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Diabase (Db)

A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Diabase - geoArea: 30 sq. km (0.2%)

This land system is small in area, occurring on Cambrian, ultrabasic, volcanic rocks with pockets of chert and paper shales. It is found over a range of elevations along the Barkly River and near Mount Wellington. Considerable outcrop of massive diabase is common and in some areas rock outcrop and large boulders would severely restrict the movement of tracked vehicles. The areas are quite variable in their lithology and ecology but the topography is generally mountainous with a ridge-and-ravine dissection pattern.

Steep slopes and generally resistant rock have produced shallow, very stony soils of uniform loam to clay loam texture. Leaching under the high rainfall has been considerable and the soils are moderately acidic. The nutrient status however, is believed to be greater than that of similar soils derived from sedimentary rocks, for example those in Birregun land system.

    A study of the land in the Catchment of Gippsland Lakes - Vol 2 - land system Diabase - image
    Steep slopes along the Licola-Jamieson Road remain mostly uncleared
Moisture availability tends to he greater on the upper slopes at higher elevations and on the protected lower slopes of ravines. These sites carry vigorous open forest III, often layered or shrubby. Open forest II, with species more typical of drier conditions, occurs on slopes at lower elevations.

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

Annual 800 - 1400; lowest July (40 - 70), highest October (60 - 90)

Annual 8 - 12; lowest July (3 - 7), highest February (16 - 20)
Temperature <10C (av.): April - October
Rainfall < potential evapotranspiration: December - February; occasional winter snow
Age, lithology

Cambrian ultrabasic volcanic rocks and chert, paper shales and slates
Elevation range (m)
Relative relief (m)
Drainage pattern
Drainage density (km/km2)

Variable mountainous terrain; generally ridge-and-ravine topography

400 - 1240
220 - 640
PRESENT LAND USEUncleared: hardwood forestry (mainly second quality timber used mainly for general construction); apiculture; bush grazing of cattle

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

Percentage of land system
Diagnostic features
Slopes with humid forest
Slopes with drier forest, generally at lower elevations
Slope %, typical and (range)
Slope shape
40 - 50. (30 - 80)
40 - 50, (30 - 80)
Variable; ultrabasic rock including diabase; shale, slate, chert and associated rock types
Parent material
Dark coloured loam to clay loam merging into brown or reddish brown loam to clay loam. Generally shallow to very shallow with shallowest soils slopes; generally very stony not necessarily coincident with the steepest
Lithosolic Brown Earths, Lithosols
Um5.52. Um1.41, Um 1.44
Loam to clay loam
Surface texture
Soft to slightly hard
Surface consistence
0.2 -1.2
Depth (m)
Low to moderate
Nutrient status
Available soil water capacity
Perviousness to water
50 - 70 (generally)
Exposed stone (%)
Sampled profile (No.)
Structure of vegetation and characteristic species of dominant stratum
(+ Predominant species)
Limited data — probably shrubby or layered open forest III of E. obliqua+, often with E. cypellocarpa; E. delegatensis+ presumed at higher elevations
Open forest II:
E. goniocalyx+, E. macrorhyncha+

Affected process and trend
Primary resultant deterioration
Casual activities
Primary off-site process
Susceptibility of components
Incidence with components
    Alteration of vegetation:

    — reduction in leaf area, rooting depth and/or perenniality

    — reduction in density of tree roots
    Reduced transpiration.
    resulting in:

    a) increased deep percolation and leaching

    b) increased infiltration and regolith wetness

    Decreased root-binding

    Nutrient loss

    Soil creep

    Soil creep

    Not determined

    1: moderate
    2; low

    1; moderate
    2: low

    Not determined

    Not determined

    Not determined

    Removal of trees

    Accelerated by clearing of native vegetation

    Accelerated by clearing of native vegetation

    Increased movement of water to groundwater; increased base-flow of streams

    Increased sediment load

    Increased sediment load

    Increased exposure of surface soil
    Increased overland flow and soil detachment
    Sheet and rill erosion
    1.2; moderate
    Not determined
    Clearing, logging, burning, overgrazing, road building and other earth-moving activities,
    Increased flash flows and sediment load
    Increased physical pressure on soil
    Increased compaction


    Reduced infiltration
    Structure decline

    Sheet and rill erosion
    1,2: low

    Not determined

    Not determined
    Loss of organic matter from topsoil

    As for sheet and rill erosion above

    Increased flash flows
    Increased soil disruption
    Increased soil break-up
    Gully erosion
    1,2; low
    As for sheet and rill erosion above
    Increased sediment load.
    Comments: No observations of deterioration
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