Dodgeville chronicle. [volume] (Dodgeville, Wis.) 1862-current, 1871-12-29
MINING DEPARTMENT T.

river, and near the fourth principal mer.
idian, there is a good exposure of rock
along all the streams Whether the low
er strata is brought up here TO a higher
position by the same causes that brought
it rp to a higher position in the lead dis
trict, and to the north of it, is hard to saw
from the fact that here, on the south >ho .
of Lake Superior. re are on a well defined
east and west axis of elevation, aud Just at
its junction with this North and south axi
A. all events We have a good exposure Of
the aZoic formations here, and this was
what was specially anxious to find.
From what | could see of the rocks from
The Penokee range To the lake, they were
alternate beds of slate, trap. syonite, cong
lomerate and sandstone. The sandstone
is no doubt the equivalent OF the pot>dam
sand stone. out il contains here a large
amount of foreign material. The trap.
varies very much 10 its Character, and even
in composition. In some places it is a
fine grained, hard gray rock. which looks
rather forbiddins for mining purposes
In other places, however, it passes into
a beautiful brown amy zdaioid trap, filled
with patches OF chlorte, and lunches OF
calcareous spar, and looks as though it
was prepared By nature especia lily for ore
deposits. In the fine seems of spar, that
traverse this rock in all directiehs, may b.
often seen strings, Gas the miners would
call it), of native copper. Over the bed
of streams, and up their lodges along their
sides, these seams are marked with gree n
tinge of the carbonate of copper, which.
when, removed, shows the native copper
sparkling like gold. In digging after some
of those strings of Upper, especially those
found in views of laumorite. felt stirring
within .mellthose feverish feeling of TX
element which miners always feel, when
following a small string OF ore near to the
deposit Of which it is branch. These,
however, are but small portion of the
mineral Indications that will stir feveri>h
feelings of excitement by and by, when
this part of our State is opened up to cifl.
llZatlon. s"t ## l-..t>'2s
The course of these different beds OF
rock is usually little to the nor tn of east
and south Of west, hut Occasionally bend.
ing around to nearly north and south
They are tilted up at very high ahge, n
some places as much as so degrees, and
pitching to the north, or generally TO the
f.
northwest.
Bnt few places where tie azoic rocks
are exposed as the surfac: rock, do W
find stronger evidences of mechanical dis
turbance, and long continued exposure
to heat, than here. The mechanical forces
however, by which these strata have been
brought up to such an angle, do not seem
to have acted through great violence, but
to have acted through periods Of time.
The rock are not FEATURED, as they are in
many places, and the system of dyke are
mostely, Gas far as what came under my
observation Drumming with strata, and be
tween the different beds, crossed by small
er veins cutting the strata at right angeles
At one plaee on Bad river VIII re there
are two fails, each fifty feet or more there
beautiful exp 'snre Of trap, conglomer-
a tie and other members of thesnzoic forma
ion. Those different beds are almost
north and south. Whrreal could get d
good sight with the compass, the hearing
WAS about north, ten degrees. Betwe, q
the trap here (Which is beautiful amyZa
loid and the conglomerate) there is what
the Cornish miner would call a great
cross. course. 1t is from 80 to 40 feet
wide, and the order of its formation and
filling is as follows. The trap presents .
| regular smooth wall, as. fne specimen
of slickened wall rock as we .usnslly fnll
in a true tiSsur4 vein. On this wall is
very fine grain fiucan, from 4 to 6 inches
wide, having all the characters of. fucan.
peculiar to true mineral veins. Next To
this fucan is # blue and reddish clay,
passing into a soft clay slate, with bun
ches Of Gale shar, !aumonite, prrhnite,
and other minerals Of this character
The chemical arrangement Of this ma er.
al is beautiful. I..gl. s,a 1.fTg i. =
This was evidently onre a, assure on q
large scale, produced by the mechani al
forces which lifted these beds Of TO k
from their once haliz,ntaI, to their pre-.
ent nearly verticle position. The filling
of this assure, however, has ben brought
about by the action of chemical fareeS on
the material brought into it in solution
The material itself, the conditionin which
it is found, and it's arrangement in the ifs
sure, forbids even the supposition of any
other process. sa @a
This is one of the places where nature
permits Us to look upon the results of me-
chaniea' and chemical forces in their nor
mai lnuluoH. WHERE sue draws D2ck,
as it were. the covering that hides them
from our view in the lead district and1in-
vites Us to examine the forces and condi-
tons that resemble (if not the same) those
that underlie the phen mena there eaiss
In mining language. a cross course is
not a mineral vein, although have known
them to be productive where crossed by
mineral veins They are very mueA wild
der, are seldom, if ever known5to give out
in depth. and extend in length almost in
definitely. They seem to bear a close re-
lation to the axis of elevation, and always
runs parallel TO Its longest course, which
is, most cases north and sonth a.
Mineral veins which are found some
times on one side and some times on the
other, and some times crossing them, are
always at right angles to them, hence
their nam Ceres courses. In the mining
districts Cornwall there are instance where
as several of those districts are knownto ex
list on the line of the same cross course
a system of cross course. They forming
not only the basis of the mining district
but the connection link between them. av
Mazomanie, Dec. % l87l,a ri vT.1