Great Falls tribune. [volume] (Great Falls, Mont.) 1921-current, 1922-11-26
Government Ge0logisf
Reports on Structure
Near Little Rockies

GLOWING the possibilities of de-
- velopment of several small domes
south of the Little Rockies in
Montana, is the recent government re
port by A. j, Collier and 5. Ii. Cath
cart of the United States geological
survey, based on an examination OF
the area in the summer 1871. Ihe
bulletin has Just been published.
Collier is one of the best known OF
the government biologists who have
made examination in the Montana
fields, his reports and maps of the
kevin-Sunburst' field and the Bow
doin dome being accepted largely by
oil men operating in the two areas.
The area described is about 70 miles
from the railway, either the Great
Northern at Harlem or the Chicago,
Milwaukee & st. Paul at Winifred.
This is the chief factor to be consld-
cred in the development of the area,
according to oil men.
The report of the government geolo-
gistS follows:
South Of the Little Rocky moun
tains in Montana, the beds of rock at
a number Of places have been arched
upward into small domes by the heav-
ing or bullying force exerted by masses
of molten reek (~laccoliths) beneath
the strata. Some Ct these doTe may
contain oil. The chances of finding oil
in them are undoubtedly small, but
nevertheless they may present the
most favorable conditions TO be found
within the general region where they
occur. The following description of
the geology of these domes Is the re-
suit Of a hurried examination during
the summer of 1921.
THE Little Rocky mountains, which
are just north of these domes, form a
prominent landmark, rising about p
900 feet above the surrounding plains.
They are 40 miles south of the Great
Northern railway at Harlem. in Blaine
county. The nearest wells yielding
oil or gas in commercial quantities are
those that supply gas at Havre, 20
miles to the northwest, and those of
the Cat Greek field, 70 miles to the
southeast. Showings of oil and gas
have been reported from nearer To-
c%alities. tf.ts,
Rocks Described
The rocks exposed in and around
the Little Rocky mountains are de-
srribed in the following table:
Glacial Grift-Boulder clay con
tanning granite and limestone boulders
from Hudson bay and Lake Winnipeg,
%shonkinite boulders from Snake Butte,
quartzite and other pebbles from the
F1axville gravel and from the Cypress
Hills of Canada.
"Glaciel silt-Stratified clay depos-
tied in lakes and ponds along the ice
front.
Pleistocene gravel and FIaxville G?
gravel-Thin veneer Of gravel on ter
races sloping away from the Little
Rocky mountains.
Bearpaw shale-1,O0O feet-Dark
gray shaIe of marine origin. Con
tains Faculties. ~ammonites, inoceramus,
and other fossils.
Judith river formation-4m feet
Sandstone, shale and thin beds of coal
deposited in fresh and ~brackish water.
Fossils, dinosaurs and many forms of
and brackish water invertebrates
gas iii Baker anticline.
Clagget shale-600 feet-shale close
y resembling the Bearpaw.
Eagle Sandstone-40 to 100 feet
Light yellow sandstone and gray shale
of marine origin-yields gas at Hayre
and oil and gas in Lake Basin.
Warm Creek shale-775 feet. Mosby
sandstone member 5 feet, 36O feet
Dark blush black shale of marine orr
gin Mosby-9 rather thin calcareous
sandstone containing many p~eriwinkle-
like f~ossilsl dark blue marine shale.
Mosby possibly contains oil.
Mowry shale-50 fpet-Marine shale
appearing on outcrop like broken porce-
lain. Abundant fish scales. Contains
traces of disseminated oil.
Kootenai Formation
Thermopolis shale-430 feet-Dark
blue shale with lenses of sandstone, of
marine origin. Few fossils.
Kootenai formation-700 feet-Yields
o. in the Cat Greek field. The most