Jurassic rocks underlie all of southern Alberta from its eastern and southern boundaries to the Rocky Mountain front on the west. The northern boundary is roughly crescent shape, approximately coinciding with the South Saskatchewan River and its tributary, the Oldman River, to within a few miles of Lethbridge. From that point the boundary trends northwest, passing a few miles east of Calgary. On Alberta plains, Jurassic strata are readily divisible into three formations, which were originally described and named in Montana, and which are, in ascending order, Sawtooth, Rierdon, and Swift. In Alberta Foothills, Jurassic strata are called the Fernie formation, which is roughly the equivalent of the three formations of the Plains.

Jurassic strata in southern Alberta rest unconformably on the Rundle formation of Mississippian age. On the Plains they are overlain unconformably by the basal sandstones of the Blairmore formation which have been correlated with the Cutbank and Sunburst sands of Montana. The unconformity at the top of the Jurassic truncates the formations so that they wedge out northward; consequently, the Swift, being the uppermost, has a very limited distribution in Alberta having been eroded completely from the crest of the Sweetgrass arch and remaining only in the extreme southeastern corner of Alberta and in a narrow belt paralleling the Foothills. The Rierdon and Sawtooth formations extend northward approximately to the limits of the Jurassic as defined. In the Foothills the Fernie is overlain y Kootenay sandstone and shale.

The Sawtooth formation consists of two sandstone members, separated by green, pyritic, non-calcareous shale. The upper sand is a reservoir for oil and gas in several small fields in Alberta. The formation has a maximum thickness of about 235 feet. The Rierdon formation is made up of an alternation of gray calcareous shale and greenish gray limestone with some pyrite, glauconite, and iron-stone, and has a maximum thickness of 200 feet. The Swift formation lies unconformably on the Rierdon and has a maximum thickness of 150 feet. It consists of glauconitic sandstone, siltstones, concretions, dark gray shale, and usually has chert pebbles at the base.

Facies changes take place from west to east in the Sawtooth, Rierdon, and Swift formations so that at the eastern boundary of Alberta they may be readily correlated with the Gravelbourg,

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Shaunavon, and Vanguard formations of Saskatchewan. However, they are not the exact equivalents of these formations since some overlapping occurs.

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