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McAdam (Mm)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- geoArea: 9 sq. km (0.1%)

McAdam land system occurs on the hard calcareous Devonian marine sediments which are restricted to a small area near Bindi in the north-west of the survey area. The rock here is the Buchan Caves Limestone, a much harder rock formation than the more mixed calcareous sediments of Bindi land system. The terrain is steep and mountainous with a ridge-and-ravine topography and rock outcrops where slopes cut across bedding planes. The mountains occur at low elevations.

Somewhat shallow clayey soils have formed on the steep slopes from the hard limestones. Soil reaction varies from slightly acidic to alkaline. Good surface drainage, moderate rainfall and low water-holding capacity allied with drainage fractures and solution channels in the bedrock. promote seasonal deficiencies in available water. The native vegetation. probably a grassy woodland I dominated by E. pauciflora with or without E. viminalis, has been almost entirely removed.
A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- image
Cleared slopes near Bindi

CLIMATE
Rainfall, mean (mm)
Temperature, mean (C)
Seasonal growth limitations

Annual 500 - 800; lowest July (30 - 50), highest October (50 - 80)

Annual 8 - 12; lowest July (3 - 7), highest February (16 - 20)
Temperature <10C (av.): May - September
Rainfall < potential evapotranspiration: November – March
GEOLOGY
Age, lithology

Devonian limestones, mainly Buchan Caves Limestone (Buchan Group)
PHYSIOGRAPHY
Landscape
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

Steep mountains with ridge-and-ravine topography

400 - 800
160 - 320
Dendritic
1.0
PRESENT LAND USEMostly cleared: grazing of beef cattle and sheep

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- csA study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Mcadam- graph

LAND COMPONENT
Percentage of land system
Diagnostic features
1
65
Long slopes parallel to rock bedding
2
35
Short steep rocky slopes cutting across bedding planes
PHYSIOGRAPHY
Slope %, typical and (range)
Slope shape
20 - 30. (10 - 50)
Straight
30 - 40. (20 - 50)
Straight to convex
SOIL
Parent material
Limestone
Description
Dark blocky or crumb structured clay loam to light clay grading into reddish brown or less commonly brown, blocky light or medium clay subsoil. In places very stony or with parent rock floaters; usually shallow. Component 2 has appreciable rock outcrop
Classification
Terra Rossa Soils. Lithosols
Uf6.12. Gn4.13
Surface texture
Clay loam to light clay
Surface consistence
Hard when dry, firm when moist
Depth (m)
<0.8
Nutrient status
Moderate
Available soil water capacity
Low
Perviousness to water
Moderate
Drainage
Good
Exposed stone (%)
Variable; 20 - 70
Sampled profile number
-
NATIVE VEGETATION
Structure of vegetation and characteristic species of dominant stratum
(+ Predominant species)
Grassy woodland I:
Upper slopes — E. pauciflora+
Lower slopes — E. pauciflora+, E. viminalis+

Disturbance
Affected process and trend
Primary resultant deterioration
Casual activities
Primary off-site process
Form
Susceptibility of components
Incidence with components
    Alteration of vegetation:
    — reduction in leaf area, rooting depth and/or perenniality
    Reduced transpiration,
    resulting in increased deep percolation
    Nutrient loss
    Not determined
    Not determined
    Removal of trees
    Increased movement of water to groundwater; increased base-flow of streams
    Increased exposure of surface soil
    Increased overland flow and soil detachment
    Sheet and rill erosion
    1,2; high
    Common
    Cultivation, overgrazing, road and dam building and other earth-moving activities, rabbit burrowing, trafficking by stock and vehicles.
    Increased flash flows and sediment load.
    Increased physical pressure on soil
    Increased compaction

    With


    reduced infiltration
    Structure decline



    Sheet and rill erosion
    1; high
    2; high
    (low for Lithosols)

    1,2; high
    Not determined
    Common




    Increased trafficking, overgrazing, export of organic matter
    As for sheet and rill erosion above



    As for sheet and rill erosion above
    -




    Increased flash flows
    Increased soil disruption
    Increased soil break-up
    Gully erosion
    I; high
    Uncommon
    As for sheet and rill erosion above
    Increased sediment load.
    Comments: Vegetative cover regenerates only slowly particularly on exposed aspects, because of the low water-storage capacity of the soils and the hot, dry summer - autumn season
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