360 The American Geologist. June, 1895 
graphically and petrographically these are essentially equiv- 
alent to the series which have already been mentioned as 
Grenville and Hastings, but less crystalline. The conglome- 
ratic non-conformity upon the lower Laurentian, the rather 
slight crystallization, the association with characteristic basic 
and acid eruptives, the superjacent non-conformable Upper 
Cambrian, are points which show their agreement on the one 
hand with the Norian of the Ottawa valley and of the Adi- 
rondacks, and on the other with that of the west side of lake 
Superior. There is no possible other inference without a vio- 
lent traverse of the most natural and manifest conclusion of 
geological judgment. The details of the comparison need not 
be entered upon here. 
Reference may further be made to various places in the 
northern part of Canada, where, in the opinion of Dr. G. M. 
Dawson, the Lower Cambrian eruptives exist. The descrip- 
tions of Sir John Richardson are quoted by him in his "Notes 
to accompany a geological map of the northern portion of 
Canada east of the Rocky mountains."* These rocks occur 
along the Coppermine river and in the Copper mountains. 
It is further quitf evident tliat in tin; extensive area colonic! as Cam- 
brian on tli(! Arctic coast, in tlie vicinity of tlie Coppermine river, the 
rocks are analogous in character to those of the Keweenaw or Animiivie 
of the Lal<e Superior region, and probably represent both ffroupsof that 
great copper-bearing series. The mere occurrence of native copper in 
considerable quantities on the Coppermine, in association with prehnite 
and other minerals resembling those which accompany it on lake Su- 
perior, gives ii J) rima facie TprohahiUty to this correlation, which is borne 
oiU. bj' a more careful study of Sir J. Richardson's accurate notes, and 
M^as recognized by Richardson himself, who had examined both re- 
gions. (P. 8R.) 
To this age also he refers rocks upon the Great Slave lake, 
and on the route from Great Slave lake to Great Fish river, 
also the great volcanic series of Dr. R. Bell, the Manitounock 
group, of the east coast of Hudson bay, and the red sandstones 
of his '•'intermediate group." 
Throughout tlie whole of the vast northern part of the continent 
this cluiracteristic Cambrian formation, composed largely of volcanic 
rocks, apparently occupies the same unconformable position with re- 
gard to the underlying Laurentian and Huronian systems. Its present 
remnants serve to indicate the position of some of the earliest geologi- 
cal basins, which, from the attitude of the rocks, appear to have under- 
*Geol. Sur. Can., vol. ii. New Series, Rep. R, 1887! 
