Increasing importance of the Virden-Roselea and North Virden oil-productive area has made it desirable that a workable subdivision of Lodgepole stratigraphy be undertaken for this area and for adjoining regions wherever correlation can be extended. The present paper proposes a stratigraphic subdivision of Mississippian Lodgepole of the Virden-Whitewater region into units of member rank, which are herein described and named in ascending order, the Scallion, Virden, and Whitewater Lake members. In addition, a fourth unit of limited preserved geographic extent is herein described and named the Routledge shale.

Due to lithologic variations resultant from changes in depositional environment within the preserved portion of the Lodgepole of the eastern Williston basin, the proposed stratigraphic units are applicable in general only to the eastern portions of the Manitoba and northern North Dakota sections. Recognizable correlation becomes increasingly difficult and unreliable westward of a northerly trending narrow zone of demarcation. The proposed subdivision into units of member rank is applicable throughout about 2,500 square miles in the Canadian area of study. Despite the limited regional extent of application, the economic importance of the area, including as it does the Virden-Roselea, North Virden, Southwest Virden, Routledge, South Regent, Whitewater, and Lulu Lake fields, warrants str tigraphic subdivision.