A Taxonometric Analysis of Landform–Soil Particle Size Relationships in the Catchment of Linthorpe Creek,Darling Downs Southeast Queensland

Cluster analysis of randomly sampled soil materials on the basis of their detailed particle size properties shows that the materials form statistical clusterings–called here ‘textural groups’. Soil materials comprising the textural groups are also clustered spatially, and are hence mappable. Textural groups with geomorphic significance are recognizable at two hierarchical levels in the Q-mode cluster dendrograms, and indicate that the spatial variability of soil particle size can be envisaged as existing at two levels of scale. All textural groups demonstrate a consistent relationship to five landform types of crests, hillslopes, pediments, flood plain and infilled channels. At the higher hierarchical level, two major groups divide valley-side slopes at the pediment head into two topographically and genetically distinct zones–one of crests and hillslopes, and the other occupying pediments and flood plain system. At the lower hierarchical level, soil materials from crests, hillslopes and infilled channels form largely separate groups, while the pediment and flood plain deposits combine to form a further group. Boundaries between groups at both higher and lower hierarchical levels represent major and minor discontinuities respectively in the downslope variation in soil particle size properties.