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14 Black, brown and grey strongly sodic and sodic mottled texture contrast soils on Neogene sediments

These soils are found on the gently undulating plains, rises or low level plateaux underlain by Neogene sediments (generally sands) which are generally unconsolidated but often have an indurated pan or layer on which the soils have developed.

The surface soil is generally dark with organic matter but light in texture (sandy loam) and between 10 to 20 cm in depth over a (generally) lighter coloured, often hardsetting subsurface horizon (10 to 30 cm in depth) of similar texture or lighter to the surface but containing much less organic matter. The subsurface horizon is often conspicuously bleached and may contain buckshot (ferruginous or ferromanganiferous nodules) of up to 50% volume of the subsurface horizon, occasionally more. These horizons abruptly contrast with a dark (black, dark grey or dark brown) upper subsoil with strong coarse structure (often columnar) which then grades into a pale/red mottled lower subsoil which grades into weathered sediments or ferruginised sandstone at about 150 cm (sometimes less depending on topographical and other factors). The dark upper subsoil is a result of organo-clay translocation from above coating the mottled soil aggregates or even replacing the mottle, and is a distinctive feature of soil development on this parent material.

Notable features include: the presence (or absence) of buckshot sitting on top of the subsoil, the sandy nature of the upper soil (occasionally unbleached and may be very coherent, loose or weakly coherent), strong sodicity of the subsoil (and possibly the surface soil as well) and related structural features, and the range of depth to parent material. The role of local climate, particularly rainfall, may influence soil development and such features as tiger mottles in weathered parent material are found further west in the CMA, while these soils tend to be in the drier eastern parts of the CMA.
CLRA Soil Unit 14

Soil Sites

Site Code
Soil-landform unit
1:100 000 mapsheet
Crest?, Mottled-Subnatric, Red SodosolDr3.42T7821 - Sorrento
-Magnesic, Subnatric, Yellow SodosolDr3.41T7622 - Ballarat
CrestFerric, Mottled-Subnatric, Brown SodosolDy3.43T7622 - Ballarat
FlatFerric, Mottled-Subnatric, Brown, SodosolDy3.42T7721 - Geelong
Simple slopeFerric, Mottled-Hypernatic, Black SodosolDy5.42T7721 - Geelong
Lower slopeVertic, Mottled_Hypernatric, Grey SodosolDy3.43T7721 - Geelong
Mid slopeCalcic, Mesonatric, Brown SodosolDy3.12T7721 - Geelong
Mid slopeMelanic, Mottled-Mesonatric, Brown SodosolDy5.22T7721 - Geelong
Mid slopeMelanic, Mottled-Mesonatric, Brown SodosolDb2021T7621 - Colac
Simple slopeVertic (& Calcic), Mottled-Hypernatic, Brown SodosolDb2.43T7721 - Geelong
Open depressionCalcic, Hypernatric, Brown SodosolDb1.43T7721 - Geelong
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