Soil/Landform Unit 172

Landform Unit Description

Unit 172 image a
Robinson et al. (2003) Corangamite Land Resource Assessment. DPI Victoria
Gently undulating sedimentary plains of a remnant plateau located north-east of Torquay
      Area: 9944 ha
      0.74% of CMA region

      These gently undulating plains occur as envelopes of Neogene fluvio-marine sand overlying various geologies in a number of areas across the region including Bannockburn, Torquay, Gheringhap, Maude and Lismore. These sedimentary plains of the dissected Western Plains support a wide range of vegetation classes including Plains Grassy Woodland, Plains Grassland/Plains Grassy Woodland Mosaic and Coastal Dune Scrub Mosaic. The dominant species vary from area to area along with the density and occurrence of vegetation classes. The low fertility and the low water holding capacity of the soils is an inherent limitation. Soils include an association of bleached brown, grey, yellow and/or red sandy mottled texture contrast soils or unbleached equivalents in better drained areas. Heavier surface textured soils may occur in drainage lines. These soils are prone to gully erosion which is minor to moderate in severity in some cleared areas along with sheet and rill erosion and waterlogging in wet seasons.
Unit 172 geomorphology

Unit 172 image b
The gently undulating plains have been extensively cleared and now support mainly grazing		Unit 172 cross section

Unit 172 graph
Unit 172 image c
Red highly ferruginised texture contrast soils exposed in a dam east of Torquay

Component
1
2
3
4
Proportion of soil-landform unit
60%
8%
7%
25%
CLIMATE
Rainfall (mm)

Annual: 580
Temperature (oC)
Minimum 9, Maximum 19
Precipitation less than potential evapotranspiration
October–April
GEOLOGY
Age and lithology

Neogene fluvial sand and minor marine marl, Quaternary basalt, Devonian granite
Geomorphology
LANDUSE
Uncleared: Nature conservation; hardwood; gravel extraction
Cleared: Sheep and beef cattle grazing; cropping (cereal); gravel extraction
TOPOGRAPHY
Landscape

Gently undulating sedimentary plains
Elevation range (m)
8–253
Local relief (m)
3
Drainage pattern
Dendritic
Drainage density (km/km2)
0.8
Landform
Undulating plains
Landform element
Upper plain
Drainage line
Lower plain
Long gentle upper slopes
Slope and range (%)
3 (2–5)
1 (1–2)
3 (1–5)
1 (1–3)
Slope shape
Straight
Concave
Straight
Straight
NATIVE VEGETATION
Ecological Vegetation Class

Plains Grassy Woodland (3.9%), Plains Grassland / Plains Grassy Woodland Mosaic (0.6%), Coastal Dune Scrub Mosaic (0.3%)
Dominant species
E. leucoxylon, Acacia pycnantha,
E. melliodora, Casurina stricta, E. viminalis
E. camaldulensis
E. leucoxylon, Acacia spp.
E. ovata, E viminalis, E. rubida, E. obliqua
SOIL
Parent material

Unconsolidated clay, silt, sand and gravel

Unconsolidated sediments and recent alluvial deposits

Unconsolidated clay, silt, sand and gravel

In situ weathered basalt
Description
(Corangamite Soil Group)
Mottled brown, grey or yellow and red texture contrast soils, both fine structured (13)
Mottled brown, grey or yellow texture contrast soils, fine structure (13)
Mottled brown, grey or yellow sodic soils, coarse structure (14)
Mottled brown, yellow or grey sodic texture contrast soil, coarse structure (14, 36)
Soil type sites
SW93, MM5012, SW99
Surface texture
Fine sandy loam
Sandy loam
Sandy loam
Clay loam
Permeability
Moderate
Moderate to low
Low
Moderate to low
Depth (m)
1.0–2.0
1.5–2.5
2
1.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS
Hardsetting surfaces and overland flow combine to create minor sheet erosion.
Seasonal high watertables, slope position and overland flow lead to periodic waterlogging and minor gully erosion.
Hardsetting surfaces and overland flow combine to create moderate gully erosion.
Hardsetting surfaces, dispersible subsoils and overland flow result in, leaching of salts, surface compaction, sheet and rill erosion and gully erosion.
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