1 82 



The upper limit of this formation is not clearly defined 

 as it is transitional into the Lower Banff shale. 



Sawback Formation. — Underlying and conformable 

 with the Intermediate limestone is a series of massive and 

 thin-bedded, dolomitic limestone and shale, which Mc- 

 Connell has placed in the Cambrian. These form a 

 wedge-shaped band in the Sawback range and lie between 

 Mt. Hole-in-the-wall and Mt. Edith, with a broader 

 exposure along the north side of the Bow valley. It has 

 been possible to measure and estimate a thickness of 

 about 3,700 feet (1,128 m.) but the actual thickness is 

 believed to be much greater. Fossils have not yet been 

 found in this series. Since they differ lithologically 

 from the Cambrian beds in Castle mountain, which are 

 largely Middle Cambrian, and from the Cambrian in the 

 Bow range and to the west of this range, it is proposed 

 to call this series Sawback limestone. The age of the 

 formation is still in doubt but it is older than the Inter- 

 mediate limestone, which is definitely known to be Devon- 

 ian in age. These beds are lithologically closely related 

 to some of the Silurian beds in the Beaverfoot range to the 

 west. 



MISSISSIPPIAN. 



Lower Banff Limestone.* — This formation grades 

 into the Devonian limestone below, so that it is not possible 

 always to draw a sharp dividing line between these two 

 formations. It is quite clearly defined on its upper con- 

 tact, as the overlying formation is a shale. The beds 

 consist of massive-bedded, gray limestone which forms 

 steep escarpments wherever exposed on the slopes of a 

 mountain. 



This limestone forms the eastern cliffs of Cascade moun- 

 tain, and Mt. Rundle; and the steeper eastern slopes of 

 Sulphur mountain. Some beds are fossiliferous, and the 

 formation is characterized by numerous fossil-like dolomitic 

 segregations. Many of these resemble certain types of 

 bryozoan remains. 



Lower Banff Shale. — There are about 1,200 feet 

 (366 m.) of shale included in this formation. These 

 shales are black to dark gray in colour and weather brown. 



*Since Dr. Allan sent his MS. to press, Dr. H. W. Shimer has found that the fossils 

 recently collected in this limestone show it to be largely if not wholly of Devonian age. 



