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island, trends N. 55 W. The entire island is 290 miles 

 (470 km.) long and 50 to 80 miles (80 to 130 km.) wide, the 

 total area being about 14,000 square miles (36,000 sq. km.). 

 It is, as stated, separated from the Coast range of the 

 mainland by the submerged northern end of the Pacific 

 Coast downfold, which is occupied from south to north 

 by Haro, Georgia, Johnstone, and Broughton straits 

 and Queen Charlotte sound. It is separated from the 

 mainland to the south, that is from the Olympic mountains 

 of Washington, by a smaller transverse downfold, striking 

 about N. 70 W., now occupied by the Strait of Juan de 

 Fuca. 



Vancouver island is composed of deformed metamorphic, 

 volcanic and sedimentary rocks, intruded and replaced 

 by numerous irregular bodies of granitic rocks, and fringed 

 along both coasts with fragmental sediments, which rest 

 unconformably upon the metamorphic and granitic rocks. 

 The metamorphic rocks are largely of lower Mesozoic 

 age, presumably upper Triassic and lower Jurassic, but 

 they may include some Palseozoic members. Apparently 

 the oldest rocks, considered provisionally as of late Palseozoic 

 (Cariboniferous) age, are a series of slates and quartzose 

 schists, with some fragmental volcanic members. This 

 series extends across the southern end of the island and 

 is called the Leech river formation. 



The lower Mesozoic rocks comprise the larger part of 

 Vancouver island, and constitute the Vancouver group. 

 They consist chiefly of metamorphosed basic volcanics, 

 principally meta-andesites, the Vancouver volcanics. 

 Certain schistose and more salic volcanic rocks are ap- 

 parently interbedded with the Leech river formation, 

 but the typical meta-andesites, although separated from 

 the Leech river formation largely by faults, are apparently 

 younger and unconformable. Associated with the Van- 

 couver meta-andesites and occurring chiefly in small 

 intercalated lentils, is a formation of limestones called 

 the Sutton formation. Besides the limestones, there 

 is associated with the meta-volcanics a series, of stratified 

 slaty and cherty rocks, the Sicker series, composed partly 

 of volcanic material. These rocks and their associated 

 volcanics have been greatly metamorphosed and converted 

 into schists. 



All of the above mentioned rocks are intruded and partly 

 replaced by batholithic and dyke (minor intrusive) rocks. 



