Soil/Landform Unit 7

Low hills north of Haddon

Area:

1286 ha

0.10% of CMA region

North-west of Haddon are slopes of low hills situated on the western boundary of the Corangamite catchment. These low hills are primarily derived from

Ordovician

marine sandstone and shale bedrock with minor Recent clay, sand and gravel, and basalt. As part of the Western Uplands, this unit continues well into the Glenelg-Hopkins catchment. Soils are composed of mottled brown and yellow texture contrast soils (

Chromosols

and minor

Sodosols

) that may have surface soils with depths of 80 cm. There are minor occurrences of

mottled

brown soils with sporadically

bleached

subsurface horizons in better-drained areas. Native vegetation communities on these low hills include Plains Grassland/Plains Grassy Woodland Mosaic. Land use is mainly grazing for sheep and beef cattle with some cropping on lower slopes. The main hazards to land use are heavy subsoils that are occasionally sodic (causing gully erosion where exposed), sheet and rill erosion, and low subsoil permeabilities (low water holding capacity). Salinity as discharge also occurs within this unit.

View looking west-south-west from Smythes Creek towards Haddon
	Little remnant vegetation remains on the southern slopes of these hills

Component	1	2	3	4
Proportion of soil-landform unit	10%	35%	50%	5%
CLIMATE Rainfall (mm)	Annual: 640
Temperature (^oC)	Minimum 8, Maximum 19
Precipitation less than potential evapotranspiration	October-March
GEOLOGY Age and lithology	Ordovician marine sandstone and shale, recent clay, sand and gravel and minor basalt
Geomorphology	2.1.1 Dissected uplands with Palaeozoic sedimentary and metamorphic rocks of the Western Uplands
LANDUSE	Uncleared: Nature conservation; water supply Cleared: Sheep and beef cattle grazing; cropping (cereal)
TOPOGRAPHY Landscape	Undulating low hills
Elevation range (m)	150-455
Local relief (m)	40
Drainage pattern	Dendritic
Drainage density (km/km²)	2.0
Landform	Low hills
Landform element	Crests and ridges	Slopes	Rolling undulating plains	Drainage lines
Slope and range (%)	4 (1-7)	4 (3-10)	2 (0-5)	1 (0-3)
Slope shape	Convex	Convex	Convex	Concave
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassland/Plains Grassy Woodland Mosaic (9.0%)
NATIVE VEGETATION Ecological Vegetation Class	Plains Grassland/Plains Grassy Woodland Mosaic (9.0%)
SOIL Parent material	Sedimentary rock	Sedimentary rock	Sedimentary rock and colluvium	Colluvium and alluvium
SOIL Parent material	Sedimentary rock	Sedimentary rock	Sedimentary rock and colluvium	Colluvium and alluvium
Description (Corangamite Soil Group)	Acid and neutral mottled brown/grey or yellow texture contrast soils (25)	Acid and neutral mottled brown/grey or yellow texture contrast soils (25)	Acid and neutral mottled brown/grey or yellow texture contrast soils (26)	Acid and neutral mottled brown/grey or yellow texture contrast soils (26)
Soil type sites	BD10, CLRA53, CLRA58	BD10, CLRA53, CLRA58	BD13, BD11, MM204	BD12, BD11, MM204
Surface texture	Fine sandy loam	Fine sandy loam	Fine sandy loam	Fine sandy loam
Permeability	Moderate	Moderate to low	Low to moderate	Low
Depth (m)	<1	<1.5	<2	<2, >2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrast, low to moderate water holding capacity and nutrient holding capacity in surface and subsurface soil, moderate to high in subsoil. Rapid site drainage. Hardsetting surface, heavy subsoils with overland flow and leaching of salts common. Susceptibility to sheet and rill erosioon and compaction.	Texture contrast, low to moderate water holding capacity and nutrient holding capacity in surface and subsurface soil, moderate to high subsoil. Rapid site drainage. Hardsetting surface, heavy subsoils, overland flow, leaching of salts. Susceptibility to sheet and rill erosion and compaction.	Texture contrast, low to moderate water holding capacity and nutrient holding capacity in surface and subsurface soil, moderate to high subsoil. Rapid site drainage. Hardsetting surface, heavy subsoils with overland flow and leaching of salts common. Susceptibility to sheet and rill erosion and compaction.	Texture contrast, low to moderate water holding capacity and nutrient holding capacity in surface and subsurface soil, moderate to high subsoil. Rapid site drainage. Hardsetting surface, heavy subsoils with overland flow and leaching of salts common. Susceptibility to sheet and rill erosion and compaction.

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