The Early to Middle Triassic Nymboida Coal Measures outcrop over an area of approximately 90 km2 at the south-western margin of the Clarence‑Moreton Basin in NSW (Stewart and Alder, 1995). Throughout the remainder of the Clarence‑Moreton Basin in NSW, these Late Triassic coal measures underlie the Ipswich Coal Measures or the Bundamba Group where the Ipswich Coal Measures are absent, possibly occurring as restricted sediment packages within paleovalleys as suggested by seismic interpretations (Willis, 1994). Seismic data also suggest that the overall thickness of the Nymboida Coal Measures increases away from the basin margins and may exceed 1000 m in the central basin (Hartogen, 1983). Coal seams of the Nymboida Coal Measures are relatively thin (up to 2 m including non-coal bands; Wells, 1995) and discontinuous. The only seam of the Nymboida Coal Measures which was mined until 1979 at the Nymboida Colliery (Figure 4) is the Farquhars Creek Seam. The coal of the Nymboida Coal Measures is relatively high ash, medium volatile and bituminous coal with an exceptionally high calorific value (Stewart and Alder, 1995). An exploration programme by Waratah Coal Pty Ltd tested the resource potential of the Farquhars Creek Seam for underground mining of coking coal (Marketwire, 2007). Other seams within the Nymboida Coal Measures are lenticular, containing coal that approaches semi-anthracite in rank (Stewart and Alder, 1995).
Among the Nymboida, Red Cliff and Evans Head coal measures, the Nymboida Coal Measures are the only proven economic coal resources (Wells, 1995).