8 



batholithic rocks on the west and are exposed in islands 

 in Chatham sound and in a strip along the mainland. 



Annotated Guide. 



vancouver to prince rupert. 



Gulf of Georgia. This long irregular arm of the 

 sea, separating the southern part of Vancouver island 

 from the mainland, is followed north-westward from 

 Vancouver to Valdez island, a distance of 150 miles (241 

 km.). The depression it occupies, usually from 12 to 20 

 miles (19 to 32 km.) in width, is attributed to crustal 

 warping in Tertiary times along the western border of 

 the Coast Range batholith. The depressed area is only 

 partially submerged, the more elevated portions still 

 rising above the surface as rocky islands. 



Texada island, 50 miles (80 km.) northwest of Van- 

 couver, the largest of these uncovered ridges, has a length 

 of 30 miles (48 km.) and is built largely of massive porphy- 

 rites, probably of Triassic age, intrusive into a limestone 

 referred on imperfect fossil evidence to the Carboniferous. 

 The coal-bearing Cretaceous strata of Vancouver island 

 formerly extended eastward across the gulf to Texada 

 island, but have been largely removed by erosion, and 

 are now only found in small isolated patches in sheltered 

 basins along the west coast. 



Texada island is well mineralized with deposits of 

 the contact metamorphic type, situated usually near small 

 dioritic or granitic stocks intruding the porphyrites and 

 limestones. The ore bodies in the Marble Bay mine on 

 the east coast, consisting mostly of bornite and chal- 

 copyrite in a garnet-epidote-augite gangue, have proved 

 very persistent, and the workings have now reached a 

 depth of 1,170 feet (356 m.) below the land surface and 

 1,120 feet (341 m.) below sea level. An important range 

 of magnetite lenses, some of large size, occur near the west 

 coast along irregular granite-limestone and porphyrite- 

 limestone contacts. 



Glacial deposits made up of two boulder clays separ- 

 ated by a thick band of sands, silts and gravels, interglacial 

 in age, form conspicuous banks in isolated areas on 

 Texada, Savary, and other islands in the gulf, and also 

 occur at intervals along both coasts. The beds in the 



