Soil/Landform Unit - Great Western rises

View south-west towards the Ararat Hills across Armstrong and the Great Western rises. Note the prominent gullying within this landscape

Area: 41 209 ha

1.76% of CMA region

Across the upper Wimmera River catchment exists a number of fringing sheets of capping material across underlying

Palaeozoic

bedrock. These undulating rises include preservation of this underlying bedrock as ferricrete and silcrete. As well as lining valley floors, these rises are discontinuous due to a series of drainage networks that have dissected these deposits. Locally relief tends to be less than 30 metres with slopes gentle to undulating. Soils are also variable with yellow to brown,

sodic

and non-sodic equivalent texture contrast soils (

Sodosols

and

Chromosols

) common. The rises represent local groundwater systems that are very slowly permeable with significant salt stores. Salinity discharge, scald erosion, gully and tunnel erosion are major land degradation issues. Land use is mainly grazing owing to poor soil water holding capacity of these soils, however cereal cropping has become more widespread recently. The main vegetation communities include Heathy Dry Forest, Grassy Dry Forest, Heathy Woodland, Plains Grassy Woodland, Alluvial Terraces Herb-rich Woodland, Grassy Woodland, Plains Woodland and Creekline Grassy Woodland.

Undulating rises of the Salt Creek catchment
	Grey box brown stringybark on Tertiary

Component	1	2	3	4	5	6
Proportion of soil-landform unit	18%	7%	25%	12%	30%	8%
CLIMATE Rainfall (mm)	Annual: 590
CLIMATE Rainfall (mm)	Annual: 590
Temperature (^oC)	Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration	October–March
GEOLOGY Age and lithology	Cambrian marine sandstone, siltstone and biotite schist (St Arnaud Group); Neogene fluvial gravel, sand and silt; Quaternary fluvial gravel, sand and silt
GEOLOGY Age and lithology
Geomorphology	2.1.5 Cainozoic landscapes of the Dissected Western Uplands
LANDUSE	Uncleared areas: water supply; nature conservation; gravel extraction Cleared areas: dryland cropping; sheep and beef cattle grazing; residential development
LANDUSE
TOPOGRAPHY Landscape	Foothills and footslopes
TOPOGRAPHY Landscape	Foothills and footslopes
Elevation range (m)	189–427
Local relief (m)	10–40
Drainage pattern	Dendritic
Drainage density (km/km²)	1.3
Landform	Rise–footslopes (Great Western 2)			Foothills–low hills (Great Western 3)
Landform element	Rise slope	Drainage depression	Plain	Hillslope	Footslope	Plain and drainage line
Slope and range (%)	5 (3-10)	2 (0-5)	3 (1-8)	15 (10-32)	5 (3-10)	2 (1--5)
Slope shape	Convex	Convex	Concave	Convex	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Grassy Woodland (42.2%), Heathy Woodland (20.5%), Alluvial Terraces Herb-rich Woodland (14.4%), Other (20.4%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	In situ sandstone, siltstone and biotite schist, minor granite	Fluvial gravel, sand and silt	Fluvial gravel, sand and silt, minor colluvial deposits	In situ sandstone, siltstone and biotite schist, granite	Colluvial and alluvial gravel sand and silt,	Fluvial gravel, sand and silt
SOIL Parent material		Fluvial gravel, sand and silt	Fluvial gravel, sand and silt, minor colluvial deposits	In situ sandstone, siltstone and biotite schist, granite	Colluvial and alluvial gravel sand and silt,	Fluvial gravel, sand and silt
Description (Corangamite Soil Group)	Sodic and non-sodic, yellow and brown texture contrast soils (5) and sodic and non-sodic, brown and red texture contrast soils (6)	Sodic and non-sodic, yellow and brown texture contrast soils (5)	Sodic and non-sodic, yellow and brown texture contrast soils (5) and sodic and non-sodic, brown and red texture contrast soils (6)	Red texture contrast soils (1) and sodic red texture contrast soils (2)	Sodic and non-sodic, yellow and brown texture contrast soils (5) and sodic and non-sodic, brown and red texture contrast soils (6)	Sodic and non-sodic, yellow and brown texture contrast soils (5)
Soil type sites	DOAGW15, WLRA141, WLRA142	DOAGW15	DOAGW15, WLRA141, WLRA142	LP83, DOAGW31, ALRA81	DOAGW15, WLRA141, WLRA142	DOAGW15
Surface texture	Sandy loam	Sandy clay loam	Sandy loam	Sandy loam	Sandy loam	Sandy clay loam
Permeability	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate
Depth (m)	2	> 2	2	0.7	2	> 2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	Hardsetting and soft surfaces susceptible to sheet and rill erosion even on gentle slope due to impeding layer (clay or hardpan). Subsurface soil and upper subsoil susceptible to compaction, and also gully erosion where sodic and deep. Topsoil may be susceptible to acidification.	Hardsetting and soft surfaces susceptible to sheet and rill erosion even on gentle slope due to impeding layer (clay or hardpan). Subsurface soil and upper subsoil susceptible to compaction, and also gully erosion where sodic and deep. Topsoil may be susceptible to acidification.	Hardsetting and soft surfaces susceptible to sheet and rill erosion even on gentle slope due to impeding layer (clay or hardpan). Subsurface soil and upper subsoil susceptible to compaction, and also gully erosion where sodic and deep. Topsoil may be susceptible to acidification.	Friable with better infiltration in moister areas, hardsetting and more prone to sheet and rill erosion in drier areas (north and westerly aspects). Susceptible to acidification in wetter areas. Sodic subsoil prone to gully and tunnel erosion.	Hardsetting and soft surfaces susceptible to sheet and rill erosion even on gentle slope due to impeding layer (clay or hardpan). Subsurface soil and upper subsoil susceptible to compaction, and also gully erosion where sodic and deep. Topsoil may be susceptible to acidification.	Hardsetting and soft surfaces susceptible to sheet and rill erosion even on gentle slope due to impeding layer (clay or hardpan). Subsurface soil and upper subsoil susceptible to compaction, and also gully erosion where sodic and deep. Topsoil may be susceptible to acidification.

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