This USGS report focuses on Cretaceous rocks in Montana with respect to natural gas and coalbed methane. The study includes the stratigraphy from the top of the Mowry Shale to the base of the Judith River Formation. The project integrates geologic, structural, hydrologic and engineering studies with known and new geochemical data on the gas and co-produced water. The report also facilitates an understanding of the controls on the spatial distribution of potential gas accumulations. Figures, tables, cross-sections and maps can be accessed in PDF format from this location.