INNER TRAP BELT OF THE PORCUPINES. 215 
with few or many porphyritic feldspars. The thin sections show this rock in 
some cases as a typical ashbed-diabase, with a few porphyritic orthoclases, 
and in others as a true diabase-porphyrite. The latter presents very 
numerous porphyritic orthoclases in an excessively fine base, in which 
there are portions which polarize only very feebly or not at all, and in 
which minute tabular plagioclases with rare augite, magnetite and ferrite 
particles are the only recognizable ingredients. Some of the beds are of 
the ordinary type of fine-grained diabase, and the amygdaloids present no 
unusual characters. The rocks of this belt can be seen to best advantage 
on the upper Carp River, in sections 19 and 30, T. 51, R. 42 W.; on the road 
from Union mine to Carp Lake, in Sec. 24, T. 51, R. 43. W.; along the course 
of the stream south from the same road in the NE. 4, Sec. 23, T. 51, R. 
43 W.; in the NW. 4 of the same section along the larger stream which 
runs into Carp Lake near its southeast corner; and on the Little Carp 
River in sections 17 and 20, T. 50, R. 44 W. 
On the upper Carp the junction with the overlying conglomerate is 
seen at 450 paces north and 
1,630 west of the southeast 
corner of Sec. 19, T. 51, R. 
43 W., where the strike is 
northwest, and the dip north- 
east 25°. Hence up stream 
to the junction with the in- 
cluded conglomerate at 282 
paces north and 1,630 west 
of the same corner the ex- 
posures are nearly continu- 
ous and show much of the 
fine-grained reddish meia- 
7 7ATr 3 400 paces lo 
phyr, besides several bands -_— 34%. 
of amygdaloid and diabase of 
Fic. 4.—Map of exposures on upper Carp River, Porcupine 
Mountains. One inch=90 paces. 
the ordinary types. Thethick- 
ness between the two conglomerates is about 200 feet. The upward course 
of the stream follows the junction with the lower conglomerate to a point 
