28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



The section was here followed south along the southwest face of Sabine 

 Mountain to where the rise in dip brought lower beds above the debris slope, 

 and where at the southwest angle of the mountain the section of the Mons is 

 exposed from the disconformity at the base of the Silurian to the contact with 

 a massive magnesian limestone below, which is assumed to be the equivalent 

 of the Lyell of the Glacier Lake section. Feet Meters 



ig. Just below the limestone of if, shale with interbedded 

 stringers and thin layers and flat nodules of limestone 

 appear which contain the Briscoia fauna, which also 

 occurs in thin pieces of limestone on the debris slope 



of the section of if above 170 51.8 



Strike N. 25° W., Dip 50° N. 65° E. 

 Fauna. — ^Fragments of Briscoia cf. sinclaircnsis Walcott 

 similar to those of locality 17s were found in the upper 

 portion of ig. (Locality 2ip.) 

 ih. Buff colored arenaceous shale weathering reddish buff 

 brown with a few interbedded layers of gray limestone. 

 The shales become slightly coarser at 200 feet (60. 9 m.) 



down 275 83.8 



Fauna. — A sftiall fauna occurs in a thin interbedded layer 

 of soft gray limestone 54 feet (16.5 m.) below the 

 summit of ih that contains the following species 

 (locality I7v) : 



Obolus cf. Icda Walcott 

 Acrotreta sp. undt. 

 Agnostus sp. 

 Ptychaspis sp. 

 Ellipsocephalus ? sp. 



Total Mons 742 226.1 



The distinction between ig and ih is a gradual decrease of limestone and 

 argillaceous shale and an increase of fine arenaceous sediment. As seen in 

 cliffs there is very little change indicated except by the color. 



upper cambrian 

 Lyell ? Formation : t- < ut ^ 



Feet Meters 



The Mons shales are superjacent to an outcrop of thick- 

 bedded, semi-crystalline, gray magnesian limestone that 

 I have referred to the Upper Cambrian and correlated 

 with the Lyell formation of the Saskatchewan-Glacier 

 Lake area 139 miles (223.6 km.) to the north.' 



Thickness 400 121.9 



A fault here cuts across the lower southwest end of the mountain (pi. 7, 

 fig. 2) that has displaced a mass of bedded magnesian limestone so that it 

 forms a high knoll with a southwestward facing cHff the base of which is 

 nearly on the plain of Canal Flats. The upper 300 feet (91.4 m.) of this cliff 

 and knoll is formed of thick beds of limestone similar to those beneath the 



' See p. 39. 



