An informal subdivision of the Madison Group in subsurface of northeast part of Williston basin, ND, Saskatchewan, and Manitoba based on correlation of widespread mechanical-log marker horizons. Named for Midale oil field in Saskatchewan. No type locality designated. Lies between 4,572 ft and 4,648 ft in the Shell Midale A-7-18 well, Lsd. 7, sec 18, T6, R10, West 2nd Meridian, Saskatchewan. Bounded below by top of argillaceous band of dolomitic limestone terminating the [underlying] Frobisher-Alida beds, and above by top of another argillaceous band immediately underlying the Midale evaporite of Fuller, [J.G.C.M., 1956, Mississippian rocks and oil fields in southeastern Saskatchewan: Saskatchewan Department Mineral Resources Report 19]. Overlain by the Ratcliffe beds. Mississippian in age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

An informal subdivision of the Madison group, based on radioactivity- and electric-log correlations. Used in northwestern ND in the Williston basin. Lower contact defined in the sense of the Saskatchewan Geological Society (1956); upper contact raised to include the Midale Evaporite of Fuller [J.G.C.M., 1956, Mississippian rocks and oil fields in southeastern Saskatchewan: Saskatchewan Department Mineral Resources Report 19]. Shows correlations in oil and gas wells in cross sections extending from Divide Co eastward to Bottineau Co, and from Williams Co eastward to Bottineau Co, ND. Overlain by Ratcliffe beds; underlain by Hastings Frobisher beds. Mississippian in age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

An informal subdivision of the Madison group, based on radioactivity- and electric-log marker beds. Used in parts of Renville, Bottineau, and McHenry Cos, north-central ND, in the Williston basin. Lower contact revised upward to exclude an evaporite bed, placed by Anderson (1958) at the base of his Midale beds; upper contact drawn in the sense of the Anderson (1958). Is shown on a log of Carter-Phillips, G. Blower no. 1 well, SE1/4 SW1/4 sec 20, T160N [T161N], R83W. Overlain by the Ratcliffe beds; underlain by the M.C. 4 and M.C. 5 beds. Mississippian in age.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Pg. 1, 4 (fig. 3), 5-12. Midale subinterval (informal) in basal part of Ratcliffe interval (informal) in Madison group. = Midale beds of Anderson and Carlson (1958). Present in subsurface of the Williston basin, North Dakota. Consists of fine granular to sucrosic, light- to moderate-yellowish brown dolomitic limestone or limy dolomite, slightly argillaceous limestone. Underlies upper part of Ratcliffe interval; overlies Rivil subinterval (informal) of Frobisher-Alida interval (informal) in Madison group (Rivil subinterval corresponds to the lower part of the Saskatchewan Geological Society's (1956) Midale beds). Age is Mississippian. Log of the subinterval shown for the Pan American, B. Staaleson No. 1 well, in NW/4 NE/4 sec. 6, T. 162 N., R. 91 W., Burke Co., ND, and in five mechanical-log cross sections in Burke Co., ND.

Source: Publication; GNU records (USGS DDS-6; Denver GNULEX).

Midale subinterval (informal) in the basal part of Ratcliffe interval (informal) in Madison group. Defined by radioactivity- and electric-log markers; boundaries are same as those defined by Anderson and others (1960). Present in subsurface of the Williston basin, North Dakota. Consists of dolomitic limestone; thickness about 30 feet. Underlies upper part of Ratcliffe interval; overlies Rivil subinterval (informal) of Frobisher-Alida interval (informal) in Madison group. Age is Mississippian. Electric-log characteristics shown for the Carter-Phillips, G. Blower No. 1 well, in SE/4 SW/4 sec. 20, T. 160 N., R. 83 W., Bottineau Co., ND, and on a detailed electric- and radioactivity-log correlation diagram extending from Renville Co., ND southward to Sioux Co., ND.

Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).

Midale subinterval (informal) of Ratcliffe interval (informal) in Madison Group. Defined by radioactivity- and electric-log markers; boundaries are same as those defined by Anderson and others (1960). Present in subsurface of the Williston basin, North Dakota. Compares usage of the term by some previous authors in North Dakota and southeastern Saskatchewan. Summarizes stratigraphic relations. Age is early Late Mississippian (Meramecian), based on correlation with equivalent rocks in Canada. Electric-log characteristics shown for the Carter Oil Company, E.L. Semling No. 1 well, in sec. 18, T. 141 N., R. 81 W., Oliver Co., ND.

Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).