The formation of duplex soils on hillslopes in the Sydney Basin,Australia

Field studies of Duplex soils (Red and Yellow Podzolics or Ultisols) on hillslopes in the Sydney Basin show that their primary morphological feature (the texture contrast between A and B horizons) is explicable in terms of differential bedrock alteration combined with downslope movement of the coarser grained materials as a discrete surface layer. The more usually invoked processes of clay illuviation and/or clay destruction are of no more than minor importance in the genesis of Duplex soils in this area.