The Jurassic system extends from the Williston basin into Manitoba where it unconformably lies on Paleozoic rocks and below Cretaceous sediments. It is divided into four formations, which are from the base upward; Amaranth, Piper, Rierdon, and Swift. An assemblage of gypsiferous red beds, anhydrite, and dolomite are included in the Amaranth formation. The remainder of the Middle Jurassic shales, argillaceous and oolitic limestones is placed in the Piper formation. The Upper Jurassic strata consist of the Rierdon formation which contains varicoloured shales and thin bands of limestone and the Swift formation which contains sand and shale beds. Depositional conditions and correlation problems related to the basal red beds, to the division between Middle and Upper Jurassic sediments, and to the upper limit of the Jurassic system are discussed.