Wisconsin herald. [volume] (Lancaster, Wis.) 1846-1849, 1847-05-08
The valley of the great grandfather Of
Lake Superior.

SlcNaiuu Oh tne strata aiong tniS Tiukes
we have no means of knowing. The
magn, 5ian limestone or lead rock in
which this ridge is now most apparent,
seems TO lie ia large basin, extending
from Blue Mounds on the north about
eighty miles to the south line of 10
Dayiess county, Illinois, and an aver
age width Of about sixty miles. This
rock is intensely hard--the upper sur
face being composed of hornstone--
and the body of the rock being filed
with ebert and nodules of flint. 0nly
a small portion of even this rock has
been able to resist the denuding force
to which the whole country has been
subjected, and few scattered mounds
alone remain as landmarks OF earth's
olden boundary. or the underlying
strata, the blue limestone out-crops
near the Wisconsin, river, and then fol-
lows a series of sandstones and shales
with mixture of arenacious lime
stone, extending north probably to the
region Of trap rocks and copper mines
on the shore Of the great lake.
We have been thus particular in de-
scribing the present position Of the
surface, for the purpose of saying a
few words intelligbly about the dilu-
vial currents which at some period
appear TO have swept over it. That,
the whole country was formerly sunk
beneath an ocean, is truth which no
geologist will deny. The multitude of
fossil she'll fish found in the limestone
are alone sufficient to prove this. If
then, when thus sunk, strong oceanic
current similar to the Gulf stream, had
for long period Of time set south
ward, it would probably account for
most Of the phenomena at present OBJ
servable. II such range of high
land as we have supposed, existed TO
the north Of US, the effect of such a
current would be to tear it away and
spread it over the country to the south /;
that such force has levelled down
such ridge we cannot doubt. The
sandsiones being easiest broken and
carried oil have been most affected
and long sandy region covered to
some extent with pine, now marks the
outlines. Jagged points of the same
rock are met with over the whole re-
gion, giving particularly wild and
dcsolate appearance to the landscape.
The same current swept through the
lead region, tearing up the rock and
carrying vast masses Of it away, to an
average depth of at least six hundred
feet over the whole surface IT the
mounds alone remaining. The hard
ness Of the rock withstood 10 Ger.
tain extent, the force of the flood.
That such force has swept the
lead region is evident from the follow
ing considerations. The strata in the
mounds are horizontal, and can be
traced without MISUNDERSTANDING
with different varieties Of the same
rock. If we take several coin, laying
a larger one, as a dollar, forinstance, at
the bottom, and others of smaller di-
mansions, decreasing TO half dime at
the top, it will very wei! represent their
formation They could not have been
thus deposited without the contiguous
and intermediate country had been
filled up, for we find the same kind of
strata at the same elevation on all the
mounds. Neither have they been ele-
waited, for the strata at the base and
over the region is unbent. Hence the
certainty that they were left in the
general denudation. This conclusion
is strengthened by the strie or scratch
es on the surface OF the remaining
rock, caused by large masses or bould
crs having been forced across them
Also from the finding of float mineral,
which was originally deposited in lodes,
but the matrix Of the veins having
been torn away, the mineral was bro
ken in pieces and spread over the sur
face.
Another evidence Of this great cur
rent can be seen all around US. The
elevation on which Madison stands and
the hills around are all composed of
ift;'-that is, sand, pebbles, and
boulders. On the shores Of the lakes.
a dozen varieties Of granite blocks
can be almost any where seen. These
rocks are surely foreigners-although
their residence here has been long
enough TO satisfy the most 5igoted ma
live'-even If native rocks act as stu
pidly as some native citizens. No rocks
Of the kind exist nearer than the shore
Of Lake Sdperior, and hence they