Nature, Distribution and Origin of Soils on an Alluvial Landscape in the Lockyer Valley, South-East Queensland

Abstract

Lockyer Creek and its major tributary, Tenthill Creek, have extensive alluvial landscapes up to 6 km wide. These are derived from the erosion of upslope Tertiary basalt, the argillaceous Jurassic Walloon Coal Measures and the Jurassic Marburg Formation which is predominantly sandstone. The alluvial landscape has been largely cleared of its original vegetation and is intensively cropped. To investigate the nature, distribution and origin of the alluvial soil landscape, a multidisciplinary study incorporating aspects of pedology, geomorphology and statistics was carried out. The geomorphology, and fine sand and clay mineralogy of upslope source materials and the alluvial soil landscape in the valley below were investigated and compared. Soils on alluvia along the major streams were found to have developed from predominantly basaltic sediment. Alluvial landforms of minor drainage lines were derived from mainly basaltic materials in upstream reaches, from upper Marburg beds in middle stream reaches, and from lower Marburg beds in downstream reaches.