Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1937-03-27

such nature that they are unsuitable for
either the formation OF oil or gas or their
retention If formed. being very largely crystal
line or metamorphics
/ Wells and surface data indicate that the
western portion Of the region, as well as the
southern, were subjected to much greater
periods Of submergence than the northeastern
portions, hence stratigraphic unconformities
are much greater on the northeast flank OF
the Manitoba Saska tchewan geosyncline than
in the balance Of the region. In this area
the Devonian Is Immediately overlain by the
Dakota sandstone Of the Cretacious. This ie
overlain by marine shales Of the Benton ana
Niobrara, which in turn are covered ny snaieY
of Pierre age. In the western portion ana
west central Saskatchewan, Belly River over
lies the Pierre, and in the southern ana
central portions OF the region, in places,
formations equivalent to the Lance and Fort
Union beds are encountered. In the eastern
portion of the territory the OrdoVician con-
sists Of lower sandstone known as tne
Winnipeg sandstone, which in wells penetrated
near Mafeking, Manitoba, consists OF so feet
Of coarse quartz sand. considerably indu-
rated Above this is the Lower Notified lime
stone with q thickness of approximately 10
feet. Above this is the Cat Head limestone
OF a similar thickness. Above the Cat Head
limestone lies the Upper Mottled limestone
with thickness OF $50 feet. Above the upper
Notified limestone lie the Stony Mountain
shales which are composed Of alternating Varl-
colored limestones and shales. This forma-
ton has an average thickness Of $50 feet. 1t
has not been penetrated by any wells drilled
in the western portion Of the region, as lar
as is definitely determined
Above the Ordovician the 5ilurian may be
found the base Of which is characterized by
conchidIi decussatum contained in q DUH
dolomitic limestone Of approximately 1856 feet
thickness Above the limestone occurs
gypsiferous horizon Of approximately lb0-foet
thickness, very often associated with saines
either in the form Of brines or as solids. Above
this gypsum zone lies q tough greyish dolo-
mitic limestone characterized by leperdita
hisingeri with an average thickness OF 100
feet In various places, ct the base OF the
Silurian and top Of the Ordovician, sand
stone or a sandy dolomite is encountered.
This was not observed In other wells in the
Mafeking wells, but has been observed In
other wells In the Central Plains. II was OBJ
served in the Commonwealth No. wen at
Manitou in southwestern Manitoba. In this
well oil saturated sandstone was found at the
base OF the Silurian with saturated sandy
dolomite at the top Of the Ordovician and II
is possible that such sands may be locally
discovered in q considerable portion OF the
area covered by this report. This formation
has been penetrated in several wells drille4
in the Central Plains, and probably in some
Of the wells drilled In Saskatchewan, such as
the Unity No. /, near Vera. In the western
portion Of the region the Paleozoics as well
as the upper formations have thickened very
considerably, but in the eastern portion the
Devonian consists OF hmestones dark shales,
and sands with some dolomite and has a