An extensive microfauna of over 25 genera and 40 species of arenaceous foraminifera occurs in the lower Sully Formation on the Sikanni Chief River and consists of Bathysiphon spp., Hyperammina sp., Saccammina spp., Lituotuba? sp., Glomospira sp., Ammodiscus sp., Reophax spp., Haplophragmoides spp., Bigenerina sp., Ammobaculites spp., Ammotium sp., Haplophragmium spp., Trochammina spp., Ammobaculoides sp., Textulariopsis spp., Gaudryina sp., Orientalia sp., Eggerella sp., Gravellina sp., Verneuilinoides sp., Uvigerinammina sp., Pseudobolivina sp., Dorothia sp., Miliammina spp., and Psamminopelta sp.The suite occurs below the fish-scale marker bed of the Cretaceous Colorado Shale within the uppermost Albian portion of the Neogastroplites Zone. The assemblage defines the Haplophragmium swareni Subzone of the Miliammina manitobensis Zone of the Colorado Group. It is correlative with the middle Mowry Shale fauna of Wyoming.The suite is deep neritic (200 m) with some suggestion of salinity lessened slightly below normal marine. It is accompanied by an extensive microflora of pollen, spores, and dinoflagellates. The suite represents biofacies intermediate between those previously found at similar stratigraphic horizons within the Cruiser Shale of the Moberly Lake area of British Columbia (a shallower fauna) and within the type Shaftesbury Formation of Peace River, Alberta (deeper, or farther offshore).