Rocks of the Lower Cretaceous Blairmore formation extend over the whole of southern Saskatchewan. Along outcrop areas in western Manitoba, the Blairmore has undergone erosional truncation. Equivalent beds are found over almost the entire western interior plains of Canada and the United States. in southern Saskatchewan and adjacent western Manitoba the formation consists principally of fine to coarse quartzose sandstone, shale, salt and pepper sandstone, lignite, clay ironstone, kaolinite shale, and various mixtures of shaly sandstone and sandy shale. The Blairmore of the area is divided into five areal units and related to adjacent, more thoroughly studied areas. The divisions are: Mannville, Kootenai, Dakota, Swan River, and Ashville areas. The stratigraphy of each area is described and environment and source areas discussed. Oil in commercial quantities has been found in the Blairmore formation. The most likely areas of future exploration are suggested. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate