NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 229 



Thickness. — In the Glacier Lake section, 1,700 feet (518.2 m.). 



Clearwater Canyon section, 33 miles (53.1 km) east-southeast of 

 Glacier Lake section, 1,050 feet (320 m.). 



Oyster Peak Ridge section, 18 miles (29 km.) south of Clearwater 

 Canyon section, 1,555 ^^^^ (474 m.). 



Ranger Canyon section, 21 miles (33.8 km.) south-southeast of 

 Oyster Peak Ridge section and 69 miles (iii km.) southeast of 

 Glacier Lake section, 1,470 feet (448.1 m.). 



Sinclair Canyon section, lOO miles (160.9 km.) south-southeast of 

 Glacier Lake section, 860 feet (262 m.) in thickness between the 

 Mons and a fault that cuts ofif the limestones referred to the Lyell. 



The thickness of the Lyell in the Sawback and Glacier Lake 

 Troughs is unusually uniform on the northwest-southeast axis of 

 the deposit, for a pre-Devonian formation deposited in the Cor- 

 dilleran Trough. In the Ghost River section, 25 miles (40.2 km.) to 

 the eastward (I on map), the Lyell is absent by non-deposition and 

 it is unknown to the southwest in the Bow and Goodsir Troughs, but it 

 is well developed in the Beaverfoot Trough. 



The Glacier Lake section is in the Glacier Lake Trough ; the 

 Clearwater Canyon, Fossil Mountain-Oyster Peak Ridge, and Ranger 

 Canyon sections are in the Sawback Trough, and the Sinclair section 

 is in the Beaverfoot Trough. 



Geographic distribution. — The Lyell limestones were seen as far 

 north as the head of Castleguard River 18 miles (28.9 km.) north 

 of Glacier Lake (B on map, pi. 26), and from there were traced 

 by several intermediate sections to the Ranger Canyon section (H on 

 map), a distance of nearly 85 miles (136.8 km.). It is not present 

 25 miles (40.2 km.) east of Ranger Canyon in the Ghost River sec- 

 tion (I on map) on the Rocky Mountain front, and I have not identi- 

 fied it to the south of the Sawback Range in the Assiniboine area, 

 but this may be due to my rapid reconnaissance over the area where 

 it may possil:)ly occur. To the west of the Continental Divide in British 

 Columbia it has not been recognized in the lower Kicking Horse 

 Canyon, but about 60 miles (96.5 km.) to the southeast in Sinclair 

 Canyon section, a similar limestone occurs beneath the Sabine forma- 

 tion that is referred to the Lyell. It also occurs along the Stanford 

 Range as far as Sabine Mountain 39 miles (62.8 km.) southeast of 

 Sinclair Canyon, where it is subjacent to the Sabine formation. 



StratigrapJiic relations. — The Lyell is conformably beneath the 

 Upper Cambrian Sabine formation in the Glacier Lake section, and 

 this relation is known to continue 69 miles (iii km.) to the south- 

 east to the Ranger Canyon section of the Sawback Range ; and also 



