Soil studies at Swan Hill, Victoria, Australia. IV. Groundsurface history and its expression in the array of soils

Abstract

This paper traces the events associated with the development of aeolian and riverine landscapes at Swan Hill. These phenomena are characterized by a sequence of alternations between unstable phases featuring erosion and deposition and stable phases during which soil development occurred. Four groundsurfaces were studied in the aeolian landscape. The unstable phases involved were sufficiently arid to result in a depletion of protective vegetation and allow the destruction of the previous groundsurface by erosion and burial. Inception of more humid conditions allowed the re-establishment of the vegetation. Aridity also extended westward from Swan Hill, but it was probably more severe to the west during the three earlier unstable phases than during the more recent one. Three groundsurfaces on riverine material were studied and it was considered that one of these could be subdivided into two layers. The unstable phases were characterized by deposition resulting in the burial of the previous groundsurface and evidence suggests that it also occurred during the more arid conditions rather than the more humid. There is a waning in magnitudes (as indicated by the degree of profile development) of both the unstable and stable phases from the earlier to the more recent groundsurfaces.