Fig. 23.1. Mountain basins and uplifts of Montana. See Fig. 23.2 for structural details of central 

 Montana. The Sweetgrass arch includes the Kevin-Sunburst dome and the South arch. The Genou 



trend is a relief feature of the Precambrian surface which was buried by onlapping Cambrian 

 and Devonian strata (Alpha, 1955). 



