Abstract Thick (15 to 35 m, 49 to 115 ft) sandstones in the upper Mannville (Aptian to early Albian) in east central Alberta have several genetic origins. In the western part of the study area, thick sandstones have formed by the stacking of fluvial channel deposits. The variable thickness and irregular distribution of the sandstones on cross sections support the presence of multiple paleochannels. Oil saturation and reservoir pressure data corroborate this interpretation in the Hairy Hill area. In the eastern part of the study area, sandstones of similar thickness have formed by an amalgamation of channel and marine shoreline facies and by the stacking of crevasse splay deposits in brackish water bays. Ichnological and palynological data confirm that the upper Mannville becomes more marine in the eastern part of the study area. It is concluded that during upper Mannville time, the streams in the west were flowing into a marine embayment which lay to the east. Brackish water deposits have predictive value, as they signal the change from continental to marine sedimentation. Based on the upper Mannville, several criteria have been proposed for the interpretation of these environments in core. The presence of syneresis cracks, pyrite and siderite and a limited assemblage of certain trace fossils and marine microplankton together indicate a marginal marine setting. These criteria are complementary and represent a multidisciplinary approach which the authors advocate for the recognition of paleoenvironments.