Soil/Landform Unit 169

Fertile and friable soils of the hillslopes are undergoing large land use changes as residential development further inhabits these slopes

Area:

387 ha

0.03% of CMA region

Located at Waurn Ponds, these sedimentary undulating low hills are derived from Paleogene marine clay (Jan Juc Formation). These marine clays are marls and calcarenites that are further exposed near Torquay in the major sea cliffs. As part of the Western Plains, this landscape serves as a stepping stone from the Barrabool Hills down to Geelong. The soils on these hillslopes are friable black gradational soils with good soil fertility and water holding capacity. Grassy Woodland is the major remnant vegetation, however the rapid rate of residential development in this area makes this vegetation even more vulnerable. While previously these fertile hillslopes and footslopes may have been used for cereal production (or potentially horticulture), little of this land remains for agricultural production.

Friable black gradational soils of the hillslopes are also found in the neighbouring alluvial Unit 192

Component	1	2	3
Proportion of soil-landform unit	20%	30%	50%
CLIMATE Rainfall (mm)	Annual: 620
Temperature (^oC)	Minimum 10, Maximum 19
Precipitation less than potential evapotranspiration	October-April
GEOLOGY Age and lithology	Paleogene marine clay, Recent clay, sand and gravel
Geomorphology	6.2.4 Plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Uncleared: Nature conservation Cleared: Residential development
TOPOGRAPHY Landscape	Undulating low hills
Elevation range (m)	39-120
Local relief (m)	75
Drainage pattern	Dendritic
Drainage density (km/km²)	0.9
Landform	Low hills
Landform element	Gentle crests, upper slopes	Mid slopes	Lower slopes
Slope and range (%)	4 (2-4)	1 (0-3)	0 (0-1)
Slope shape	Convex	Straight	Straight
NATIVE VEGETATION Ecological Vegetation Class	Grassy Woodland (2.3%)
SOIL Parent material	Clay, silt and sand	Clay, silt and sand	Clay, silt and sand
Description (Corangamite Soil Group)	Alkaline friable black gradational soils (29)	Alkaline friable black gradational soils (29)	Alkaline friable black gradational soils (29)
Soil type sites	CLRA13, SW40	SW40	CLRA15, SW40, CLRA13
Surface texture	Clay loam	Clay loam	Clay loam
Permeability	High to moderate	Moderate	Moderate
Depth (m)	<2	<2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Gradational. Friable. Moderate to high water holding capacity and nutrient holding capacity. Strongly structured, fine. Moderately rapid site drainage. Moderate compaction susceptibility when moist. Alkaline and maybe calcareous with depth.	Gradational, occasional texture contrast. Friable. Moderate to high water holding capacity and nutrient holding capacity. Strongly structured, fine. Moderate site drainage. Moderate compaction susceptibility when moist. Alkaline and maybe calcareous with depth, occasionally sodic.	Gradational, occasionaly texture contrast. Friable. Moderate to high water holding capacity, high nutrient holding capacity. Strongly structured, fine. Slow site drainage. Moderate compaction susceptibility when moist. Alkaline and may be calcareous with depth, occasionally sodic.

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