The Sustut Coal occurrence is centered on the upper and lower coal zones, approximately 23 kilometres west-southwest of Sustut Peak (Coal Assessment Report 115. Gulf Canada explored the prospect in 1980 with 5 hand trenches, mapping, and coal quality sampling and analyses (EMPR COAL ASS RPT 115).

The deposit is hosted in Middle to Upper Jurassic Bowser Lake Group sediments. To the east lies a thick succession of Jurassic to Triassic volcanic rocks of the Hazelton and Takla groups.

The structure of the area is dominated by thrust faults and overturned folds. Fold axes and fault traces generally trend northwest. Beds dip predominantly west, 30 to 40 degrees, but the southwest limbs of several synclines are steeper and often overturned. The folds are tight and commonly thrust faulted. Amplitudes vary from a few metres to several hundreds of metres. Anticlines tend to be closed, overturned and commonly broken while synclines are more open, though also frequently overturned. Two types of faults occur in the area; normal faults of considerable and negligible displacement and, most commonly, imbricate southwest- dipping thrust faults.

Coal occurs in two major zones in the upper portion of the middle (deltaic) unit of the Bowser Lake Group. The coal is low volatile bituminous in rank and occurs interbedded with claystone, siltstone, sandstone and conglomerate. The coal appears to be limited to the Australia Lake cirque.

The lower coal zone is 6.58 metres thick and contains two seams 0.68 and 3.27 metres thick. The upper coal zone is 14.34 metres thick and includes three seams; 1.09 metres, 1.42 metres and 2.86 metres thick.

The coal is restricted in lateral extent along both strike and dip. Average analysis for the raw Sustut coal is 38.2 per cent ash, 15.81 per cent volatile matter, 42.86 per cent fixed carbon, 0.35 per cent sulphur and a calorific content of 7949 BTU per pound. The resource potential of the Sustut coal licenses is approximately 63 million tonnes of raw coal (Coal Assessment Report 115).

Two other coal zones occur to the south of the upper and lower coal zones. One coal zone, about 4 kilometres away, consists of 0.52 metres of 'poor coal' striking 132 degrees and dipping 64 degrees to the northeast. The second coal zone, approximately 7 kilometres away, strikes 110 degrees and dips 33 degrees to the southwest. The total thickness of this zone measures 0.92 metres. The rank, determined from a thin coal seam within this zone, is medium volatile bituminous coal.