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35 Black and grey strongly sodic texture contrast soils on Quaternary basic volcanics

These soils occur extensively on the basic volcanic plains, generally in the less stony areas. The organic surface soils (10–15 cm) overlie a weakly pedal to massive subsurface (A2) horizon (to 20–60 cm) with some ferruginous (or ferromanganiferous) gravel, which abruptly overlies a dark coarse structured hardsetting mottled (orange and yellow) heavy clay with some ferromanganiferous gravel, which may overlie a highly calcareous clay horizon (to 90 cm or greater) which will overlie parent material, usually with a clear boundary (>150 cm). Depth to horizon boundaries may vary due to the swelling nature of the soil, so that a subsurface horizon may not exist, with clay close to the surface, but then appear and be quite deep (and hence a greater depth to the heavy clay subsoil within metres of each other). This is called gilgai or crabhole terrain; the components are called puffs and shelves.

Notable features include: texture contrast, coarse structure (columnar), very hard when dry, strong sodicity in the subsoil and possibly the surface soil, variable vertical depth and horizontal distance characteristics of surface soil, free carbonate (calcareous) at depth, deep profiles, and some ferromanganiferous gravel.
CLRA Soil Unit 35

Soil Sites

Site Code
Soil-landform unit
1:100 000 mapsheet
Mid slopeEutrophic, Mesonaric, Black SodosolDd1.12T7621 - Colac
Upper slopeVertic, Mesonatric, Black SodosolDd2.13T7622 - Ballarat
FlatHypocalcic, Mottled-Hypernatric, Black SodosolDd2.43T7621 - Colac
Lower slopeCalcic, Mesonatric, Black SodosolDd1.13T7621 - Colac
Upper slopeHypercalcic, Mottled-Hypernatric, Black SodosolDd2.33T7621 - Colac
Lower slopeEutrophic, Mottled-Hypernatric, Black SodosolDd2.43T7622 - Ballarat
Upper slopeEutrophic, Mottled-Mesonatric, Grey SodosolDy3.33T7522 - Skipton
CrestCalcic, Mottled-Hypernatric, Grey SodosolDy3.33T7521 - Corangamite
CrestFertic, Mottled-Hypernatric, Grey SodosolDy3.43T7521 - Corangamite
FlatVetic (& Calcic), Hypernatric, Black SodosolDd1.13T7721 - Geelong
FlatVertic (& Calcic), Mottled-Mesonatric, Black SodosolDd2.23T7621 - Colac
Simple slopeCalcic, Mottled-Mesonatric, Black SodosolDd2.23T7721 - Geelong
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