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COPPER RANGE OF DOUGLAS COUNTY, WISCONSIN. 20 
colored, slaty layers occur between the reddish, shaly layers. In the course of 75 feet, 
the exposure begins to show evidences of horizontal bedding with a transverse slaty 
cleavage, as shown in the cut. Beyond this, the layers are broken and dip somewhat, 
and only one or two of them show the slaty cleavage. After another bed of slate 
and shale, as shown, and attempts at slaty cleavage, the rock becomes evenly bedded 
and horizontal. It is fine-grained, and more aluminous than is usual with the Lake 
Superior sandstones. There are no conglomerates, breccias, or thick layers of coarse 
sandstone seen in the vicinity. 
Eastward from Middle river, neither the copper-bearing rocks nor sandstones are 
exposed for a distance of about 7 miles. Between Middle river and the high ground, 
locally known as the Brulé range, the country is quite level, somewhat swampy, and has 
an elevation of about 400 feet. The Brulé range, commencing in T. 47, R.11 W., attains 
an altitude on the broad summit of about 540 feet. Towards the western end are two 
or three small exposures of fine-grained, dark-gray diabase. On Sec. 29, T. 48, R. 10 
W., is an exposure of diabase, fine conglomerate and sandstone, very similar to that 
described as occurring on the Aminicon river. In the NE. 4 of Sec. 28, at the falls 
of a small stream, is an exposure of dark-gray amygdaloidal diabase, a few feet in 
height, and 10 or 12 yards long. A test pit was sunk here on what appears to be a 
small quartz and epidote vein bearing altered amygdaloid, by the North American 
Fur Company, in 1847. A small quantity of iron pyrites and copper carbonate were 
observed with the débris. The dip here is 30° §. 40° E. 
No exposures are found from here to the Percival mining location, a mile to the 
east. At this location the natural exposures are small and few in number, but the 
underlying rock is lightly covered with drift, which may be easily removed. The rock 
is usually a dark greenish-gray amygdaloidal diabase, carrying in places shot and 
nugget copper. The bedding is not very distinct. At the wagon-bridge across the 
Brulé, on See. 23, and occasionally along the banks of the stream for a half mile 
below, there outcrop low ledges of a dark-colored amygdaloidal diabase. A quarter 
of a mile below these exposures there are low ledges of nearly horizontal, reddish, 
heavily-bedded sandstone in the banks of the stream. Similar sandstones are found 
along the banks and in the channel, forming numerous rapids nearly to the mouth of 
the river. No exposures were found on the steep sides of the valley, although, in the 
vicinity of the sandstones and crystalline rocks, it is over 200 feet deep, and not half 
a mile across from summit to summit. On the northeast quarter of Sec. 25, a short 
distance north of the Bayfield road, there is a very prominent and high exposure, form- 
ing the western end of that portion of the range east of the Brulé river. The summit 
of the bare, bald cliff is 301 feet above the bridge across the stream at its foot, or 553 
feet above Lake Superior. 
* * * * * * * * * 
'From the altitudes, trend, and general appearance of the ridges or abrupt ele- 
vations to the south, a few miles from the lake shore, in Bayfield county, we should 
expect to find crystalline rock exposures, occasionally, as in Douglas county. The 
streams are numerous, and, like those to the west, cut deep and narrow valleys 
through the drift, near the abrupt ascent of the country to the south, and nearly all 
expose small ledges of horizontal, reddish Lake Superior sandstone, but none of them 
appear to have uncovered the Keweenawan rocks. In the southwest part of T. 50, R. 
1Geology of Wisconsin, Vol. III, p. 348. 
17L8 
