The Farmington times. (Farmington, St. Francois County, Mo.) 1905-1926, 1909-09-16

land surface in the United States.
IL.
Just about tlfty-four million year,
ago, accepting the estimates of tn,
biologists at their face value, St
Francois county first came int
| possession Of the lead which is now
being recovered from the dissemin
ntcd deposits at the rate of approx
matcly 100000 900 yearly.
The igneous rocks, which are still
on hand in the red granite and por.
/ phyry of the st. Francois Noun.
tains, were bubbling and stcwinr
from the lowest depths of the earth
at that time, 54,0OO,OOO years ago.
And somewhere from below came
the lead and the zinc, which to-day
are present in small quantities H.
every spcck Of granite and every
bit of porphyry.
Finally these igncous rocks solid
flied, forming the st. Francois
Mountains, which at that time rose
| 800 or 1000 feet above the rest OF
the country. And these mountains
probably are the oldest in the United
States. At least their peaks are the
oldest land area in the United
States, having escaped the inunda-
tons which afterward swept over
practically all the Western Hemis-
pherc.
In the GRANTEES and porphyrics Of
these mountains there existed ut
that time the lead nov found dis
s"minated in the limestone of the
Flat River district. The granite
probably contained an average of
O.OO2lJ per cent of lead and 0.002l
per cent of zinc, and the rhyolitc,
or porphyry, 0.0Oj02 per cent of lead
and 0.0l70j per cent of zine. These
are the percentages shown by anuly-
scs of these rocks.
Stated briefly, large quantities
of the granite and porphyry were de.
composed and crodcd during the Is
100000 years Of the pre-Cambrian
period, and the lead was held in So
luton in the Cambrian ocean. After
ward, the lead in solution was con-
centrated in cracks and creviccs,
some Of it deposited and again taken
up by other waters which followed
these early oceans.
Lead in the Granite:
According to Buckley, one square
mile Of granite, | 400 feet thick,
would yield $1,000 tons Of lead. Just
how many square miles of granite
were eroded during pre-Cambrian
times the biologists do not know,
but they are very certain that about
one-half the lead obtained from the
granite was carried away from this
immediate district and dissipated in
other oceans, while the other half
remained to be concentrated, depos-
tied, dissolved again, and again
concentrated, deposited and dis
solved until conditions became
right for its final deposition in the
Bonnie Terre limestone, where to-
day 1t still is being deposited by the
underground waters, and the pro-
cess will continue indefinitely.
After the Cambrian ocean had
eroded about two-thirds of the area
Of the St. Francois Mountains and
had practically disappeared, lcav-
ing in the valleys between the gran
lite mountains deposit of sand
which is now recognizable as the
LaMotte sandstone and In which
the drill men "bottom" all drill
holes, and on top of this deposits of
dolomite, or limestone, and shalc,
in the cracks and crevices OF which
were left large quantities of galena,
there were several foundations by
ocean waters, and during all this
long period OF time the lead, held in
solution by the water, was being
concentrated.
1t was during the Pennsylvania
period, when the Pennsylvania
sea, bearing large quantities of or
ganic matter, swept in covering the
greater portion of Southeast Mis-
souri,, that the conditions favorable
to the permanent deposit OF the lead
were established. 1t required the
presence of organic matter to ac-
conplish the precipitation OF the
lead, and 1t is because OF the re-
quirement of such conditions that
the areas of disseminated lead de-
posits are so limited In Southeast
When the lead-burdened ground