NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 247 



Character. — I.ight gray with some dark gray siliceous and arenace- 

 ous limestones, mainly in thick layers grouped in massive bands that 

 form great cliffs on Castle Mountain, Mount Bosworth and Mount 

 Stephen (see pis. 38, 39, 6"/, 70). A hand of bluish-gray, thin-bedded 

 limestone occurs towards the top, one about midway, and another 

 about 700 feet (213.4 m.) from the base on Mount Stephen. 



Thickness. — At Castle Mountain, 1,905 feet (580.6 m.) ; in the 

 Mount Bosworth .section, 22 miles (35.4 km.) northwest of Castle 

 Mountain, 2,728 feet (831.5 m.) ; and on Mount Stephen, about 8 

 miles (12.9 km.) southwest of Mount Bosworth, 2,840 feet (865.6 m.). 



Geographic di.<;iribution. — Castle Mountain and northwest, at Mount 

 Bosworth, and at Mount Stephen. It may extend to the southwest in 

 the " Main Range " southwest of the Continental Divide. I have 

 not seen it north of the Bow Valley, and it is absent in the Sififleur 

 River section. 



Fauna. — Middle Cambrian and related to the fauna of the subjacent 

 Stephen formation. Very few of the species are yet described. 



Observations. — The FJdon was deposited in the central portion of 

 the Cordilleran Geosyncline, where the greatest thickness of Cam- 

 brian sediment accumulated. Like the Goodsir of the Upper Cam- 

 brian, it was a relatively local deposit. 



Stephen Formation. Walcott, 1908* 



Type locality. — Northwest side of Mount Stephen, above Field. 



Character. — On Mount Stephen, calcareous, siliceous, and finely 

 arenaceous shales with more or less argillaceous matter, superjacent to 

 a thick band of bluish-black limestones in thin layers, which in turn 

 is underlain by a series of oolitic and gray limestones alternating with 

 bands of dolomitic limestone and a few l)ands of siliceous shale. 



Thickness. — At Mount Stephen, 712 feet (217 m.), at Mount 

 Bosworth, 640 feet (195. i m.), and at Castle Mountain, 366 feet 

 (111.6 m.). In the Sififleur River section, 36 miles (57.9 km.) north 

 of Mount Bosworth, the Murchison formation that occupies the 

 stratigraphic position of the Stephen is 497 feet (151.5 ni.) in 

 thickness. 



Geographic distribution. — Mount Stephen, Mount Bosworth to 

 Castle Mountain, a distance of about 31 miles (49.9 km.). It extends 

 southeast of the Bow Valley in the " Main Range," but how far is 

 unknown. To the north about 40 miles (64.4 km.) it is represented 



' Loc. cit. 



