SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



17 



light gray limestone extended in all directions until near the edge of 

 the sloping cliffs above the canyon valley, where long narrow strips 

 of trees and grass covered spaces occurred between the north and 

 south ledges. Another approach was made from the south side of 

 the brook, and an outcrop of a few thin layers of bluish-gray lime- 

 stone was encountered on a small, rounded, glaciated ridge of the 



Fig. 10. — Camp on north slope of Burgess Pass, B. C, from which the 

 Burgess shale quarry was worked for several years. This is a typical camp 

 where grass for horses, firewood and water are close at hand. (C. D. 

 Walcott, 1924.) 



magnesian Lyell limestone. These bluish-gray layers were interbedded 

 in the Lyell, and contained fragments of Upper Cambrian trilobites. 

 Returning another day, the thin band of bluish-gray limestone was 

 traced to the brook and in a small narrow canyon two bands of shale 

 and bluish-gray limestone were found a little lower in the section. 

 The lowest band was rich in fragments of trilobites that later were 

 found to be closely related to Upper Cambrian Franconia trilobites 



