Abstract The natural gas industry of Montana became important with the development of the Cedar Creek (Baker-Glendive) anticline in 1915, but for 6 years development was slow. Since 1926 the development of the fields has been accompanied by the construction of pipe lines to other than local markets. As of August 1, 1933, there are 11 producing fields, 10 localities at which gas has been discovered but generally not produced excepting for local use, and several promising untested areas. This paper describes briefly the stratigraphy and geologic structure of the state. Synoptic descriptions of the important gas fields are given, covering the following subjects : producing horizon, geologic structure, proved area, number of wells, depth of wells, annual production, and total production. The controversial question of the gas reserve of the fields is not discussed. The gas fields briefly mentioned in this paper are: Cedar Creek (Baker-Glendive), Border-Red Coulee, Bowdoin, Bowes, Boxelder, Cutbank, Dry Creek, Hardin, Kevin-Sunburst, Lake Basin (Big Lake anticline), and Whitlash.

Abstract The area described here is in McCone County, Montana, approximately 100 mi (160 km) northwest of Glendive and 40 mi (64 km) south of Glasgow, on the east side of the Big Dry Arm of the Fort Peck Reservoir. It is located on the Jordan 1:250,000-scale map, the Fort Peek Lake East 1:100,000-scale map, and the Bug Creek 1:24,000-scale topographic map. The Bug Creek area (Fig. 1) is reached by proceeding south on Montana 24 for 24 mi (39 km) from the Fort Peck Dam or north 25 mi (40 km) from the intersection of Montana 200 with Montana 24. At this point a dirt road heads due west for 2.5 mi (4 km), then swings north at the rim of a mesa, and then swings south to the crossing of Bug Creek. The dirt road is passable by any vehicle when dry; four-wheel drive is required when the road is wet. The dirt access road is about 2.5 mi (4 km) south of the crossing of Montana 24 over the South Fork of Rock Creek and 5.5 mi (8 km) south of the road sign to Rock Creek State Park. More than 2 mi (3 km) west of Montana 24, the land is part of the Charles M. Russell National Wildlife Range. Much of the other land is controlled by the U.S. Bureau of Land Management (BLM); some is privately owned. Collection of vertebrate fossils on federal land is by permit only. No permission is required to examine exposures on federal or state land;

Abstract The outstanding structural feature of the Dakotas is the Williston basin. It is bounded on the east and southeast by gentle, rather featureless dips off the Canadian shield and the Sioux uplift and on the west by the abrupt Black Hills uplift and the lesser Baker-Glendive anticline of eastern Montana. More pronounced local structures are present in South Dakota, but the chief present interest in the petroleum possibilities of North Dakota is related to the regional structure. The combined area of the two states is approximately 100,000 square miles. The thickness of sedimentary rocks ranges from 1,000 to 12,000 feet or more. The average thickness is about 6,000 feet and the sedimentary volume is about 115,000 cubic miles. Subsurface structural information is available from seventy-nine wells, and thirty-two wells have been drilled into pre-Cretaceous beds. Not more than half of these wells were actual tests for oil and gas. The deepest test is The California Company's Kamp No. 1, drilled to 10,281 feet in Williams County, North Dakota. It stopped in either Ordovician or Devonian limestone. The percentages of different lithologic types in the sedimentary rocks vary widely through the area. Rough estimates for North Dakota are 45 per cent shale, 16 per cent sandstone, 37 per cent limestone and dolomite, and 2 per cent such evaporites as anhydrite and salt. For South Dakota, they are 66 per cent shale, 17 per cent sandstone, 16 per cent limestone and dolomite, and 1 per cent evaporites. A basal sand and shale