Glenthompson Duricrust Land Unit

This unit consists of the level to gently undulating duricrust surface around Glenthompson. The duricrust surface probably formed during a time of semi-arid climate in the Tertiary period, when evaporation and rainfall were nearly equal. Deep chemical weathering, has formed three distinct horizons. The upper horizon has a massive structure, dominated by oxides/hydroxides of iron and possibly aluminium and manganese. In many of these soils this has resulted in development of a petroferric horizon. The underlying horizon is noted for its mottled yellow, orange, red and purple colours. The deepest horizon is generally a pallid horizon of cream/white colour that has been kaolinised.

The soils on the near level plains tend to be Ferric Chromosols, although Ferric Sodosols do occur. Sodosols tends to be more dominant on the gently undulating landform. A minor soil type is a Ferric Brown Chromosol, which may be sodic at depth. There is commonly a layer of ferruginous nodules within the topsoil, principally in the A2 horizon. This layer can sometimes become cemented. This feature can be a major limitation for land use.