These soils have developed on Quaternary unconsolidated material, generally of riverine, aeolian and lacustrine origin in the North West Dunefields and Plains, south of the Little Desert. The soil has a slightly acidic surface with a slightly acidic to slightly alkaline upper subsoil becoming strongly alkaline below. Variations may be influenced by climate variation.
The surface soil is usually a dark brown loamy sand which is apedal (massive or sandy) to weakly structured. It overlies a pale brown subsurface horizon which is bleached, apedal (massive or sandy) occasionally with ferruginous nodules (buckshot). There is a sharp/abrupt change to a brown to strong brown (occasionally yellow) medium heavy clay subsoil horizon. This is strongly structured (with coarse (columnar) to medium sized peds) and sodic. This overlies a pink, medium clay (fine sandy) horizon with a faint mottle, moderately structured (coarse sized peds), sodic and with variable free calcium carbonate. This soil grades into a reddish yellow mediuim clay, which is mottled before grading into weathered regolith (often sandstone). The profile depth is about 130 cm or more (at least 2 m) with variable depths of the surface horizons, generally 10 cm (5-20 cm) for the surface and 15 cm (5-30cm) for the subsurface, often deeper.
Notable features include:
- Texture contrast soil, subsoil is sodic.
- Variable surface condition (generally soft, occasionally hardsetting) with sandy surfaces.
- Strong consistence (strength) contrast between the lighter shallow surface and subsurface soil and heavy subsoil.
- Free (visible) calcium carbonate is common to dominant in mid subsoil.
- Subsoil mottling generally absent in drier environments, apart from transition to weathered regolith at depth.
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