Soil/Landform Unit 55

Looking across lava plains towards Mt Warrenheip with a blue stone quarry in the background

Area:

1104 ha

0.08% of CMA region

Within the Western Uplands are a number of swamps that are derived from a number of geological sources, the dominant being

Quaternary

lava plains and stony rises. These swamps and closed depressions host a wide variety of flora and fauna, many of which are protected species. Many of the swamps have been cleared and are used for grazing and cropping. Vegetation classes of these swamps include Plains Sedgy Wetland, Plains Grassy Wetland and Plains Grassy Woodland. Soils include the grey cracking clays on the lava plains, and black cracking clays associated with swamps and depressions of the stony rises. While waterlogging is the major limitation, soil

compaction

may also be a limitation to production without adequately controlled traffic. It should be noted that these swamps have been mapped due to their size with many other swamps identified as elements within alluvial plains.

Some blue stone quarries occur in the ancient deep paleochennels

Component	1	2	3	4	5
Proportion of soil-landform unit	10%	2%	65%	21%	2%
CLIMATE Rainfall (mm)	Annual: 810
Temperature (^oC)	Minimum 7, Maximum 17
Precipitation less than potential evapotranspiration	November-March
GEOLOGY Age and lithology	Quaternary clay; sand and gravel and basalt
Geomorphology	2.1.5 Alluvial terraces, floodplains and swamps of the Western Uplands
LANDUSE	Uncleared: Nature conservation; water supply Cleared: Cropping (cereal); sheep and beef cattle grazing
TOPOGRAPHY Landscape	Swamps and depressions in the north-east of the catchment
Elevation range (m)	409-569
Local relief (m)	1-2
Drainage pattern	Deranged
Drainage density (km/km²)	1.9
Landform	Terraces		Swamp and depressions	Gently undulating plains
Landform element	Terrace 1	Terrace 2		Long gentle upper slopes	Depression
Slope and range (%)	1 (1-2)	1 (1-2)	1 (0-1)	2 (1-3)	1 (1-2)
Slope shape	Straight	Straight	Flat	Straight	Straight
NATIVE VEGETATION Structure	Plains Sedgy Wetland (1.3%), Plains Grassy Wetland (1.2%), Plains Grassy Woodland (0.7%)
Dominant species	E. viminalis, E. radiata	E. viminalis, E. radiata	E. ovata	E. ovata, E. viminalis, E. rubida, E. obliqua	E. ovata, E. viminalis, E. rubida, E. obliqua
SOIL Parent material	Unconsolidated gravel, sand, silt and clay	Unconsolidated gravel, sand, silt and clay	Unconsolidated sands, silts and clays	In situ weathered rock	Basalt derived alluvium
Description (Corangamite Soil Group)	Dark brown soil - variable (34)	Yellow brown texture contrast soil (35)	Mottled dark grey, yellow gradational soil (34) and black clay soil, coarse structure (31)	Mottled brown, yellow or grey sodic texture contrast soil, coarse structure (36)	Black cracking clay soil, coarse structure (39)
Soil type sites	SW39, SW57, CLRA1	SW67, SW2, SW38	SW37, SW39	CLRA47, SFS6, MM5015	SFS2, CLRA46, SFS4
Surface texture	Fine sandy clay loam	Sandy clay loam	Light clay/clay	Clay loam	clay
Permeability	Moderate to low	Moderate to low	Low	Moderate to low	Moderate
Depth (m)	2	2	2	1.5	1.5
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Low-lying areas receiving drainage are prone to waterlogging. Overland flow may result in streambank erosion and gully erosion where soils are exposed.	Low permeability, weak surface structure and hardsetting surfaces make soils vulnerable to gully and streambank erosion, and compaction. Overland flow salinity may occur through subsurface flow.	Slowly permeable soils lead to waterlogging and compactin.	Hardsetting surfaces, slowly permeable subsoils result in overland flow. Periodic waterlogging occurs along with compaction of surfaces and minor sheet erosion.	Clay soils beside creeks are highly susceptible to, waterlogging, Streambank undercutting and streambank erosion occur where soils are exposed.

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