The Australian Creek showing occurs within an area underlain by Tertiary sedimentary and volcanic rocks resting on older deformed rocks of the Cache Creek Group. The sedimentary rocks consist of sandstone, shale and conglomerate with interbedded tuff horizons, probably of Oligocene age, overlain by Miocene basalt flows. Outcrop is limited away from the incision of the Fraser River due to a cover of Pleistocene till.

The showing consists of a 1.5 metre thickness of thin bedded brown shale which occurs above a coal seam of the Oligocene Fraser River coal measures (refer to the Australian Creek Coal showing 093B 010). Also outcropping in the area is an 18 metre high bank of light grey, noncalcareous clay of cone 5.