Lower Jurassic Hazelton Group rocks of the Nilkitkwa Formation are exposed along Guess Creek. On the north bank of the creek, light grey medium-grained felsic tuff with quartz eyes hosts 3 per cent pyrite, disseminated and in fracture filling with minor chalcopyrite. Quartz-carbonate and chlorite veinlets crosscut the felsic tuff. In 1985, samples of the volcanic assayed 0.015 grams per tonne gold, trace silver, 0.1 per cent manganese, 0.075 per cent zinc, 0.03 per cent lead and 0.001 grams per tonne gold, 0.045 per cent copper, 0.7 per cent manganese, 0.06 per cent zinc and 0.02 per cent lead (Assessment Report 13638).
The eastern part of the claims host medium-grained, dark grey volcanic sandstone. Exposed in the southwest parts, is diabase which is chloritized with calcite fracture filling. Hematite is dissemi- nated as well as 5 per cent magnetite and pyrite.