Hordern Vale Land System

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In the vicinity of Cape Otway, Tertiary clay, silt, sand, limestone and marl all outcrop. Three separate areas exist – at Johanna, Hordern Vale and inland from Point Franklin and Blanket Bay. All areas are generally similar, but possess distinct differences in specific features. The limestone and marl outcrops are confined to marine terraces at Hordern Vale. The Johanna area is distinguished by its dominance of red sands. The area east of Cape Otway includes hilltops of kaolinitic clay and silt and these carry rare low woodlands of Eucalyptus kitsonia.

In general, these landscapes are old with areas of lateritized soils on the highest parts. Recent dissection has often been superimposed on the more undulating areas, resulting in straight slopes with youthful soil profiles.

Land uses are very diverse. Areas that have been cleared are used for dairy farming, grazing of sheep and beef cattle and a small amount of potato growing. Those areas that remain uncleared are selectively logged, and also have nature conservation values. Sheet erosion and landslips have been quite severe on some of the steeper areas, and some gully erosion occurs on the slopes coming away from the lateritized areas.

A Study of land in the catchments of the Otway Range and adjacent plains - hordern vale

Youthful dissection with steep straight slopes and young soils
is encroaching on many of the more gently undulating higher
parts of the landscape.

Area: 38 km²	Component and its proportion of land system
Area: 38 km²	1 20%	2 8%	3 7%	4 4%	5 25%	6 30%	7 6%
CLIMATE Rainfall, mm	Annual: 900 – 1,250, lowest January (50), highest July (130)
Temperature, 0^oC	Annual: 13, lowest July (9), highest February (17)
	Temperature: less than 10^oC (av.) July
	Precipitation: less than potential evapotranspiration late November - February
GEOLOGY Age, lithology	Paleocene unconsolidated sand, clay and silt
GEOLOGY Age, lithology				Limestone, marl
TOPOGRAPHY Landscape	Undulating coastal plains surrounding Cape Otway
Elevation, m	0 - 200
Local relief, m	60
Drainage pattern	Dendritic
Drainage density, km/km²	2.1
Land form	Rise	Valley floor		Rise
Land form element	Upper slope, crest	Slope, river terrace	Swale	Marine terrace	Steeper slope	Upper slope, crest	Rise
Slope (and range), %	5 (1-15)	7 (1-15)	0 (0-1)	25 (10-55)	30 (3-45)	8 (2-20)	3 (0-7)
Slope shape	Convex	Linear	Concave	Convex	Linear	Linear	Irregular
NATIVE VEGETATION Structure	Open forest	Open forest	Closed scrub	Woodland	Open forest	Tall open forest	Low woodland
Dominant species	E. obliqua, E. baxteri, E. cypellocarpa, E. aromaphloia, E. viminalis	E. obliqua, E. baxteri, E. viminalis, E. ovata	Leptospermum lanigerum	E. obliqua, E. viminalis	E. obliqua, E. cypellocarpa, E. baxteri	E. cypellocarpa, E. obliqua, E. viminalis, E. globulus	E. kitsoniana, Melaleuca squarrosa, Melaleuca ericifolia
SOIL Parent material	Lateritized sediments	Clay, silt and sand	Alluvial clay, silt and sand	Freshly weathered limestone and marl	Quartz sand	Clay, silt and sand	Kaolinitic clay, silt and sand
Description	Mottled yellow and red gradational soils with ironstone	Yellow-brown gradational soils, coarse structure	Grey gradational soils	Black calcareous gradational soils	Red sandy loam soils, uniform texture	Brown gradational soils	Pale brown gradational soils, weak structure
Surface texture	Gravelly sand	Fine sandy loam	Sandy loam	Fine sandy clay loam	Loamy sand	Fine sandy loam	Silty loam
Permeability	Moderate	Low	Very low	Low	Very high	High	Very low
Depth, m	>2	>2	>2	0.5	>2	>2	>2
LAND USE	Cleared areas: Beef cattle grazing; dairy farming; sheep grazing; row crops Uncleared areas: Hardwood forestry for sawlogs and pulpwood; sand extraction; nature conservation; passive recreation
SOIL DETERIORATION HAZARD Critical land features, processes, forms	Low inherent fertility and phosphorus fixation lead to nutrient decline	Dispersible subsoils are prone to gully erosion.	High seasonal water table and low permeability lead to waterlogging and soil compaction.	Clay subsoils on steep slopes subject to periodic saturation are prone to landslips	Steep slopes with weakly structured soils are prone to some sheet erosion. High rainfall and high permeability lead to nutrient decline.	High rainfall, high permeability and leaching lead to nutrient decline and surface compaction upon disturbance.	Low permeability and high annual rainfall lead to waterlogging and soil compaction.

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