable, but the facts that have been gained are 
