Soil/Landform Unit 142

Near level plains or plateaux have relatively deep black and grey cracking clays. These soils have been used extensively for cereal production. The spread of local communities surrounding Geelong is an increasing land use of this unit

Area:

1723 ha

0.13% of CMA region

The black and grey cracking clays of these plains are heavily used for cereal and pasture production. Developed with well-defined drainage and deep regolith, this unit is derived from

Quaternary

volcanics that have capped underlying Palaeogene/Neogene sediments. Gentle to level plains characterise this unit with minor drainage depressions that have caused little dissection of these plains. As part of the Western Plains, the areas around Bannockburn and Lethbridge are experiencing residential development expansions in the wake of the communal growth of Geelong and neighbouring towns. The expansive and cracking nature of these soils is likely to pose foundation issues for housing and other forms of development. Erosion is primarily confined to the eastern slopes adjoining the steep slopes of the Moorabool River. Remnant vegetation is sparse with very little Creekline Grassy Woodland (0.1%) and Plains Grassland (0.6%). Species of the woodlands includes

Eucalyptus camaldulensis, E. leucoxylon

and

E. melliodora.

Cropping and residential development are major land uses
	Near level cracking clay plains near Bannockburn

Component	1	2	3
Proportion of soil-landform unit	50%	40%	10%
CLIMATE Rainfall (mm)	Annual: 580
Temperature (^oC)	Minimum 9, Maximum 19
Precipitation less than potential evapotranspiration	October-April
GEOLOGY Age and lithology	Quaternary basalt, Neogene fluvial sediments
Geomorphology	6.1.4 Volcanic Western Plains with well developed drainage
LANDUSE	Uncleared: Nature conservation Cleared: Cropping and grazing; residential development
TOPOGRAPHY Landscape	Near level basalt plains
Elevation range (m)	64-184
Local relief (m)	2
Drainage pattern	Dendritic
Drainage density (km/km²)	0.8
Landform	Plains
Landform element	Plain	Plan	Depression lines
Slope and range (%)	1 (1-3)	2 (1-4)	1 (1-2)
Slope shape	Straight	Straight	Concave
NATIVE VEGETATION Ecological Vegetation Class	Creekline grassy woodland (0.1%), Plains grassland (0.6%)
Dominant species	E. camaldulensis, E. leucoxylon, E. melliodora	E. camaldulensis, E. leucoxylon, E. melliodora	E. camaldulensis, E. leycoxylon, E. melliodora
SOIL Parent material	In situ weathered basalt	In situ weathered basalt	Alluvium mainly from basalt
Description (Corangamite Soil Group)	Mottled black and grey sodic texture contrast soils, coarse structure (35)	Black clay soils, coarse structure (39)	Black cracking clays, coarse structure (31)
Soil type sites	SW90, SW86, CLRA49	CLRA62, SFS2	CLRA48, SW37, CLRA35
Surface texture	Clay loam	Light to medium clay	Medium clay
Permeability	Very low	Very low	Very low
Depth (m)	1.0-2.0	0.5-1.0	1.5-2.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Surfaces can be responsible for high overland flow. Minor sheet erosion occurs on plains particularly close to scarps abutting neighbouring valley floors.	Self-mulching surfaces are cracking. Minor sheet erosion occurs on plains particularly close to scaprs abutting neighbouring valley floors.	Waterlogging of heavier soils likely in wet seasons. Minor sheet erosion occur on plains particularly close to scarps abutting neighbouring valley floors.

Page top