NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 225 



matter, and a lower section of calcareous shales with interbedded 

 limestone in thick and thin layers. The sections vary in detail but 

 this general character of shales and limestone is found at nearly all 

 outcrops of the Mons over a wide area. 



Thickness. — In the Glacier Lake section. 1,480 feet (451.1 m.), 

 made up of calcareous shale, 235 feet (71.6 m.), massive gray lime- 

 stone, 740 feet (225.5 J^-)) si^d calcareous shale below, 505 feet 

 (153.9 ni.) thick. Thirty-three miles (53.1 km.) to the southeast, 

 at the head of the Clearwater River, the Mons has a thickness of 

 1,394 feet (424.8 m.), and at Ranger Canyon, 72 miles (115.8 km.) 

 southeast from Glacier Lake, it is 986 feet (300.5 m.) thick. It is 

 absent in the section of the Rocky Mountain front at Ghost River 

 24 miles (38.6 km.) east of Ranger Canyon. South of the Kicking 

 Horse Canyon in the Beaverfoot-Brisco-Stanford Range the Mons 

 thickens until at Sinclair Canyon it is about 3.826 feet (i. 166.2 m.). 

 At the southern end of the Stanford Range it thins out and does not 

 appear in the Sabine Mountain section. 



In my paper on the geological formations of the Beaverfoot-Brisco- 

 Stanford Range,^ I included the shales and interbedded limestone be- 

 neath the Silurian of Sabine Mountain in the Mons formation, but 

 with the inclusion of their fauna in the Upper Cambrian, the original 

 formation name Sabine is returned to and the Mons eliminated from 

 the Sabine Mountain section. 



Geographic distribution. — The typical Mons extends north from 

 the Glacier Lake area to the headwaters of the north Saskatchewan 

 drainage area, and presumably still farther north to where it disappears 

 or merges into the Chushina formation towards the Robson Peak 

 District. East of Glacier Lake it occurs in Mount Murchison and 

 Mount Sedgwick and in the clififs above the east side of the Sififleur 

 River, and thence southeast for about 60 miles (96.5 km.) to Bow 

 River Valley. South of Glacier Lake it is found in the lower Kicking 

 Horse Canyon east of Golden, and from there southeast nearly to 

 the south end of the Stanford Range. 



Stratigraphic relations. — The upper boundary of the Mons in the 

 Glacier Lake and Sawback Troughs as it occurs in the Glacier Lake 

 (B on map), Clearwater Canyon (E on map), and Fossil Mountain 

 (F on map) sections is clearly defined by the superjacent Sarbach 

 limestone, and in the Douglas Lake Canyon (G on map) and Ranger 

 Canyon (H on map) sections, by the Ghost River shale that is 

 immediately subjacent to the fossiliferous Middle Devonian Messines 



* Smithsonian Misc. Coll., Vol. 75, No. i, 1924, pp. 25-28. 



