The Coal Bowl occurrence is located at the headwaters of the Omineca River, approximately 6 kilometres east of Saiya Lake. This prospect was explored by Suncor in the early 1980s. Reconnaissance and coal quality sampling was completed in 1981, followed by drilling and trenching in 1982-1984.
Coal-bearing strata are present in the upper units of the Middle to Upper Jurassic Bowser Lake Group and the Upper Cretaceous to Eocene Sustut Group. The oldest coals occur in the upper units of the Bowser Lake Group interbedded with sandstone, siltstone, mudstone, and shale. Nine seams of high to medium volatile bituminous coal occur in the Coal Bowl area.
The structure of the property is extremely complex and was affected by three separate orogenic events. The main folds, axes re-oriented northwest and paralleling the fault trends, include the Worthington and Vaux synclines and the Harp anticline. Folds within the Sustut Group are less complex and more open than those in the Bowser Lake Group. The main faults and thrusts also trend northwest. Minor east-west trending faults also occur but generally have small displacements.
The main faults are: the Saiya, Carruthers, Asitka, Main Creek, Coal Bowl, Watney and Bass faults. The Saiya, on the west boundary of the property, has a displacement of 200 to 500 metres. The high angle Carruthers thrust fault is located along the eastern boundary of the southeast block. The high angle, east-trending Asitka reverse fault has a displacement between 1000 and 2000 metres. The high angle Main Creek reverse fault has a displacement of approximately 1000 metres. The Coal Bowl thrust faults have displacements between 100 and 200 metres. The Watney and Bass faults, high angle reverse faults, have displacements between 100 and 1000 metres.
The main No. 1 through 9 coal seams all lie within the Coal Bowl area. The main No. 1 seam is very dirty, probably less than 1.0 metre thick, comprising 0.3 metre of coal. The maximum thickness of the main No. 2 seam is 3.90 metres, comprised of a 1.45 metre upper bench and a 1.55 metre thick lower bench. The seam thins to between 0.5 and 1.1 metres. The main No. 3 seam contains two benches and is locally split by additional thin shale and mudstone partings. The maximum thickness is 4.0 and 0.55 metres for the upper and lower benches respectively. The upper bench contains several shale and mudstone partings while the lower bench does not contain any. The main No. 4 seam is 0.6 to approximately 1.4 metres thick, thinning to the north. The main No. 5 seam, 5.0 metres thick, consists of carbonaceous shale with coal stringers. The main No. 6 seam is a 1.25 metre thick carbonaceous mudstone. The main No. 7 seam consists of two benches, upper and lower, 0.35 and 0.15 metres thick respectively. The main No. 8 seam is up to 1.3 to 3.55 metres thick. The main No. 9 seam, 4.1 metres thick, consists of an upper bench, 1.2 metres thick, and a lower bench, 2.10 metres thick.
The younger series of coals belongs to the Sustut Group and occurs in the southeast corner, the central and the northern parts of the Sustut block. These coals may be divided into 3 groups. The oldest coals, probably of Lower Tango Creek Formation age, are of high volatile bituminous "A" rank. The second group of coals continues from the oldest and are high volatile bituminous "B" in rank. The third group consists of three coal seams, Saiya A, B, and C, which are of sub-bituminous "A" rank, and belong to the Upper Tango Creek Formation.
