Upper Mississippian-Lower Pennsylvanian Stratigraphy of Central Montana and Williston Basin

The principal area of study discussed in this paper is located in central Montana, and extends from the Little Belt Mountains on the west to Porcupine dome on the east. It is bounded on the south by the Bull Mountain syncline, and on the north by the Blood Creek syncline. This area has been referred to as the Central Montana Trough, or the Big Snowy Anticlinorium ... The secondary area of study is in Williston Basin proper, east from Porcupine dome and north to the Canadian border ...