THE BOHEMIAN RANGE. 183 
empties, and again in Sec. 30, T. 58, R. 27 W., still further east. All of 
these exposures cannot well belong to the same belt, and it would appear 
probable that the Mount Houghton rock, along with some smaller elevations 
leading off from it in an easterly direction, belong with the more easterly 
of the exposures on the coast, while the Bare Hills belong to another belt. 
These red rocks Foster and Whitney regarded as sandstones baked by 
the heat of the intrusive rock of the Bohemian Range, but they are plainly 
enough but one phase of the quartziferous porphyries and felsites, which I 
have heretofore recognized as characterizing the Keweenaw Series through- 
out its extent. They show no trace of fragmental origin, either microsco- 
pically or macroscopically; and if the other porphyries are eruptive, these 
are as well.’ 
Westward from Mount Houghton I have not seen anything of this 
porphyry belt, unless—as is very probable—a quartziferous porphyry on 
the line of the railroad from the Calumet mine to Torch Lake, in See. 36, 
T. 56, R. 33 W., should belong here. On the geological map of Keweenaw 
Point, by Stevens and Hill, this porphyry belt is indicated as far west as 
the eastern part of range 32. 
South of the Mount Houghton porphyry belt, for a width of from 
one-half to three-fourths mile, the prevailing rocks are typical fine-grained 
diabases with the usual pseud-amygdaloids and true amygdaloids, which 
neither in the specimen nor in the thin section present any differences 
from the more northern diabases. With these prevailing kinds are sev- 
eral belts of the typically luster-mottled rocks which Pumpelly has called 
melaphyrs, and which are here very rich in much altered olivine, and are 
here, as always, sharply distinguished, both macroscopically and micro- 
scopically, from the associated olivine-bearing diabases. There are also one 
or more belts of typical fine-grained diabase of the ashbed type, and two 
or more porphyry-conglomerates. All of these rocks may be seen well 
exposed on the road from Lac La Belle to the Delaware mine, especially 
in the vicinity of the stream in the S. E. 4, Sec. 30, T. 58, R. 29 W., where 
an arrangement into belts and the usual division of the diabases into massive 
lower portions and amygdaloidal upper portions is distinctly to be mace out. 
1 See Foster and Whitney, op. cit., pp. 64, 65. 
