30 Messrs. Foster and Whitney on the 
stone. Even in that state, according to Hall, groups which, at 
one extremity, are of great importance, and well characterized by 
fossils, cannot be identified at the other. 
The great mass of the materials which form the sandstones of 
this region appears to have been derived from the northwest, 
since the, beds there attain a much greater thickness, and are 
composed of coarser sediments. They thin out as we trace them 
south and east, and are charged with fewer pebbles. On the 
Atlantic slope, according to the Messieurs Rogers, the sandstones 
Qs 
i*) 
9 
=) 
re) 
© 
a 
— 
® 
= 
-_ 
ts 
® 
= 
oP 
ts 
© 
pom 
poe 
= 
PS) 
7 
al 
i) 
e 
ao 
© 
w 
=) 
S 
or 
=i 
© 
© 
tp 
or 
2 
a 
jon) 
he - ? . . - 
northwest, while the intervening space which formed the ocean 
bed, is occupied by the paleeozoic series. 
Sandstones of the Northern Shore. — On the northern shore of 
with conglomerate layers, which become interstratified with trap 
layers, and an enormous amount of a volcanic overflow crowns 
the formation. 
* * - 2 * * 
Sandstone of the Southern Shore.—Between Keweenaw Point 
and Isle Royale, there is, as we have before remarked, an immense 
curvature of the strata, probably reaching five hundred feet below 
the ocean level. A narrow belt of conglomerate and sandstone 
lines nearly the whole southern coast, from the head of Keweenaw 
Point to the Montreal river, beyond which, the latter, no longet — 
in vertical cliffs, which afford many scenes of great beauty. ih 
age 
em 
ledges, or reefs, along the lake shore, but, at a few points, it rises 
