In the Dakota basin of North Dakota widespread Tertiary lignites and other beds are useful as datum points for structural contour mapping. An extensive stratum near the top of the Fort Union series, containing silicified plant stems, tree stumps, and volcanic ash is an excellent "marker-bed" for correlation.

There are present over wide areas in the basin Wasatch beds that were previously classed as part of the Fort Union series.

The structural configuration of the basin is considerably modified from that formerly postulated, in that the axis of another prominent syncline is shown, with a northwest-southeast trend roughly along the valley of the Missouri River from Sanish to and beyond Bismarck.

Several prominent anticlines, with northwest-southeast trends, are revealed in the surface Tertiary beds. Some have closures of more than 100 feet, where the regional northeast dip is only 7 feet to the mile. These are believed to offer favorable structural traps for oil and gas, where occurring in conjunction with possible traps of the stratigraphic type, due to the eastward and southeastward thinning-out of formations.

There is in the basin a thickness of approximately 12,000 feet of sedimentary strata, ranging in age from Tertiary to Ordovician, those of Ordovician age containing a thick section of porous zones with traces of oil, as revealed in the Semling well in southeastern Oliver County. This well is not a complete test of the oil and gas possibilities of the basin, especially as it is synclinal in its location on a minor surface structural feature.

An area almost as large as West Virginia has had no test wells and it is believed that the prospective areas outlined at comparatively low structural levels warrant drilling.

Drilling with rotary tools should not be unfavorably expensive as compared with some other deep regions.