no. 5 pre-devonian paleozoic formations 315 



Mount Stephen Section 



The section extends from the summit of the mountain down its 

 northeast and north slopes to the track of the Canadian Pacific Rail- 

 way at the tunnel east of Field. 



The massive siliceous dolomitic limestone (Eldon formation) form- 

 ing the upper portion of the mountain was not measured above the 

 upper bluish-gray limestone and shaly band. Its thickness is estimated 

 at 2,700+ feet (822.9+ m.). It is 2,728 feet (831.5 m.) thick on 

 Mount Bosworth. An attempt was made to measure the Cathedral 

 formation, but owing to step-faulting, the result is not satisfactory. 

 This formation has a thickness of i,59S feet (486.2 m.) on Mount 

 Bosworth so the measured and estimated thickness of 1,680 feet 

 (5 12. 1 m.) on Mount Stephen is given in the section. No attempt 

 was made to carry the section from Mount Stephen across to Mount 

 Dennis, owing to faulting, displacement, and alteration of the strata in 

 Mount Dennis. 



AlIDDLE CAMBRIAN 



Eldon Formation (Summit of Mountain) t- . a4 * 



'^ / beet Meters 



10. Massive-bedded, gray siliceous and dolomitic lime- 

 stone Estimate 2,700 + 822.9 + 



Total Eldon formation 2,700 + 822.9 + 



Stephen Formation 



la. Bluish-gray limestone with bands of dark siliceous shale 



in lower portion ^ 190 57.9 



Famta. — Middle Cambrian : the fossils are very poorly pre- 

 served, but the following have been recognized (57n) : 

 Protospongia (spicules) 

 Obolus cf. mcconnclli (Walcott) 

 Hyolithes, sp. 



Agnostus cf. montis Matthew 

 " Ptychoparia " sp. 

 Bathyuriscus (pygidium) 

 Ogygopsis (pygidium) 

 On Mount Bosworth a band of limestone 315 feet 

 (96 m.) similar to la occurs beneath the Eldon 

 formation, but a subjacent arenaceous limestone on 

 Mount Stephen is not present. The latter is probably a 

 faulted down block of the Eldon formation, the 

 fault probably cutting out the lower portion of la. 



I &. Calcareous and siliceous shales 150 45.7 



This shale is given the name of Ogygopsis shale 

 from its most predominating trilobite, O. klotzi. A 

 detailed description with its contained Middle Cam- 

 brian fauna follows this section. 



