SANDSTONES AND DIKES OF AGATE BAY GROUP. 293 
red sandstone layer, or rather conglomerate, the pebbles being wholly of 
amygdaloid. Proceeding down the coast, the next sandstone met with is 
the seam already described in the section given of the succession at Agate 
Bay. This sandstone is much like the one last mentioned, descending in 
the same way far down into the crevices of the underlying rock, and inter- 
mingled curiously with amygdaloid. It is only two or three feet thick. 
Still farther down the coast, on the N. E. 4, Sec. 32, T. 5”, R. 10 E., red 
shaly sandstone was noticed occurring with stratiform laumontitic amygda- 
loid, as represented in 
Fig. 14. The sand- 
stone layer with which 
this must connect was 
not seen here. At the 
projecting point near 
the 8. E. corner of Sec. 
1, 53, R.10-W., thin 
sandstone seams are 
to be seen interleaved Fic. 14.—Sketch of cliff on Minnesota coast, showing penetration of 
fissures of amygdaloid by sandstone. 
with the melaphyr, and 
on the shore of See. 32, T. 54, R. 9 W., two and a half miles above the mouth 
of Gooseberry River, is a remnant of a porphyry-conglomerate—the pebbles 
small, usually less than one-eighth of an inch across, and subangular—with 
abundant calcareous cement. 
A very few narrow dikes, much like those of the Lester River Group, 
were observed cutting the layers of the Agate Bay Group. One of these is 
to be seen on the shore of Sec. 34, T. 51, R. 13. W., two miles below Lester 
River. It corresponds in trend with the bedded rocks which it cuts, but 
lies at right angles to the dip. It is composed of a dense black rock, which 
has not been examined microscopically, is very strongly and closely cross- 
jointed, and is only a foot wide. A very prominent dike, five feet wide, is 
seen in the cliff on the shore of Sec. 15, T. 53, R. 10 W. Fig. 15 shows 
the occurrence of this dike, which is composed of a very fine-grained, black, 
luster-mottled melaphyr, the thin section of which looks much like that 
