13 Gey and brown (occasionally black, yellow or red) 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, often ferruginised) 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 25 cm in depth over a (generally) lighter coloured subsurface (A2) horizon (20 to 30 cm depth) of similar texture to the surface but containing less organic matter. The apedal subsurface horizon is often bleached and may contain buckshot (ferruginous or ferromanganiferous nodules) of up to 50% volume of the subsurface horizon. These horizons clearly contrast with a dark (black, dark grey or dark brown) strongly structured upper subsoil which then grades into a pale/red mottled lower subsoil which grades into weathered sediments or ferruginised sandstone at about 150 cm. 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, occasional unbleached horizon which may be loose or weakly coherent, some sodicity of the lower subsoil, red and pale mottling of the subsoil, and the range of depth to parent material (60–150+ cm). 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.

Soil Sites

Site Code	Soil-landform unit	Component	ASC	FK	1:100 000 mapsheet
CLRA72	77	Mid slope	Melanic-vertic, Eutrophic, Black Chromosol	Db2.31	T7821 - Sorrento
CLRA3	77	Mid slope	Bleached-sodic, Eutrophic, Grey Chromosol	Dy3.43	T7821 - Sorrento
MM358	187	Mid slope	Mottled, Mesotrophic, Brown Chromosol	Dy3.51	T7521 - Corangamite
MM361	170	Lower slope	Bleached-Mottled, Eutrophic, Brown Chromosol	Db2.41	T7521 - Corangamite
MM363	175	Upper slope	Bleached-Mottled, Eutrophic, Black Chromosol	Dd2.42	T7521- Corangamite
OTR492	190	Lower slope	Eutrophic, Mottled-Subnatric, Brown Sodosol	Dy3.41	T7721 - Geelong
OTR601	79	Mid slope	Ferric, Mesotrphic, Brown Chromosol	Dy3.11	T7721 - Geelong
OTR744	78	Hillcrest	Melanic, Mottled-Subnatric, Brown Sodosol	Dy5.22	T7621 - Colac
OTR783	161	Mid slope	Melanic, Dystrophic, Brown Chromosol	Db1.42	T7520 - Princetown
SW42	166	Upper slope	Melacic-Mottled (& Vertic), Eutrophic, Brown Chromosol	Dy3.32	T7521 - Corangamite
SW60	159	Crest	Reticulate, Mesotrophic, Brown Chromosol	Dy3.42	T7520 - Princetown
SW65	181	Flat	Reticulate, Mesotrophic, Brown Dermosol	Dy3.11	T7521 - Corangamite
SW66	170	Crest	Melacic-Mottled, Eutrophic, Brown Chromosol	Dy3.21	T7521 - Corangamite
SW67	170	Mid slope	Bleaced-Mottled, Eutrophic, Brown Chromosol	Db2.21	T7521 - Corangamite
SW68	170	Crest	Bleached-Mottled, Eutrophic, Brown Chromosol	Db2.41	T7521 - Corangamite

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