Soil/Landform Unit 79

Paleogene sediments from which many gravel extraction pits are located

Area:

8561 ha

0.64% of CMA region

Inland from Point Addis and extending west as far as Wormbete Creek, flat-topped hills represent the remnants of an extensive former ferruginised plateau. Small remnants are also found further north towards Moriac. Over most of this landscape ferruginised profiles are present, indicating former climatic conditions different from those experienced today. Where the Palaeogene sediments contain excessive amounts of gravel, ferricrete profiles are absent, but there is evidence of deep weathering and

leaching

. The soils are generally infertile, carrying a vegetation of stunted woodlands of

Eucalyptus obliqua

and

E. radiata

, The cinnamon fungus,

Phytophthora cinnamomi

, is very common on these plateau remnants and large areas of dead and dying native vegetation can be found. Many of these remnants remain uncleared and are used for flora and fauna reserves and some minor forestry operations. Gravel extraction pits have been established on suitable areas of Crown land. These pits will not revegetate quickly without appropriate management and have become popular with trail bike riders.

Gentle undulating slopes neighbouring the Otway Ranges
	E. obliqua and E. radiata of the plateau remnants

Component	1	2	3	4
Proportion of soil-landform unit	20%	7%	65%	8%
CLIMATE Rainfall (mm)	Annual: 600-850, lowest January (35), highest August (80)
Temperature (^oC)	Annual: 14, lowest July (9), highest February (17)
Seasonal growth limitations	Temperature: less than 10^oC (av.) July Precipitation: less than potential evapotranspiration mid October-early April
GEOLOGY Age and lithology	Ferruginised Neogene fluvio-marine sand, minor Palaeogene fluvial sand, gravel and clay and Recent aeolian siliceous sand
Geomorphology	6.2.4 Plains, rises and low hills of the Sedimentary Western Plains and 3.3.1 Dissected low hills plateaux of the Southern Uplands
LANDUSE	Uncleared areas: Hardwood forestry for posts, poles and firewood; nature conservationl passive and active recreation; gravel extraction Cleared areas: Beef cattle grazing on unimproved pastures; residential
TOPOGRAPHY Landscape	Flat or gently dissected plateau remnants
Elevation range (m)	50-230
Local relief (m)	10
Drainage pattern	Rectangular
Drainage density (km/km²)	1.4
Landform	Gently undulating plateaux
Landform element	Crest and slope	Slope	Broad flat crest and slope	Swale and broad depression
Slope and range (%)	2 (0-8)	2 (0-3)	2 (0-5)	1 (0-3)
Slope shape	Convex	Irregular	Linear	Concave
NATIVE VEGETATION Structure	Woodland	Woodland	Open forest	Open forest
Dominant species	E. obliqua, E. radiata, E. ovata	E. radiata, E. nitida, E. obliqua	E. obliqua, E. baxteri, E. radiata, E. aromaphloia	E. ovata, E. viminalis
SOIL Parent material	Quartz gravel, sand, some clay	Siliceous sand	Ferruginised sediments	Alluvial sand, clay, silt and plant remains
Description (Corangamite Soil Group)	Stony brown, grey or yellow gradational soils (17)	Grey sand soils (16)	Mottled brown, grey, yellow and red texture contrast soils with ironstone (13)	Yellow-brown texture contrast soils, coarse structure (15)
Soil type sites	MM5117, OTR741	OTR742	OTR601	OTR499
Surface texture	Gravelly loamy sand	Loamy sand	Loamy sand	Fine loamy sand
Permeability	Very high	Very high	Moderate	Very low
Depth (m)	>2	>2	1.2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Low inherent fertility and high permeability lead to leaching of nutrients.	Low inherent fertility and high permeability lead to leaching of nutrients. Weakly structured sands with low water holding capacities are prone to wind erosion.	Low inherent fertility, phosphate fixation and leaching of permeable upper horizons lead to nutrient decline.	High seasonal watertable and weak surface structure lead to surface compaction.

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