54 Editorial Com'ment. 
Keweenaw rocks, and of this presumed equivalence there are 
good reasons for entertaining much doubt. 
lyie Credner view conceives of the eastern sandstones, the 
traps and conglomerates of Keweenaw point, and the sand- 
stones on the west side of the point, as constituting one con- 
formable series of strata, the sandstones on the east passing 
below the principal mass of the trappean rocks, and those on the 
west lying conformably above them. In this view the sandstones 
are not of the same age, and the eastern sandstone is the older. 
This view is substantially that which is held by Dr. M. E. 
Wadsworth. 
This requires in the opinion of Messrs. Irving and Cham- 
berlin, an incredibly great amount of denudation to account for 
the non-extension of the trappean beds toward the south and 
east of Keweenaw point. They show, by a diagram drawn to a 
scale, that when these beds were intact, on this hypothesis, they 
must have had a thickness on Keweenaw point, in addition to 
their present perpendicular altitude, of about four miles. They 
may have stopped there in an imagined perpendicular cliff, or 
they may have been extended conformably eastward over the 
lower strata of the eastern sandstone. The latter alternative is 
accepted by the authors as the only reasonable one, and then 
thv-y find insuperable difficulties in the way of the Credner view. 
These consist in the entire absence of these strata toward the 
southeastward where this alternative would require them, and 
the existence of the " singularly abrupt linear, often cliffy, south- 
ern limit of the trappean series." Another difhculty is the fact 
that the eastern sandstone graduates upward, a few miles away 
from Keweenaw point, not into the Keweenaw locks, but into 
the Calciferous sandstone, and that the Trenton limestone, even, 
is seen probably in its true stratigraphic position (above the Cal- 
ciferous) in the same region; "it is a heavy strain on our cred- 
dulity to ask us to place the great Keweenaw series in this inter- 
val." The evidence which Mr. Wadsworth has presented to 
show the correctness of this view consists of four postulates, 
(i) The eastern sandstone passes conformably beneath the 
trappean series, (2) as it approaches the Keweenaw range it is 
interstatified with rocks identical with those that make the bulk 
of that range, (3) it shows an induration due to heat from trap 
