ANIMIKIE SLATES ON THE LUCILLE ISLANDS. 369 
the quartz-schists of the lower part of the Huronian Series at Penokee 
Gap; and the whole aspect is precisely that of the South Shore Huronian 
quartzites and quartz-schists of different horizons. A thin section of one of 
the more quartzose kinds showed it to be made up of angular quartz frag- 
ments, with a finer matrix, and some areas of quartz not so distinctly frag- 
mental. The strike and dip, obtained at a number of places in this vicinity 
from large dip-surfaces, range between N. 55° and 65° E. for the strike, and 
10° S. E. and 15° S. E. for the dip, the higher angles being the more common. 
The dikes on the east side of Wauswaugoning Bay run east and west, and 
are closely like those of Grand Portage Bay in character. The thin section 
of the rock of one of them showed the same peculiar rod-like magnetites 
seen in the Grand Portage dike-rock, but the rock is intensely altered, 
having all the augite turned into greenish material. 
The inner ones of the Lucille group of islands are again composed of 
the slates, dipping in the same way; the outer ones, as already said, being 
formed of the overlying Keweenawan diabases. On one island, however 
—the one called Brick Island on the United States Lake Survey chart— 
the rock is very peculiar. It is pink to bright brick-red in color, thinly 
and very distinctly stratified, dipping S. E. 83°, and is plainly part of the 
slate series. In the field this rock was taken to be simply a red variety of 
the usual quartzite seen all about on the adjoining coast and islands. But 
an inspection of the hand specimen shows that it is finely crystalline, while 
the thin section reveals a rock very close to those red rocks of the Kewee- 
naw Series which I have described under the names of augite-syenite and 
granitic porphyry; that is to say, it is a mass of feldspar crystals, satu- 
rated with secondary quartz arranged in the usual graphic form, while 
other larger quartz areas seem also to belong with the secondary quartz. 
Here and there is an augite crystal to complete the resemblance, and there 
is no trace of fragmental texture. 
Pigeon Point, the extreme eastern end of the Minnesota coast, shows 
the slates in fine exposure along its southern side, and with much the 
same characters as above described; 2. ¢., dark-gray to black, more or less 
highly argillaceous or clay-slate-like layers, alternating with others that are 
more quartzitic. Places, too, were noted on the point where a red rock, ap- 
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