Several anthracite coal seams occur in the Sweeny Creek area in the Skeena Mountains, about 30 kilometres southwest of the significant anthracite prospects in the Mount Klappan area of the Groundhog coalfield (104H 020, 21 and 22), approximately 142 kilometres north-northeast of the community of Stewart.

The seams were identified in 1983 during regional reconnaissance and coal prospecting of lesser explored areas of the Bowser Basin by Esso Resources Canada. In 1984, Esso acquired coal licenses in the Sweeny Creek area and conducted 1:10,000-scale mapping. In 1985, some of the Sweeny area was dropped and trenching was conducted on seams in the remaining area and in the Konigus Creek area (104H 038) 19 kilometres to the south. Coal Assessment Report 714 recommended no further work in the Sweeny and Konigus areas, citing complex structure, abrupt facies changes and lateral discontinuity of seams, and the lack of economic seam thicknesses. The thickest seam found by the Esso exploration program is 1.57 metres. Rank is semi-anthracite to anthracite.

In 1991, Dawson and Ryan (Geological Survey of Canada Open File 2555) trenched and sampled three trenches in the Sweeny Creek area; two on a tributary on the east side of Sweeny Creek in the Jenkins Creek assemblage, and one in a tributary west of Sweeny Creek in the Skelhorne assemblage. Coal seam thicknesses ranged from 0.9 to 1.6 metres and vitrinite reflectance values (RoMax) ranged from 3.32 to 4.02 per cent (anthracite).

Strata in the Sweeny Creek area belong to the Upper Jurassic-Lower Cretaceous Bowser Lake Group. Esso Resources (Coal Assessment Reports 714 and 789) assigned the coal-bearing units to the Lower Cretaceous McEvoy Formation of Bustin and Moffat (Canadian Society of Petroleum Geologists Bulletin 1983). Placement of the Sweeny Creek area rocks in the McEvoy Formation was based on a rank study of the coals in the Currier and McEvoy formations by Bustin (1983) which observed vitrinite reflectance values of 1.7 to 3.5 per cent RoMax in McEvoy coals, and values of 3.0 to 5.8 per cent in Currier Formation coals. Samples collected by the Esso project yielded reflectance values in the range of 2.56 to 3.24 per cent RoMax. Evenchick and Thorkelson (Geological Survey of Canada Bulletin 577) assigned the rocks in the Sweeny Creek area to the Late Jurassic Skelhorne assemblage and the Jurassic to Lower Cretaceous Jenkins Creek assemblage. See Arctos (104H 021), located 24 kilometres east-northeast, for further discussion of the history of formation nomenclature of the Bowser Lake Group.