SILVER LOCATIONS OF THUNDER BAY. 2l9 



the step-like outline (see Figure 3) so common in trap rocks, origina- 

 ting from fractures along these natural cleavage or separation planes. 

 This is the true explanation, it may be observed, of the step-like aspect 

 presented by trap rocks generally. The Lower Group (C-^) of the 

 copper-bearing strata of Lake Superior consists largely of beds of black 

 or dark-grey slate, and slaty quartzite, mixed here and there with 

 layers of anthracitic chert, and associated with subordinate beds of 

 dolomite, &c. ; whilst the Upper Group (C-) is made up principally of 

 white and red sandstone, light-coloured conglomerates and limestones, 

 and compact arenaceous marls, mostly of a pale yellowish-grey or pink 

 colour. The silver and copper-bearing veins of the north shore of 

 Lake Superior occur essentially in these altered Silurian strata : some 

 outcropping in the lower, and others in the upper group. 



2. The ShuniaJi Location: — This location lies about two miles due 

 north of Thunder Bay, immediately west of Current River. It in- 

 cludes three double lots, viz., 8 and 11, 9 and 12, and lO and 13, 

 comprising altogether 1,680 acres. Its central portion is situated, by 

 barometric measurement, at an elevation of 3l8 feet above the mean 

 level of the Bay. To the north of this central portion of the location, 

 the ground falls abruptly, and drains in great part into a small lake, 

 known as Spruce Lake, which occupies a portion of lot 9, and from 

 which a small creek flows through lots 10 and 13, and finally enters 

 Thunder Bay. A sufficient water supply, for washing and dressing 

 ores, could be obtained from this lake and creek, as well as from 

 Current River, if the location were subdivided, and worked by different 

 companies. These lots contain, moreover, an abundant supply of good 

 timber, suitable for mining purposes, and for fuel. 



The country-rock of the location consists of dark siliceous slates 

 belonging to the lower portion ot the Upper Copper-Bearing Series, 

 described above (6* 1), A broad and well-defined vein runs in a 

 nearly east and west direction through the southern portions of lots 8, 

 9 and 10, with a slight northern trend in the eastern part of its course. 

 Where it has been exposed, this vein averages from 20 to 23 feet in 

 width, and has a very slight underlie towards the north. In sinking 

 upon it, therefore, the shaft might be carried down to a very great 

 depth entirely within the substance of the vein itself Crystalline and 

 amethystine quartz, holding native silver in many places, caps the upper 

 part of the vein to the depth of a few feet,. whilst, under this, the gangue 

 or vein-stone consists essentially of calc spar. The vein presents the 

 usual brecciated structure exhibited by most of the Lake Superior veins, 



