The Harrison times., 1901-02-09

to perform function in some other
manner; nothing is lost throughout
the realm of nature. This mode of
reasoning does not apply only to the
crystalline cap rock, for we find the
two mineral horizons, more especial
ly the Black Lead, sealed in at top
and bottom by thin strata of imper-
yious states or shales. We're it fact
that water solutions rather than
gases are entitled to first place as a
basis for reasoning regarding the
origin of ores, would it not have
been wiser and better for every ave-
nue. to haye been left open for waters
to descend? We find not only that
prevention of gas from escaping up
ward was provided against, but al
so that at the bottom of the White
Lead an impervious floor ofthe same
shaly material was placed which, to-
gether with the partially mineralized
and cemented upper portion of the
Basal Sandstone, through meager
seepage of sulphide solutions from
above, prevent the further escape of
these solutions.
In the vicinity of Mine La Motto
the thickness of this cap rock is ap-
proximately 200 feet and at the St.
Louis Insane Asylum according to
the drill record it is almost 300 feet
thick. This -rcck t2-z2alls-=----1;+ss.---' IL
the ones below, except the Basal
Sandstone. are seldom exposed at
the surface. Next, ascending, is a
group of measures named by Gala
her, respectively, the Lower Green
shales, Lower Mud Rock, Upper
Green Shales, and Upper Mud Rock.
They are each about 20 feet thick,
except the Upper Mud Rock which
contains some good building stone
anu ulIS IL OAI fO " OO INCl III
ness. The principal purpose of these
horizons appears to have been that
OF still greater protection to the
great mineral garner beneath.
The topmost member of the Cam
brian has been named the Silicious
Cap Rock. 1t is claimed to be the
most silicious limestone in the whole
Cambrian Division, and to reach a
thickness of $50 to 200 feet. About
its full development is to be seen
around the head OF Middle Fork of
Black river, in Iron county, Missouri.
The exact boundaries of areas in
Missouri that have for their surface
rocks members of the Cambrian pc
riod have never been determined,
neither has this geological divisich
been differentiated until just recestly
by the late Prof. Gallaher who hd q
noble work in Laying rne foundation
for successors to build upon and to
throw additional light upon the geol-
opy of his state that could never have
been obtained in any other manner.
| Without more explicit explanations
it has been almost impossible to dis
tingrish and de6re any one particu-
lar member O. horizon of either the
Cambriap or Silurian periods, except
through guidance of the sandstones,
and these have such a lithologicall
resemblance to each other as to, on
/ some occasions, create a doubt.
True it is, however, that conditions
are liable to great changes in this.
respect, and much of a geological
scale that may be prepared should be
considered with due allowance.
Heretofore, in describing ore bod
les outside of the disseminated leae,
rocks of the Cambrian, they hy< 4
been referred to as occurirD
Magnetism limcstone |
posed Lower Silt
must not be suppose
per limestones are b. a
There can be no dOub,
is more mineral, by fa
series of the Silurian ar
iferous periods that over,
brian than there is in
White horizons of tn:
the former, it is cocited.
| Excl