The Genou trend is a pre-Cambrian igneous structural alignment on which are located several structural highs visible on contour maps drawn on the Madison. The trend crosses the South arch of north-central Montana in a northeast direction, just south of Collins. This trend parallels the pre-Paleozoic and early Paleozoic structural features of the Canadian Shield in Canada and Minnesota. Geophysical evidence points to a similarly oriented structural fabric in the subsurface across central Montana and North Dakota.

Stratigraphic evidence indicates the age of the igneous emplacement as pre-Cambrian. Biostromes and probably some bioherm reefs occur on the trend. Oil shows are found in fractures, vugs, and pores throughout 80-420 feet of the basal Devonian section and in the top of the Mississippian, but the yield was only water with a rainbow of oil on drill-stem tests. The Swift sandstone is saturated with heavy black oil but also yielded nothing on tests.

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