Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1936-01-11

although 1t may be in min
ute specks called polymers.
When oil and water are both
present in a sand, the oil
floats to the top, so where
the wafer travels through
sands that are bent upward
into an arch. tile minute
specks OF oil GO her, drop by
drop, over millions and mill
lions OF years, into an ever
growing pool while the heav-
Ter water. halted in its cir
Otdation by the trap sur
rounds the pool. holding the
oil in the high"
The FREDERICKSBURG supply
Of water from rains and SHOWS
melting on upturned strata in
the mountains keeps washing
more oil into the sands. I'M
til the arch is filled to over
flow.
In the early days Of the
oil industry, oil seeps led 70
the location of all tests for
oil. But presently an obser-
wing scientist noted that all
of the pools were being found
on the top Of folds in the
ear.h's surface. He found that
the region where oil was
found was folded into a series
OF waves SUI cession OF
ridges and hollows. He called
the ridges or up-folds ''anti-
clines, I" and the troughs be-
tween "synclines."
We find tremendous oil
seeps in the Rocky Noun aims
as proof that this is the
source Of the oil. The OIL dis
titled from the shales by the
heat and pressure fills he
sandstones which underly the
plains OF Montana.
The pressure which up
warped the Rocky Mountains
was so great that It pushed
gigantic mountains across the
prairies for so miles. forming
the great Lewis overthrust.
Think what this terrific pres
sure must have done to the
forma ions along the east face
of the mountains:
The result is a series OF
waves or folds in the earth's
surface. The soft shales and
sandstones bent readily. The
lines and some OF the harder
sandstones bent and broke
faulted. Sometimes these
breaks were so terrific that
they broke through to the
surface OF the earth
In figure S Is shown the re-
BuIe oe &his pressure. The COM
pstent formation. In this case
the Madison limestone. at
depth, Is perhaps folded more
sharpiey than are the sub
competent forma ions such as
the Kootenai nd Colorado
shales.
IN figure 9 are shown the
results of the terrific pressure
near the mountains. where
ron inued pressure may make
a simple anticline overturn
and resolve itself into a
thrust fault, giving prob
lens which even a geologist
cannot solve, without drill
ing. The area close to the
Rocky Mountains doubtless
contains some great oil pools
but It is a problem 20 find
them in the complex folding:
a much greater problem than,
as an example, out on the
gentle but simple folds OF
DO Sweetgrass Arch. 40l or so
miles east Of the face OF the
mountains.
Figure 7 shows a thrust
fault, where the competent
bed Is broken in Two and APP
pears on the surface of the
ground. Such a fault Is
found at Sand 'Coulee, south
OF Great Falls. where the
Madison Iime-huried from
1900 TO 1000 feet at Kelvin
lis brought to the surface.
Were it not for faulting,
II would be relatively easy
to find oil traps, but scores
of wells drilled on what an
peared to be perfect folds
have failed to find oil because
faulting has cut off the MI
grafton of oil.
On the other hand, faulting
e perhaps the most important
factor in the accumulation OF
oil. for faults may be deep
seated, starting in the old
est formations and extending