Textural differentiation in chronosequences from eastern australia, I. Descriptions, chemical properties and micromorphologies of soils

• Published in: Geoderma Vol. 32; no. 3; pp. 181 - 202
• Main Authors: Chittleborough, D.J., Walker, P.H., Oades, J.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1984; Elsevier
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Soils; Surficial geology; Australia; Soils; New South Wales; Terraces; Alluvial soils; Soil; Horizons; Soil structure; Chemical properties; Alluvial plains; Texture; Micromorphology; Textures
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/0016-7061(84)90080-6

On flood plains and terraces of many rivers in southeastern Australia soil chronosequences have developed which show common trends in morphological and chemical properties. Four such chronosequences, comprising 17 profiles, were sampled to elucidate the processes involved in development of texture-contrasts. This paper is Part I of the study. From macro- and micromorphology and chemistry, it was concluded that the pedogenetic histories of the four chronosequences were similar. Following deposition of the parent material there was extensive homogenisation by soil fauna, obliterating sedimentary layers characteristic of the younger soils on the low alluvial benches and producing profiles relatively uniform in texture. Older soils on progressively higher terraces developed textural contrasts between A and B horizons. Clay illuviation appears to be the process responsible, but as the clay concentration increases in the B horizon the illuviated clays maximum shifts towards the base of the B horizon. The relatively low concentrations of depositional argillans in the upper B horizons of the older profiles may be caused by the disruptive effects of seasonal wetting and drying.