32 



Mile 183-5. — The railway, which, since leaving Mile 

 178, has followed a terraced fiat south of the river ap- 

 proaches and joins it here, and for some miles skirts closely 

 the edge of the wild canyon in which it is enclosed. The 

 walls of the canyon, usually over 200 feet (60-9 m.) in 

 height, show almost continuous exposures of the undulating 

 and in places crumpled and broken, strata of the Hazelton 

 formation. Boulder clays in heavy ridgy sections overlie 

 the older rocks, and are pierced in three placed by tunnels. 



Mile 186. — A boulder clay plateau, 75 feet (22-8 m.) 

 in height above the grade of the railway, and 300 feet 

 (91-4 m.) above the river level, is pierced by a tunnel 

 2,016 feet (614-4 m -) m length. Southwest of the tunnel, 

 the deep, winding, rocky gorge of the Bulkley is seen to 

 advantage from the railway grade. 



Mile 188. — A deep cut exposes the boulder clay at 

 this point. Boulder clays often associated with sands, 

 clays and gravels are prominent in most of the sections 

 along this portion of the valley. 



Mile 190-9. — Here the deep valley of Mud creek, 

 sunk through boulder clay, is spanned by a high bridge. 



Mile 193. — Long sections of greyish coarse tuffs and 

 volcanic breccias holding numerous rounded andesitic 

 bombs, occur at this point and are underlaid in places by 

 the dark tufaceous sandstones characteristic of the Hazel- 

 ton group. 



Mile 193-5. — The coarse grey fragmentals are cut by 

 an altered andesitic dyke 120 feet (36-5 m.) in width. 

 The dyke probably belongs to the same period of vulcanism 

 as the band of ejectamenta it cuts. 



Mile 193-9. — The tuffs are overlaid by a massive 

 band of green andesite showing brecciation in places. 



Mile 195-9. — North of Porphyry creek the green 

 andesitic flow rocks are cut by a white, yellow weathering, 

 altered intrusive filled with pyrite. This rock represents 

 a contact phase occurring at the termination of a large 

 granodiorite stock which extends to the northeast. 



Mile 196-3. — Sections of green andesite, brecciated 

 in places and occasionally holding greenstone fragments, 

 are exposed at this point. 



Mile 198-9. — Boulder creek is crossed on a high 

 bridge. 



Mile 202-1. — The beds of the Skeena formation 

 (lower Cretaceous) occupy a basin extending along the 



