Grant County herald. [volume] (Lancaster, Wis.) 1850-1968, 1854-06-05
From the .. 8. Mining Journal, en-. W
Geology Off1Re Lead Mines of wis
COmsin.


cOnsin.
At the recent assembly of the A
merican Scientific Association, Professor
Daniels read valuable paper upon the
Geology of the Lead Mines of Wiscon-
sin. He said:
unfortunately, he had lost his bag
gage while coming East, and with it a
large number of specimens and charts
with which he had designed to illustrate
his paper. He had, however, drawings
of all the fossils found in that region and
sections sufficient to make it perfectly
plain. The country particularly noted,
embraced the several counties in the
southwestern portion Of the State. In
this region there is an entire absence of
"drift." Though in other portions of
the State they abound, south of the Wis
conSin river there is very seldom to be
found either boulder, gravel-stone or
clay. The land lies some 500 or 600
feet above the level of Lake Michigan.
A few points rise as high as 1900 feet
above that level. The dip of the strata
is about 10 feet to the mile. The
mounds are isolated points Gaping the
table-lands. The surveys for railroads
through different parts afforded the ge-
ologist many facilities for examining the
underlying strata, and they developed
remarkable regularity throughout. At
the Mississippi, in the southwest corner
Of the State, the blue (Trenton) lime
stone appears; the next layer above is
a sandstone, the next q limestone, the
next middle sandstone, the next, the
blue (Trenton) limestone, aud above all,
The lead-bearing surface-rock, often 800
feet thick, is gray limestone. In this
are most Of the fossils found, and there
generally the veins of galena occur.
"IEe veins are vertical, so long as
they continue in the rock. At certain
points The veins occupy large assures in
the rock. The galena is in large crys-
tails, clinging to the tops or sides, and per-
iectly pure,-never at the bottom, ex-
cept as they are broken off and mingled
with pieces of broken rock. But when
we PASS deeper into the Trenton lime
stone, the veins are ofLoner horizontal,
spread in flat, thin sheets. Here the
lead is combined with the oxides and
sulphatcs OF iron and zinc, -''blacki jack"
and "dry bones," the miuers call it,
Heretofore the popular belief was that
the lead failed on striking this blue lime
stone, but at several points he found that
without being aware of it, the miners
had worked past even the limestone in
to the sandstone, and found rich veins
even there. These lateral veins of the
blue Frenton) limestone lie parallel to
each other; they extend great dis
tance, and have been worked for mile.
Prof, Daniels inclined TO think that the
deeper veins VIII be found not inferior to
those nearer the surface. He found oc-
caSional veins Of copper, but they were
entirely independent Of the lead veins.
The lead veins are il groups, and their
lateral veins seem to connect the larger
vertical ones of the same group"
Prof. Hall said that in 1850 this Ga
lena limestone was first identified with
the Lower Silurian rocks, and he tho't
the belts spoken of were all of the same
age. This region had never suffered
from great pressure below, and he tho't
that the veins of lead had not been in
jected into the assures from below, but
must have flowed in from above, while
in watery solution. The reason why
the veins were horizontal in the blue
(Irenton) limestone, was because the
assures in the rock were lateral-not
that the veins had been pressed togeth
or and thrown up latterly after they
were filled. The shale above the lead
bearing rock he supposed TO b. of the
Hudson river group.
\ gentleman present said that in the
Missouri Lead Mines the mineral found
in caves, which, being excavated, form
ed perfect labyrinths that they some
times worked it over five, ten or TWEEN
ty acres, making labyrinth SO difficult
TO thread that within that little space
men were sometimes lost, wandering for
hours.
Professor r. E. Rogers said that in
discussing the veXed question of the orr
cir of mineral deposits, we must not de-
ny that there has been pressure from
below, simply because the earth's sur
lace seems unbroken ana regular. An
earthquake that causes no disturbance of
the surface, fills the air with sulphurous
vapor, and doubtless great pressure
might force metals in sublimated state
through many strata to be crystalized in
caves and assures.
DIR. ]. Lawrence Smith suggested that
it might be simply process Of segre-
cation taking place, not while the rocks
were in liquid, but in plastic stafe,-
like seeking like, urged by powerful af-
iinities, and on uniting, forming in crys-
tails and otherwise.
Professor Hall was understood to give
it as his opinion that the richest veins
would be found only in the gray lime.
stone, where the mines have been wor-
ked generally, land that they would grow
thinner and poorer as they passed lower
"a practical point of great importance
ES@We are told that the heavy rains
last week washed away several thou
sand yards of earth from the track of the
Mineral Point Railroad, OH a portion o
section seven that was not complete
The bro,iy bouave~ will Soou he re