A detailed sedimentological investigation of the Jurassic-Cretaceous Mist Mountain Formation in the southern Canadian Cordillera was undertaken to determine what, if any, sedimentological factors control coal quality and seam geometry. In the Line Creek area, the Mist Mountain Formation is divisible into two units based on abundance and lateral continuity of facies. The lower unit consists of alternating laterally extensive coal seams and thick, widespread channel sandstones interspersed with crevasse splay and flood plain facies sediments. The lower unit was deposited in an interdeltaic coastal plain environment protected from marine incursion by the beach ridge-dune sandstones of the underlying Morissey Formation. The upper unit of the Mist Mountain Formation was deposited in a distal alluvial-fluvial flood plain environment and has similar facies to the lower unit but coal seams and channel sandstones are less laterally continuous and thinner than in the lower unit. Channel sandstones decrease in number and thickness up-section, and are replaced by an increasing abundance of coal Seams, flood plain and crevasse splay facies sediments. Seam geometry and ash data indicate that elastic sedimentation had only Limited influence on pear (coal) accumulation in the Mist Mountain Formation. While the geometry of the seams reflects the proximity of under- and overlying channel sandstones, neither abundance nor mineralogy of the coal ash reflects changes in surrounding elastic sediments. The Mist Mountain Formation peat mires were thus not obviously influenced by coeval fluvial activity. Characteristics of the lower unit suggest pear mires developed only during hiatus in elastic deposition, whereas upper unit coals appear to have formed in at least partially domed mires contemporaneous with elastic sedimentation. The vitrinite content:of the coal increases up-section at the expense of semifusinite, possibly reflecting an increase in the proportion of arborescent vegetation in the mire with time and a lower susceptibility to fires. (C) 2000 Elsevier Science B.V. All rights reserved.