Editorial Comment. 53 
eastern sandstone was laid down. It also supjDOses that the Ke- 
weenaw series extends unconforniably continuously beneath the 
eastern sandstone to the "south range," the entire trough in 
which this sandstone lies having been produced by erosion. To 
this view the authors object because it necessitates an inconceiv- 
ably great thickness for the Keweenaw series, and an enormous- 
ly great erosion prior to the deposition of the sandstone. With 
modifications, however, this view is adopted by the authors. 
They remove both of the difficulties by supposing the south face 
of the trap range to have been in the first place the result of 
faulting. 
T'he Rommgcr victv. Accoixling to Dr. C. Rominger the 
eastern sandstone was once extended conformably over Kewee- 
naw point, and the sandstones that now are seen at the mouth of 
the Portage canal near the lake shore, while belonging to the cop- 
per-bearing series, approach the eastern sandstone so closely in 
character that they may be considered as the lower portions of 
that formation. According to this view the Keweenaw rocks 
are older than the eastern sandstones, but on the western slope, 
and perhaps at other places, pass upwaixlly into the eastern sand- 
stone conformably; while on the eastern side, owing to the pro- 
duction of a fault during the accumulation of the sediments of 
the eastern sandstone, running along the east side of the trap 
range, the later sediments of this sandstone are locally unconform- 
able on the trap rocks. 
In rejecting this view the authors cite specificall}- several 
places where the horizontal sandstones lie unconformably on the 
upturned edges of the Keweenaw series, viz.: in the St. Croix 
region, in the Gogebic region and in the region north of the 
Montreal. Further, they do not admit the similarity between 
the sandstone at the mouth of the Portage canal and the eastern 
sandstone. Still they do not state wherein the unconformabil- 
ities to which they refer differ from that which Dr Rominger 
admits on Kewenaw point, and to which he refers for proof of 
the correctness of his view. The authors also refer loosely to the 
"Potsdam sandstone," and thev confound the beds that lie on 
the trap at vSt. Croix falls with the eastern horizontal sandstone 
which they are discussing. They also assume tliat the trap seen 
at the .St. Croix falls is the equi\'alent of that embraced in the 
