Junction Track Land System

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The junction between Cretaceous and Tertiary sediments on the western periphery of the Otway Range is clearly reflected in vegetation changes. However, the junction is discontinuous and there is a belt of land where the higher parts of the landscape are capped by Tertiary sands with only occasional areas of silts and clays derived from Cretaceous sediments. The lower slopes are often steeper, with outcrops of Cretaceous sandstones and mudstones. Thus, the higher areas carry low woodlands of Eucalyptus nitida and E. baxteri, while the lower slopes support open forests or even tall open forests of E. obliqua and E. cypellocarpa.

This landscape pattern is somewhat similar to the Redwater Creek land system. The major distinguishing feature is that the position in the landscape at which the Cretaceous sediments outcrop is very variable. The deposit of sand above the Cretaceous sediments varies in thickness, but is usually deep enough for the native vegetation to be dependent upon the sand for its nutrient supply.

Most parts of this land system remain uncleared and unused. Some sand and gravel extraction pits have been established in the past. Pines have been established on small areas adjoining privately held land.

A Study of land in the catchments of the Otway Range and adjacent plains - junction track

Most slopes support low woodlands of E. nitida, but outcrops of
Cretaceous sediments can be recognised by the increases soil
fertility and the accompanying change to open forests or tall open
forests of E. obliqua and E. cypellocarpa.

Area: 41 km²	Component and its proportion of land system
Area: 41 km²	1 30%	2 5%	3 20%	4 30%	5 15%
CLIMATE Rainfall, mm	Annual: 1,100 – 1,400, lowest January (55), highest August (150)
Temperature, 0^oC	Annual: 12, Lowest July (7), highest February (17)
	Temperature: less than 10^oC (av.) May – September
	Precipitation: less than potential evapotranspiration late November – mid March
GEOLOGY Age, lithology	Paleocene unconsolidated sand, gravel, silt and clay				Lower Cretaceous sandstone and mudstone
TOPOGRAPHY Landscape	Dissected hills with broad gentle hill cappings on western periphery of the Otway Range
Elevation, m	30 - 270
Local relief, m	75
Drainage pattern	Dendritic with some radial areas
Drainage density, km/km²	3.5
Land form	Hill
Land form element	Crest, slope	Drainage line	Lower slope	Crest, slope	Steep slope
Slope (and range), %	15 (2-35)	3 (0-5)	9 (3-12)	12 (2-25)	30 (20-55)
Slope shape	Convex	Concave	Linear	Convex	Linear
NATIVE VEGETATION Structure	Low woodland	Closed scrub	Low open woodland	Open forest	Tall open forest
Dominant species	E. nitida, E. baxteri	Leptospermum juniperinum, Melaleuca squarrosa	E. baxteri, E. nitida	E. baxteri, E. obliqua, E. radiata, E. nitida	E. obliqua, E. cypellocarpa
SOIL Parent material	Quartz sand and gravel	Alluvial sand, plant remains	Quartz sand and gravel	Clay, silt, sand and gravel	In-situ weathered rock
Description	Grey sand soils, uniform texture	Black sand soils, uniform texture	Grey sand soils with hardpans, uniform texture	Yellow gradational soils, weak structure	Brown gradational soils
Surface texture	Loamy sand	Silty loam	Loamy sand	Sandy loam	Fine sandy clay loam
Permeability	Very high	High	Very low	High	Moderate
Depth, m	>2	>2	1.1	>2	1.5
LAND USE	Uncleared areas: Sand and gravel extraction; hardwood forestry for posts, poles, fuel and some sawlogs on more fertile soils; nature conservation; water supply protection
SOIL DETERIORATION HAZARD Critical land features, processes, forms	Very low inherent fertility and high permeability lead to nutrient decline. Steeper slopes with compacted soils are prone to sheet, rill and scour gully erosion.	High water tables lead to waterlogging.	Hardpans restrict vertical drainage leading to seasonal waterlogging. Very low inherent fertility, with some leaching of permeable high acidic surfaces, leads to nutrient decline.	Low inherent fertility and high permeability lead to nutrient decline. Weakly structured soils on steeper slopes are prone to sheet erosion.	Clay subsoils on steeper slopes subject to periodic saturation are prone to landslips. Soils of moderate permeability on steep slopes are prone to sheet erosion.