197 

 Miles and From this point there is an excellent view 



Kilometres. - ■ *■ . 



or Mt. Stephen. Ihe base ot this mountain 

 is Lower Cambrian and it is capped by Bosworth 

 formation (Upper Cambrian). The Cathedral 

 formation extends to the top of the great 

 North shoulder. 



The Monarch mine is situated in Mt. Stephen 

 about 1,000 feet (305 m.) above the railway 

 in the Cathedral formation. The ore, con- 

 sisting of lead and zinc sulphides, is a replace- 

 ment deposit along a major and several minor 

 fissures. A concentrating mill, on the left 

 of the railway, has been recently constructed 

 and is separating about 80 tons of ore per 

 day. 



The second short tunnel passes through 

 the St. Piran quartzite in the shoulder of Mt. 

 Stephen. The railway follows along the slope 

 of the mountain, gradually approaching the 

 level of the valley floor. At Field it is only 

 10 feet (3 m.) above the river. 

 137 m. Field — Alt. 4,064 ft. (1,239 m -)- This 



219-4 km. railway divisional point is the gateway to 

 Yoho valley, Emerald lake and Ice River 

 valley. 



The famous trilobite fossil bed outcrops 

 in the Ogygopsis shale about 2,600 feet 

 (793 m.) above the railway on Mt. Stephen. 

 Walcott [6] has determined 32 species of 

 trilobita and brachiopoda from this lentile 

 of shale. This shale belongs to the Stephen 

 formation (Middle Cambrian.). 



Another fossil bed recently discovered by 

 Walcott occurs in the west slope of Mt. Field, 

 in the "Burgess shale," which also belongs 

 to the Stephen formation. This fossil bed is 

 reached by Burgess pass and is shown in an 

 illustration on page 177. From this shale 

 Walcott [7] has determined trilobita, brachi- 

 opoda, merostomata, malacostraca, annelids, 

 holothurians and medusae. 



West of Field the beds dip more steeply 

 to the west. A normal fault with the down- 

 throw on the west side, passes between Mt. 



