The GCAS merged datasets are the result of re-gridding and merging the sixteen GCAS TMI, radiometric and DEM surveys' located data, using a single consistent gridding algorithm and spatial origins for each data type. The gridding method used for the subject radiometric spectral grids was minimum curvature with tension (0.2). The gridding was performed in the GDA94 geodetic coordinate system (which is consistent with the survey data capture flight lines' coordinate system) at 0.00036 decimal degrees (equivalent to 40 m cells). The grid origin of each of the 16 GCAS regions was carefully calculated to ensure that the resulting grids were co-nodular within the survey overlap regions, to eliminate or minimise the need for resampling during processing and merging. The located uranium, thorium and potassium channel data were reprocessed for DEM by Baigent Geosciences, to retain maximum signal and achieve the highest possible degree of internal consistency in relation to data calibration and processing across the broader GCAS survey region. Noise-adjusted singular value decomposition (NASVD) smoothing was incorporated into the processing stream, which is detailed in processing reports provided in a separate download package. The six derived map product, NASVD processed merged radiometric grid images are provided in the subject data package as ERS grids or tif images.