This study is devoted to a detailed examination of the stratigraphy and petrology of the late Lower Devonian (Emisan) Buchan Group, an essentially carbonate sequence. The Buchan Group begins with the lenticular Spring Creek member of the Buchan Caves Limestone. This consists of terrigenous clastic sediments derived from erosion of the underlying Snowy River Rhyodacites. Lithologies range from conglomerates and breccias with rhyodacite pebbles, through arkosic sandstones to quartz sandstones and shales. Pyroclastics, previously identified in this unit, are absent. The Spring Creek member changed from non-marine to marine as the main transgression became established and was followed by a change to carbonate deposition.