At the Alexander Creek South prospect, phosphate, phosphatic shale, limestone and shale of the Jurassic Fernie Group unconformably overlie siltstone and minor shale of the Triassic Sulphur Mountain Formation (Spray River Group). The contact is marked by a 5 centimetre thick basal conglomerate. Phosphorite is 1 metre thick and contains 23.8 per cent P2O5 (Open File 1987-16). The upper extent of the phosphate interval is marked by a yellow-orange weathering marker bed. Faulting is abundant in the shale above the phosphate. Overlying the phosphorite are 1.6 metres of phosphatic shale and limestone containing 8.4 per cent P2O5.