Soil/Landform Unit 112

Stony rises surround the base of Mount Elephant at Derrinallum

Area:

29 661 ha

2.22% of CMA region

The unit consists of an irregular surface of widespread basalt lava flows in which hummocks, depressions, ridges and blind channels have given rise to a completely confused topography. These stony rises occur along the Corangamite and Glenelg- Hopkins catchment boundary and have relief of less than 10 m. The stony rises are relatively recent basalt flows and have experienced little

regolith

and drainage development within the Western Plains. The rises are comprised of stony mounds that have shallow red and/or black loamy soils, numerous swamps with black cracking clays and gentle plains that are relatively rock-free with texture contrast soils. The only vegetation class of these plains is the Stony Rises Herb-rich Woodland. This unit is large and there are many equivalent areas within the Glenelg-Hopkins catchment. Other basaltic units and

alluvial

streams surround the stony rises. Land use is grazing (mainly sheep) with cropping on rock free plains and swamps. While the stony nature of soils is a major limitation, waterlogging is a productivity issue particularly on the former swamps due to their low relief and the impermeable nature of these soils.

An example of the dense nature of stony rises
	Relatively rock-free flats are highly productive, though waterlogging can be a concern

Component	1	2	3
Proportion of soil-landform unit	60%	30%	10%
CLIMATE Rainfall (mm)	Annual: 660
Temperature (^oC)	Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Quaternary basalt and minor alluvium
Geomorphology	6.1.2 Stony rises of the Volcanic Western Plains
LANDUSE	Uncleared: Nature conservation Cleared: Sheep and beef cattle; cropping (marginal)
TOPOGRAPHY Landscape	Lava plain with hummocks, depressions, ridges and channels
Elevation range (m)	113-302
Local relief (m)	30
Drainage pattern	Deranged-centripetal
Drainage density (km/km²)	0.7
Landform	Rise	Plain	Playa plains
Landform element	Undulating stony rises	Undulating plain	Basin depression and playa
Slope and range (%)	2 (1-4)	1 (0-3)	1 (0-2)
Slope shape	Convex	Straight	Concave
NATIVE VEGETATION Ecological Vegetation Class	Stony Rises Herb-rich Woodland (0.6%)
SOIL Parent material	In situ basalt	Basalt and colluvium	Basalt, colluvium and alluvium
Description (Corangamite Soil Group)	Shallow red or black loamy soils (40) and some black cracking clays (39)	Alkaline mottled brown or yellow texture contrast soils (36)	Black cracking clays (31)
Soil type sites	SW96, SW26, SFS2	SFS6, CLRA47, MM5015	SW37, CRLA47, SFS2
Surface texture	Clay loam light clay	Fine sandy clay loam	Light medium clay
Permeability	High	Low to moderate	Very low
Depth (m)	<0.7	<2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Loam (heavy) soils are shallow and friable. Low to moderate water holding capacity, moderate to high nutrient holding capacity. Some expansive clay soils. Often stony. Moderately rapid site drainage.	Texture contrast soil, low water holding capacity and moderate nutrient holding capacity in shallow surface and subsurface soils, higher in deep subsoil. Brown soils have moderate permeability, yellow (brown) soils have low to very low permeability. Strongly sodic subsoil, possible surface soil associated with poor drainage. Slow site drainage.	Uniform fine texture, expansive clays. High water holding capacity and nutrient holding capacity. Strongly sodic subsoil, possible surface soil associated with poor drainage. Some friable self-mulching surfaces wth high organic matter. Very slow site drainage.

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