166 Copper Mines of Lake Superior. (April, 
an irregularly-shaped body, as much as two miles wide 
where excavated out of the low-lying sandstone, but taper- 
ing rapidly where the high, bluff cliffs of the trap beds 
of the copper-bearing series confine it. While still in the 
low-lying horizontal sandstone, it throws off towards the 
north-east a long arm, which expands into Torch Lake, 
a considerable body of water whose north-west shore almost 
defines the line of conta¢t between the horizontal sandstone 
and the steeply-tilted copper-bearing rocks. 
As the steamer enters the narrows, and there come into 
view the towns of Hancock and Houghton facing one 
another on the opposite banks, the large mills on the lake 
shore, and the mine buildings and tramways on the heights 
above, the contrast between:the modes of activity and the 
aims of civilised man, and of the Indians, with whom the 
traveller, if he has been long on the lake, must have come 
into close contact, strikes the mind very forcibly. 
Where the copper-bearing rocks are exposed by the deep 
fissures, whose bottom is occupied by Portage Lake, the 
width of the range is seven miles, and the beds dip at 
an angle of 54° to the North West. They consist of traps of 
varying degrees of compactness and shades of colours, 
interstratified with conglomerates and sandstones. 
According to Macfarlane, ‘“‘ the constituent of the traps of 
the Portage Lake District are principally felspar of the 
labradorite species, and chlorite of a species allied to 
delessite, with which are found occasionally mica, small 
quantities of magnetite, and perhaps of augite and horn- 
blende.”* He considers the characteristic trap of the region 
to consist of :— 
Delessite  scighivce “sis se: eaeioeee 
Labradorite 2%) ais vale eee 
PYLOREME 6 Pa ena uae eee ee 
Manette «iP Yes apa ea, aus 
100°00 
The mines in the immediate vicinity of the Lake are on 
the amygdaloidal trap. Many have been opened both on 
the north and south shores, but those only on the Pewabic 
lode—the Quincy, Pewabic, and Franklin mines—have 
returned profit to their shareholders. Of these three, the 
best worked, and therefore most successful, is and has been 
the Quincy, and we shall therefore describe it as being a 
typical, though the best example, of its class. 
* Geological Survey of Canada, 1866, page 158. 
