4 70 



L. I). Burling — The Albertella Fauna. 



years in which search has been prosecuted is due to the fact 

 that its reference to the Lower Cambrian led vis largely to con- 

 line our efforts to the series of thin beds underlying the Cathe- 

 dral formation. 



The fauna actually occurs in a 7-foot band of shale which 

 interrupts the sedimentation of the massive limestones of this 

 Middle Cambrian formation 375 feet above its base. The out- 

 crop of this shale, to which the name of Albertella shale mem- 



Fig. 2. 



Fig. 2. Described species of American Albertellas. 



A. Albertella bosworthi Walcott (British Columbia). 



B. Albertella Helena Walcott (Montana). (After Walcott.) 



C. Albertella Helena Walcott (British Columbia). 



ber of the Cathedral formation is bereby applied, has a hori- 

 zontal extent of several hundred feet on the east and northeast 

 face of Mount Bosworth at an elevation of about 8000 feet 

 (see fig. 1). Mount Bosworth lies on the continental divide 

 just north of the main line of the Canadian Pacific Railway 

 between Alberta and British Columbia. The relations of the 

 Albertella shale to the over- and underlying beds is given in 

 the following section of the lower portion of the Mount Bos- 

 worth and Castle Mountain sections: 





Formations 



Mount 

 Bosworth 



Castle Mountain, 

 20 miles southeast 



Middle Cambrian 



Eldon. 



Stephen 



feet 

 400 



775 



7 



375 



250 



feet 

 315 

 565 



10 

 200 

 200 



Cathedral (upper) .. 



Albertella shale 



Cathedral (lower) .. 

 Mount Why te 



Lower Cambrian (St. Piran) 



