The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1920-07-29
PROSPECTING FOR OIL
FACTS AND FICTION
SOME PRACTICAL INFORMATION
FROM U. S. GEOLOGICAL SUR
VEY-olL WITCHES.

There are only a few kinds of true
surface indications of petroleum, anC
most of them are easily recognized. In
regions where oil has not proved &c
exist either oil, gas, or some blum
nous substance that once was oil is
the only reliable indication of its
presence. Oil may seep from a por-
Gus bed or ooze from joints in the
rocks, or it may issue with water at
some small spring or may form a
film on pools. in swamps or meadows,
or in water wells AT most such seep-
ages the oil escapes in but small guam
titles yet the rainbow hued film il
spreads on water and its odor are al
most certain to attract attention.
These and other hints for the oil
prospector are suggested by X. c.
Head, an oil geologist of the United
States geological survey.
In some places oil fills the pores or
appears at the surface, but it does
not flow II may appear as tarry
patches on the face of the rock or it
may emit an odor. particularly on hot
days. The weathered surfaces of the
rock in many such Oil soaked beds
however do not emit an odor nor do
they show any indications of oil, al
though when the rock is broken its
fresh surfaces may fairly reek of pc
troleum. Some such rocks give no
odor of oil even when freshly broken,
but when they are subjected to simple
chemical tests they yield traces of oil,
bitumen. or parafiin.
In the California oil districts beds
of burned or clinkered shale are al
most as significant of the presence of
petroleum as Oil-saturated beds. At
some places the shale was saturated
with oil that seeped from underlying
beds and was then in some way ig-
nited and baked into a brck-red to
bright cherry-red mass ranging in
hardness from that of soft building
brick to that of almost CLASSY Stag
The California oil region is the only
known place in the United States
where such burned shales indicate the
probable occurrence of oil, although
shales have been similarly baked in
other regions by burning coal beds that
lie near the surface.
Characteristic Surface Showings
In some places large quantities of
oil have escaped to the surface and
formed deposits of asphalt or other
bituminous substances. Such deposits
indicate that oil once existed in the
region and that the region is worthy
of careful study. but they are not
certain indication of the presence of
petroleum, for all the petroleum may
have escaped to the surface. or it may
have been altered to some bituminous
substance from which oil can not be
extracted.
In some regions salt water springs
sulphur water springs, gypsum, rock
salt and sulphur are associated with
oil On the gulf coast of Texas and
Louisiana gypsum or rock salt on the
surface or in water wells may indi-
cate the presence of oil as the oil
fields of that region are commonly as
ISOLATED with salt domes" that con-
tain great masses of salt and gypsum /
These minerals, however, occur also
has been found and where it can not |
possibly exist
False Signs and Oil indications"
Many things are frequently referred /
20 as indications of oil which have no |
connection whatever with it. Prob
ably the most common of these is the
rainbow colored film produced on wa
ter by iron oxide or manganese oxide.
Or by decaying animal or vegetable
matter. This film can easily be dis
from the film produced by /,
oil. for il has no smell of petroleum
and il is brittle, whereas an oil film
is tough An oil film when stirred VIII
become streaked with colored bands n
that double and twist about but do
not break apart, and any openings
that are made in it have smooth
edges which are likely to draw to-
gether Rainbow" films that do not ,
Indicate oil will break into separate
patches when stirred, and the patches {
are not likely to join again into one .
smooth sheet These little patches .
nave edges with sharp corners and s
many of them are divided by narrow q
racks that show no tendency to h
ilose. II
1t is often said that a country t
looks like oi''-that is. the surface a
sives the speaker the impression that "
I must be underlain by oil This re- a
mark means only that the country
ooks like some other oil producing t.
egion which the speaker has visited. o
'he surface appearance of a region, I,
However. means absolutely nothing as f
the presence of oil for oil r.
nay occur under a surface of any 2
ind. from the orange groves of Cal n
rornia to the alllali plains of Wyom- il
ng; from the ice-encircled hills of d
.laska to the sun-blistered table q
lnds of Utah And. similarly in many is
egions where the surface is of ex- ii
city the same type as that in certain al
il fields there is not a drop of oil in
ome men declare that a guide 20 oil tc
nay be found in the egetation-the al
rees. bushes. grasses. and flowers. ok