34. Cracking clay soils/Clay plain with subdued ridges

These soils have developed on Quaternary unconsolidated material, generally of aeolian and lacustrine origin in the North West Dunefields and Plains, to the north of Horsham. They occupy plains and swales, and may occur in association with occasional vertic, sodic texture contrast soils. The Sodosols are associated with gilgai micro relief (Vertosol/Sodosol complex). The soil is alkaline throughout and calcareous.

The surface soil is usually a dark grey, light to medium clay. This is selfmulching, subplastic and has weak structure (coarse granular). There is a clear change to a dark grey (occasionally grey) heavy clay subsoil horizon. This is strongly structured with coarse to medium sized peds, occasionally slightly mottled and with few calcium carbonate segregations below the upper subsoil. This soil grades into a yellower heavy clay at depth. The profile depth is about 130 cm or more to the paler clay continuing below 2 m, with depth of the surface horizon generally about 10 cm.

Notable features include:
Cracking clay with highly self-mulching surface (high calcium content).
Surface generally friable (self-mulching or pedal), strong consistence (strength) when dry.
Very occasional bleached subsurface soil.
Mottled or pale subsoil at depth has restricted soil drainage, often strongly sodic and likely to be dispersive.
Occasional red or brown subsoil variants.