Soil/Landform Unit 163

Around Cobden the occurrent of Port Campbell Limestone makes these broad crests sought after as a lime source

Area:

1096 ha

0.08% of CMA region

The gently undulating ridge crests near Timboon are characterised by broad sandy cappings with Herb-rich Foothill Forests including species of stringybark and messmate. This sedimentary unit of the Western Plains is located north of Scotts Creek in the Heytesbury area, and is deeply dissected to the north and west by the Curdies River (and associated streams) and other Neogene sediments (marl and limestone) to the east. This area is a major

area of dissection of Neogene sediments. Unit components are rise crests and upper slopes, and lower slopes on the rises, and drainage lines. The soils are acidic mottled brown texture contrast soils (Chromosols). Susceptibility to waterlogging occurs in the depressions but given the higher rainfall of the area and light surface soils, susceptibility to nutrient decline is high. Slight susceptibility to sheet erosion occurs on the slopes. Land use is intensive grazing (dairying) and some cropping.

Near-level top of these broad crests
	Miocene limestone underlying Neogene sediments at a quarry in the Curdies River

Component	1	2	3
Proportion of soil-landform unit	50%	42%	8%
CLIMATE Rainfall (mm)	Annual: 840
Temperature (^oC)	Minimum 9, Maximum 19
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Nepgeme fluvial_marine sediments, Recent clay, sand and gravel
Geomorphology	6.2.2 Dissected plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Uncleared areas: Hardwood forestry for sawlogs, posts and poles; water supply, nature conservation Cleared areas: Intensive grazing (dairying), some cropping
TOPOGRAPHY Landscape	Gently undulating ridge crests
Elevation range (m)	60-152
Local relief (m)	30
Drainage pattern	Rectangular-pinnate
Drainage density (km/km²)	0.7
Landform	Rises		Drainage lines
Landform element	Ridge crests and upper slopes	Lower slopes
Slope and range (%)	5 (3-10)	3 (2-6)	2 (1-4)
Slope shape	Convex	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Herb-rich Foothill Forest (20.8%)
SOIL Parent material	Sand, silt and clay	Sand, silt and clay	Clay, silt and sand
Description (Corangamite Soil Group)	Acidic mottled brown texture contrast soils (13)	Acidic mottled brown texture contrast soils (13)	Acidic mottled brown texture contrast soils (13)
Soil type sites	SW67, MM331, CLRA3	SW67, MM331, CLRA3	SW67, MM331, CLRA3
Surface texture	Fine sandy loam to clay loam	Fine sandy loam to clay loam	Fine sandy loam
Permeability	Low to moderate	Low	Very low
Depth (m)	<2	<2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possibly expansive clay subsoil, occasionall sodic. Moderately rapid site drainage.	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possibly expansive clay subsoil, occasionally sodic. Moderate site drainage.	Large texture contrast, low nutrient holding capacity and water holding capacity in subsurface and surface soil, higher in subsoil. Acidic (not quite strongly). Heavy, possibly expansive clay subsoil, occasionally sodic. Slow to moderate site drainage.

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