ROCKS. OF BRULE LAKE AND EAGLE MOUNTAIN. Die 
Track Lake, in the southern part of T. 62, R. 1 W.; canoed this lake to the 
western end; portaged to Cascade River in Sec. 26, 'T.62, R.2 W.; and thence 
ascended Cascade River to its source in a series of small lakes, in the south- 
ern part of what would be T. 63, R. 2 W., if the country had been surveyed. 
They crossed in this ascent a series of distinctly bedded diabases and amyg- 
daloids, dipping southward at a low angle. The lake which forms the 
source of Cascade River lies in what would be about Sec. 2?, T. 63, R. 2 
W. Thence they took a W. N. W. course to Brulé Lake, which lies east 
and west, with a length and width respectively of about ten and two miles. 
The shores of the lake are bold and rocky, and exceedingly irregular in 
outline. The rocks assigned to the horizon now under description were 
found first on and about Eagle Mountain, which lies ten miles north and two 
west of the northeast corner of T. 62, R. 2 W., or somewhere about the 
S. E. 4 of Sec. 22, T. 63, R. 2 W. It rises abruptly on the east side of a 
small lake to a height of 450 feet, or to upwards of 1,500 feet above Lake 
Superior. 
The mountain is a bold mass of bright red rock, and from its summit 
may be seen numbers of other elevations composed of the same red rock. 
This rock is a granitic porphyry, and over most of the mountain presents 
an appearance closely resembling that of the second kind of red rock men- 
tioned as occurring at Duluth, while it is precisely similar to rocks seen 
cutting coarse gabbro at the same low horizon in the Bad River country of 
Wisconsin. It presents to the naked eye the appearance of being chiefly 
made up of small red feldspars, but there are areas which will not reflect 
any light. No other mineral is to be detected. Under the microscope the 
section presents precisely the same appearance as that of the Duluth rock, 
being made up of reddened orthoclases and matrix, the latter now so thor- 
oughly saturated with secondary quartz arranged in bunches of radiating 
lines, that its original nature is difficult to decide. The quartz also pene- 
trates some of the recognizable orthoclases, many of which are, however, 
without it. One or two particles of greenish hornblende were observable; 
minute black particles also occur. Near the top of the mountain a more 
dense kind than usual was noticed, which turned out to be a true felsitic por- 
phyry. No line of demarkation was noticed between the kinds. All about 
18 Ls 
