The Scollard Formation was defined by Gibson (1977) and consists of sandstone, siltstone, mudstone, thin, discontinuous bentonites and thick coal seams (Ardley Coal Zone). Both the lower and upper contacts are unconformable. Evidence for an unconformity between the Scollard and underlying Battle Formation has been given by Russell (1983).
The presence of an unconformity at the upper contact with the Paskapoo Formation, postulated by Allan and Sanderson (1945), has been confirmed by Lerbekmo et al. (1990) on the basis of magnetostratigraphy and palynology.
The Cretaceous-Tertiary boundary, determined at the base of the prominent Nevis coal seam (likely equivalent to the Mynheer Seam) by Sweet and Hills (1984), divides the formation in two parts. The Tertiary upper part is generally referred to as the Ardley Coal Zone (discussed below), and the lower part is informally referred to as the barren zone and is Late Maastrichtian in age.
In the study area, the lower Scollard Formation is about 60 metres thick and dips to the southwest at about 30 m/10 km. The clastics of the lower Scollard are fluvial and barren of coal.
The name Paskapoo was introduced by Tyrrell (1887) for sandstone units above coal-bearing strata. Its stratigraphy has more recently been refined by Gibson (1977), Demchuck and Hills (1991) and Jerzykiewicz (1997).
The lower boundary of the Paskapoo Formation is defined as the erosional base of the first prominent sandstone above the Ardley Coal Zone and is an unconformity as described earlier. The Paskapoo Formation is Tertiary (Paleocene) in age. In the present study, only the lower 20 metres of the Paskapoo Formation were examined.