54 R. Irving—Copper-bearing Rocks of Lake Superior. 
The only difficulty in the way of these conclusions lies in the re- 
markable phenomena presented at those points in Douglas 
County where the horizontal sandstones are found joinin 
the traps. The first explanation that offers itself is naturally 
that these remarkable. disturbances were caused by the protru- 
sion of the trappean beds through the already Foemed: sand- 
stones. In answer to this it may be said, (1) that it is exceed- 
ingly doubtful whether the protrusion of molten matter through 
horizontal layersof sandstone would produce any such effect,— 
at least I cannot conceive how it could ; (2) that this remarkable 
disturbance is unaccompanied by any hardening of the rock, ap- 
pearance of baking, or other evidence of great heat; (3) that if 
these trappean beds are of the same Copper-bearing Series as 
those in Ashland County, then the proof of unconformability 
there found is conclusive of the greater age of the traps as com- 
with the horizontal sandstones ; and (4) that hence we must 
nd some other explanation of these phenomena. e only 
one that appears at all acceptable to me is that the traps, being 
deep-seated and non-continuous with the comparatively 
superficial sandstones, would, if impelled to move by an 
force, tend to move, to some extent, independently of the sand- 
stones, and would, by an exceedingly slight motion northward 
against the latter, produce precisely the effect observed. 
IL. Westward continuation of the Lake Superior Synclinal. 
“Take Superior,” issued in 1850, I find a dotted line with a 
query made along the center of the peninsula of La Pointe, or 
Bayfield, indicating that possibly it has a trappean core and 
owes its projection into the lake to that core. I think there 
is reason to believe that this is true, and that the core of that 
peninsula, with the Douglas County traps, forms the westward 
continuation of the Isle Royale or northerly side of the syn- 
clinal just alluded to; that hence this synclinal trough, in its 
westward extension, does not hold the lake, but passes entirely 
on to its southerly shore, and that it is not improbable that the 
line of southward-dipping sandstones, in Ashland County, 
marks the southerly edge of the northern side of this synclinal. 
However, inasmuch as there is no direct proof that the 
trough between Keweenaw Point and Isle Royale is a simple 
synclinal without subordinate folds, these southward-dippmg 
sandstones may represent one of these subordinate bends 
rather than the northerly edge of the trough, and this seems 
the most likely supposition. — 
