204 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



MOUNT BOSWORTH SECTION 



Mount Bosworth section, north of Hector, British Columbia, on 

 the Continental Divide, north of the Canadian Pacific Railway. 



The summit of the section is on the west spur (Sherbrooke ridge) 

 of Mount Bosworth overlooking Sherbrooke Lake. The highest 

 beds are on the south summit of the ridge, and from their lithologic 

 character and the finding of obscure fossils that suggest Ophileta 

 of the Lower Ordovician the upper no feet of strata are tentatively- 

 referred to the Ordovician system. The strata near the summit are 

 much broken up owing to a fault line that crosses the ridge. 



ORDOVICIAN 



fauna (in oolitic layers) : 

 Agnostiis, sp. undt. 



Feet 



I. Massive bedded gray and bluish gray arenaceous limestone, 

 with thin layers, irregular stringers, and nodules of dark 

 chert no 



UPPER CAMBRIAN 



SHERBROOKE FORMATION [Walcott, 1908a, p. 2] : 



I. Massive bedded, bluish gray limestone, with some cherty matter 

 in the form of small nodules and stringers; also irregular 

 partings and fillings of annelid borings by gray dolomitic 

 limestone weathering buff I75 



Fauna : 



Annelid borings and trails. 

 Fragments of undeterminable trilobites. 



2a. Gray oolitic limestone in thick layers, with bluish banded lime- 

 stone intercalated at irregular intervals. The banded ap- 

 pearance of the nonoolitic layers is owing to the bufif weath- 

 ering of the thin dolomitic layers 190 



Fauna (Upper Cambrian facies) : 

 Crepicephalus. 

 Pterocephalus ? 

 Ptychoparia. 



2b. Greenish drab and gray siliceous shales with interbedded oolitic 

 limestone in bands of layers froin 6 inches to 4 feet thick; 

 also a few bands of thick-bedded, bluish gray limestone that 

 breaks up into shaly limestone on weathering 335 



Fauna (in green shales near summit) : 

 Lingulella isse (Walcott) [1905, P- 33o]. 



Illcenurus. 

 Ptychoparia. 



