Soil/Landform Unit - Rhymney hills

View south towards the low hills near Rhymnay with prominent strike ridges of the Ararat Hills

Area: 18 331 ha

0.78% of CMA region

These low hills and associated ridges and valleys of predominantly Palaeozoic metasediments occur as foothills flanking the Ararat Hills. There is high granitic terrain (Sugarloaf) to the north and lower erosional and depositional rises and alluvial plains to the west and north-east. Upper and lower slopes are major land components with strike ridges, flats and drainage lines. Drainage dissects this landscape, concentrating flow and increasing the susceptibility to gully erosion. Red texture contrast soil (generally

sodic

) and yellow and brown sodic texture contrast soils (

Sodosols

) occur on the lower slopes and flats (less drainage). Sheet and rill erosion, along with gully erosion are potential land threats given the texture contrast nature of soils. The hills are used for grazing (sheep, beef cattle), with occasional dryland cropping on the flats and lower slopes. Woodland communities such as Plains Grassy Woodland, Alluvial Terraces Herb-rich Woodland, Creekline Grassy Woodland, Granitic Hills Woodland and Grassy Woodland dominate remnant vegetation.

undulating rises and low hills
	Norval Dam surrounded by remnant vegetation

Component	1	2	3	4	5
Proportion of soil-landform unit	15%	15%	15%	35%	20%
CLIMATE Rainfall (mm)	Annual: 640
CLIMATE Rainfall (mm)	Annual: 640
Temperature (^oC)	Minimum 7, Maximum 19
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Cambrian basalt, andesite, boninite, rhyolite, gabbro and lithics; Cambrian marine sandstone, siltstone and biotite schist (St Arnaud Group); Neogene fluvial gravel, sand and silt
GEOLOGY Age and lithology
Geomorphology	2.1.2 Hills, valley slopes and plains on non-granitic Palaeozoic rock of the Dissected Western Uplands
LANDUSE	Uncleared areas: nature conservation Cleared areas: sheep and beef cattle grazing; dryland cropping
LANDUSE
TOPOGRAPHY Landscape	Undulating low hills
TOPOGRAPHY Landscape	Undulating low hills
Elevation range (m)	227-428
Local relief (m)	30–50
Drainage pattern	Dendritic
Drainage density (km/km²)	1.8
Landform	Strike ridges	Low hills
Landform element	Strike ridge	Drainage line	Flat	Upper slope	Lower hillslope
Slope and range (%)	17 (10-35)	5 (3-10)	2 (1-3)	8 (5-15)	5 (2-8)
Slope shape	Convex	Convex	Concave	Convex	Concave
NATIVE VEGETATION Ecological Vegetation Class	Grassy Dry Forest (38.7%), Grassy Woodland (27.4%), Alluvial Terraces Herb-rich Woodland (19.3%), Other (14.0%)
NATIVE VEGETATION Ecological Vegetation Class
SOIL Parent material	In situ biotite schist, marine sandstone and siltstone	Alluvial gravel, sand and silt	Fluvial gravel, sand and silt	In situ biotite schist, marine sandstone and siltstone, minor granite	In situ biotite schist, marine sandstone and siltstone, minor granite
SOIL Parent material	In situ biotite schist, marine sandstone and siltstone	Alluvial gravel, sand and silt	Fluvial gravel, sand and silt
Description (Corangamite Soil Group)	Red texture contrast soils (1)	Sodic yellow texture contrast soils (4)	Sodic yellow texture contrast soils (4)	Red texture contrast soils (1)	Red texture contrast soils (1)
Soil type sites	LP83, DOAGW31, LP82	GW28, GW30	GW28, GW30	LP83, DOAGW31, LP82	LP83, DOAGW31, LP82
Surface texture	Fine sandy loam	Sandy loam (silty)	Sandy loam (silty)	Fine sandy loam	Fine sandy loam
Permeability	Moderate to high	Slow	Slow	Moderate to high	Moderate
Depth (m)	< 0.5	> 2	2	1.2	1.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS Critical land features, processes, forms	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.	Light loose surface soils susceptible to periodic inundation, waterlogging and soil salinity. Sodic subsoil susceptible to gully erosion. Poor subsurface drainage, particularly on flats and drainage depressions. Surface soils susceptible to acidification.	Light loose surface soils susceptible to periodic inundation, waterlogging and soil salinity. Sodic subsoil susceptible to gully erosion. Poor subsurface drainage. Surface soils 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.	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.

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