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


waters OF the granite hills and the
lead-carrying waters flowing back
and forth through the la Motto
sandstone, and issuing as springs,
came into contact with the arms of
the Pennsylvanian sea, chemical
changes took place which brought
about the lead deposits being worked
to-day. The heavier solutions of
lead had cOngregated in the La
Motto sandstone and being forced by
hydrostatic pressure into the lower
portions of the Bonne Terre lime
stone, which lies just above the
sandstone, the lead was deposited
Lead Being Deposited Now.
This process is continuing today.
The waters from the la Motto sand
stone show the presence of lead In
almost the same percentages in
which it is present in the GRANTEES
and porphyries. Wherever the con
ditions are right, and particularly
whore the limestone contains or
ganic matter, rs is shown by it's
darker character, the lead held in
the waters of the sandstone is pre-
cipitated as very small PARTICLES Of
galena, and thus the disseminated
deposits are formed.
In this process, continued through
n period of II 900, 900 years, the chief
deposits taking place probably about
$4,000, 600 years ago, we see many
causes combining, and it probably
was because of these numerous and
peculiar combinations of causes that
there was created in the Flat River
district practically the only disscm-
mated lead ore body in the world.
Similar geological circumstance
did not exist at other points on the
carth's surface.
summed up, it may be said that
three or four oceans, the granite
hills known as the St. Francois
Mountains, and the coal fields of
Southern Illinois were the deter
mining factors In the disseminated
deposits Of the Flat River district.
The Illinois coal fields furnished n
greater part of the organic matter
which was necessary to the precipi-
tation and deposit of the lead from
the waters holding it in solution.
Hard Problem for biologists.
The origin of the disseminated
lead deposits has long been "A prob
lem with biologists. Gradually, all
of them have practically accepted
the theory of Arthur Winslow,
which has been expanded to some
extent above by the addition Of fac
tors discovered by DR.. Buckley. In
n discussion of the Flat River dis
trict, Mr.. Winslow has this to say
"Onc of the principal determining
causes, (of the disseminated de-
posits) we think, was the original
open structure or texture of part of
the rock. This is often observable
now, and especially characterizes
ore-bearing strata. Second, n prev
alence of organic matter in certain
strata or along certain horizons, as
indicated by darker color now
often seen, had doubtless influence.
Further, the various shalc beds prob
ably limited and guided the solu-
tons.
Numerous vertical crevces fur
nished channels for the flow of the
solutions. The sheets of galena
frequently found in these crevices
prove that the solutions followed
them. These were sufficient to sup
ply the ore of higher-lying dissem-
mated bodies. The contraction and
disappearance of the crevices with
depth, make them inadequate for the
deep deposits such as prevail along
Flat River.
"For these ores we are inclined to
refer to the underlying sandstone,
which is In close proximity, as the
solution carrier. This is saturated
with water, much of which flows di-
rectly from the decomposing crys-
talline (granite) rocks. The sand.
stone itself contains particles and
fragments Of these rocks, which
must hold more or less of the metals.
"A downward flow of water to-
ward Flat River and Bonnie Terre is
induced by reason of the slope of
the Archean (granite) floor, and al !
so by the Pennington anticline to
the east. The water is thus under
pressure sufficient for II to rise up !