Soil/Landform Unit 107

Water infilled volcanic maar of Lake Bullen Merri near Camperdown

Area:

598 ha

0.04 % of CMA region

The maar complex in the south-west of the Corangamite catchment occurs near Camperdown and is associated with an eruption complex that includes low hills and plains (Unit

110

) and low hills and rises as scoria cones (Unit

). The water infilled maars comprise Lake Bullen Merri and Lake Gnotuk. As part of the volcanic Western Plains, the unit is characterised by steep to gentle inner rim slopes with water occupying the remainder of the unit. Associated with these inner slopes is the remnant vegetation class Scoria Cone Woodland. Soils are black texture contrast soils, are not

sodic

, have some

friability

and are better drained (particularly in the higher topographic positions), compared with the lower surrounding terrain, despite their texture contrast nature. Land use is mainly cropping and grazing along with nature conservation and water supply. The steep slopes are slightly susceptible to sheet and rill erosion.

Looking over Camperdown towards Lake Bullen merri
	Short inclined slopes of Bullen Merri

Component	1	2
Proportion of soil-landform unit	70%	30%
CLIMATE Rainfall (mm)	Annual: 800
Temperature (^oC)	Minimum 8, Maximum 18
Precipitation less than potential evapotranspiration	November-March
GEOLOGY Age and lithology	Quarternary scoria and Neogene marine sand, silt and marl
Geomorphology	6.1.1 Eruption points of the Volcanic Western Plains
LANDUSE	Uncleared: Nature conservation; water supply; active and passive recreation Cleared: Cropping; beef cattle and sheep grazing; regional development
TOPOGRAPHY Landscape	Maars and inner slopes of tuff rings
Elevation range (m)	100-260
Local relief (m)	70
Drainage pattern	Radial
Drainage density (km/km²)	1.1
Landform	Inner slopes
Landform element	Steep inner slopes	Lower moderate to gentle inner slopes
Slope and range (%)	25 (15-50)	10 (5-25)
Slope shape	Concave	Concave
NATIVE VEGETATION Ecological Vegetation Class	Scoria Cone Woodland (8.0%)
SOIL Parent material	Basaltic scoria and ash	Basaltic scoria and ash
Description (Corangamite Soil Group)	Neutral and acidic black mottled texture contrast soils (37)	Neutral black mottled texture contrast sols (37) and black cracking clays (31)
Soil type sites	SW25, MM227, SW27	SW25, SW48, SW37
Surface texture	Fine sandy clay loam	Fine sandy clay loam, light medium clay
Permeability	Moderate to low	Very low
Depth (m)	<1.5	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Texture contrst, moderate to high water holding capacity and nutrient holding capacity depending on depth and stoniness. Firable, non-sodic soils with fine to moderate struucture. Very rapid site drainage. Susceptible to sheet and rill erosion.	Texture contrast, moderate to high water holding capacity and nutrient holding capacity depending on stoniness. Friable, non-sodic soils with fine to moderate structure. Rapid site drainage. Some susceptibility to sheet and rill erosion.

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