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Facies distributions, stratal geometry and regional erosional bevelling surfaces in Upper Cretaceous (Cenomanian‐Santonian) strata of the Alberta foreland basin are interpreted in terms of high‐frequency (probably eustatic) relative changes in sea level, superimposed on longer‐term basin‐floor warping, related to episodic tectonic loading. Thick marine shales correspond to periods of rapid subsidence whereas thin but extensive strandplain sandstones record rapid progradation during slow subsidence. Westward‐thickening wedges of coastal plain strata were deposited during initial downwarping of a near‐horizontal strandplain, prior to marine transgression. Surfaces of erosional bevelling beneath which between 40 and >160m of strata have been removed extend at least 300 km from the present deformation front and are interpreted to reflect forebulge uplift in the east. Uplift appears to have lagged about 0.25‐0.5 Myr behind the onset of accelerated loading. Thin marine sandstones which grade westward into mudstone are interpreted as material winnowed from the crest of the rising forebulge. Subsidence and/or westward migration of the forebulge allowed the sea to flood westward across the eastern flank of the eroded forebulge. The transgressive shoreface cut asymmetric notches which were later blanketed by marine shales which lap out from east to west. The two unconformities which embody the largest erosional vacuity are veneered locally with oolitic ironstone which accumulated in a shallow, sediment‐starved setting on the crest of the forebulge. The consistent pattern of erosional bevelling and lap‐out of transgressive shales might be interpreted as evidence that the forebulge migrated towards the thrust load over a period of <1 Myr.

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The morphology and dynamics of modern gravel shorefaces are poorly documented. This hinders the interpretation of possible ancient counterparts. A comparative study of a modern (Chesil Beach, England) and an ancient (Baytree Member of the Cardium Formation, Alberta) gravel shoreface shows that the two systems are very similar close to and above sea‐level, with a high (about 1 m) gravel plunge step lying below plane‐bedded sands and gravels of the beachface. The shoreface at Chesil Beach is dominated by asymmetrical gravel wave ripples. These are oriented offshore near the toe of the shoreface, and onshore in shallower depths. This may reflect offshore movement during storms and landward reworking during fair weather. The Baytree Member is over 12 m thick and comprises over 80% conglomerate. Conglomerate is decimetre‐bedded, massive or cross‐bedded, with sets over 60 cm thick produced by gravel bedforms migrating alongshore. It is interbedded with discontinuous cm‐ to dm‐bedded sandstones which may be cross‐bedded. Pebble fabric and cross‐bed orientation both indicate strong alongshore sediment transport. Near the base of the section, pebble orientations suggest that gravel wave‐ripples developed below the zone of strong longshore flows. Differences between these two examples may be attributed to different directions of wave approach.