NO. 4 PRE-DEVONIAN SEDIMENTATION 167 



the latter are subjacent to the hmestones of the Uzarkiaii, Alons 

 formation, and they, in turn to the Hmestones of the r)rdovician 

 (Canadian) Sarbach formation, indicating strongly that they were 

 deposited under similar conditions. The presence of diagnostic 

 faunules in the Sarbach, Mons, and Sabine formations proves that 

 there was an open seaway from Sabine Mountain to Glacier Lake, a 

 distance of 130 miles (209.2 km.). None of these faunules or a simi- 

 lar succession of formations has been recorded east or northeast of 

 the Beaverfoot Trough for a distance of 38 miles (61.1 km.) or until 

 the southwestern side of the Sawback Trough east of the great Castle 

 Mountain fault is reached. 



The Silurian, Brisco and Beaverfoot formations and Ordovician 

 (Canadian) Glenogle graptolite shales extend from the southern end 

 of the Stanford Range (O on map) north-northwest to the Kicking 

 Horse Canyon (/ on map), but they have not been reported from 

 beyond the Kicking Horse drainage area. They should be looked for 

 in the Blaeberry River and Bush River drainage areas, along the 

 western slopes of the Continental Divide. 



The character of the folding and faulting to which the strata of 

 the Beaverfoot Trough have been subjected is shown by the sections 

 of McConnell * and Allan ^ of the northern portion of the Beaverfoot 

 Range and the Walcott section of the Brisco-Stanford Range at 

 Sinclair Canyon, 55 miles (88.5 km.) southeast.' 



SAWBACK TROUGH 



Plate 25 



The Bow Trough appears to have shallowed towards the close of 

 Middle Cambrian time, so that the shallow water Arctomys formation 

 and the calcareous sediments of the Sullivan were almost excluded 

 from it except in the depression we are now designating as the Saw- 

 back Trough. This trough extended from the Glacier Lake Trough 

 {D on map), with which it was connected by an open seaway, south- 

 east as far at least as the Bow Valley {H on map). 



The Sawback Trotigh was at first a narrow depression or down- 

 warp in the bottom of the Bow Trough that accompanied the slight 



' Rept. Gcol. Surv. Canada, Rcpt. D., Vol. II for 1886 (1887). Section p. 42 D. 



' Geol. Surv. Canada, Guide Book No. 8, Pt. II. Transcontinental Excursion 

 C, I, 1913. Structure section. 



* Smithsonian Misc. Coll., Vol. 75, No. i, p. 10, fig. 2. 



The anticline of the eastern end of this section is probably broken by faults 

 or possibly by a synclinal fold, or both faults and fold. Such a structure is 

 suggested at the head of Dry Gulch a little south of Sinclair Canvon. 



