272 The Aniencmi (ieohxjint. November, 1895 
erate of the Keweenawan or of the Aniniikie. This conglom- 
erate consists largely of red felsyte pebbles, often as large as 
walnuts, and of white quartz. These can of course be referred 
to the Aniniikie underlying which abounds in red felsytes and 
in taconyte cherts. Bell mentions traces of fossils, and re- 
ports the statements of Indians and others that fossils occur 
abundantly in a limestone farther north, which, however, was 
beyond the range of his instructions. The facts seem to war- 
rant a lithological comparison with the "Eastern sandstone" 
of the south shore. 
Thus, structurally, geographically, stratigraphically and 
lithologically, they seem to be the northern representative of 
the Eastern sandstones. But they are interbedded and cov- 
ered by copious trap sheets, a circumstance which doubtless 
has led to their being included by Logan in the "upper vol- 
canic group" of his "upper copper-bearing series," an assign- 
ment which has been followed by all geologists. 
That these diabases were not cotemporary with the sedi- 
ments with which they are now associated is made evident, 
however, by Dr. A. C. Lawson,* and therein they show an- 
other remarkable divergence from Keweenawan characters. 
He points out that the Logan si/Is of the Aniniikie are also 
the diabase sheets and caps of these sandstones, and date from . 
an intrusion later than the sandstones. He suggests that they 
may be as late as the trap dikes which in Mount Royal (Mon- 
treal) cut through the Trenton limestone. Following are the 
characters which show they were not surface flows of molten 
rock like those of the Keweenawan, but are intrusive sheets 
which penetrated the formation and insinuated themselves 
between the beds after the strata were formed. They are 
thus enumerated by Lawson. He applies these statements to 
the Aiiimikie sills, but as he says the trap sheets of the sand- 
stone are of the same age and are visibly continuous from the 
Aiiimikie to the sandstones, they are applicable to the sand- 
stones, j 
T]iey are not rolcaiiic Jloirs In'cauae: 
1. They are simple geological units, not a series of overlajjping sheets. 
2. They are flat with uniform thickness over areas more than one 
hundred square miles in extent, and where inclined the dip is due es- 
sentially to faulting and tilting. 
*Bulletin VIII, Minnesota Geological Survey. 
tO]). cit., p. 4.5. 
