Soil/Landform Unit 164

Limestone scarps and slopes at Scotts Creek

Area:

7911 ha

0.59% of CMA region

Rolling dissected low hills of the western Heytesbury region are derived from Miocene marine clay, marl and limestone. These rolling low hills occur from north of Scotts Creek through to Port Campbell. Steep dissection of the landscape has led to steep slopes and scarps with noticeable terracing prominent from lower broad drainage depressions and lines. This unit is a neighbour to the dissected rolling hills without cappings of soil-landform unit 165. Soils on these Miocene sediments are typically black, grey and yellow earths, with heavier earths found lower in the landscape. Limestone is often present at depth in the soil profile. Soils on these sediments are significantly more fertile than the sandy soils formed on the Neogene sediments of very few crests in this unit. Nearly all native vegetation has been cleared as part of the soldier settlement. Dairy farming is the main land use. Subsoils are dispersible and gully erosion has occurred along some drainage lines. Landslip and slumping is much less severe than of that in neighbouring soil-landform units 165 and 160. Drainage lines and lower slopes remain waterlogged for most of the year and can be prone to soil compaction (pugging) by stock.

Long straight slopes and scarps of the Port Campbell Limestone at Scotts Creek
	Quaternary basalt overlying Miocene Port Campbell limestone in the valley of the Curdies River

Component	1	2	3	4	5
Proportion of soil-landform unit	17%	5%	45%	25%	8%
CLIMATE Rainfall (mm)	Annual: 900-1000, lowest January (40), highest August (120)
Temperature (^oC)	Annual: 14, lowest July (9), highest February (18)
Precipitation less than potential evapotranspiration	November-March
GEOLOGY Age and lithology	Miocene marine marl and marine calcarenite
Geomorphology	6.2.2 Dissected plains, rises and low hills of the Sedimentary Western Plains
LANDUSE	Cleared areas: Dairy cattle; grazing beef cattle; sheep Minor uncleared areas: Nature conservation; includes forests at Timboon and Scotts Creek
TOPOGRAPHY Landscape	Roling dissected low hills with remnant plain cappings
Elevation range (m)	3-167
Local relief (m)	60
Drainage pattern	Parallel
Drainage density (km/km²)	2.6
Landform	Ridges	Fault scarps	Hillslops		Drainage lines
Landform element	Upper slope and crest	-	Mid slope and crest	Lower slope	-
Slope and range (%)	5 (2-9)	33	11 (4-21)	4 (1-7)	0 (0-1)
Slope shape	Linear	Linear	Convex	Concave	LInear
NATIVE VEGETATION Ecological Vegetation Class	Open forest	Woodlnad	Woodland	Woodland	Closed scrub
Dominant species	E. obliqua, E. ovata, E. aromaphloia	E. viminalis, A. melanoxylon	E. ovata, E. radiata	E. obliqua, E. ovata	M. squarrosa, L. lanigerum
SOIL Parent material	In situe marl and limeston	In situ marl and limestone	Clay with in situ marl and limestone	Clay and sand	Plant remnants, alluvial sand and clay
Description (Corangamite Soil Group)	Black calcareious gradational soils (22)	Black calcareous gradational soils (22/24)	Brown calcareous gradational soils, coarse structure (22/24)	Mottled brown, yellow and grey gradational soils (22)	Grey gradational soils (22)
Soil type sites	SW52, CLRA10, MM413	SW52, CLRA10, OTR489	OTR784	SW52, CLRA10, OTR413	OTR733
Surface texture	Clay	Clay	Loam	Sandy loam	Silty loam
Permeability	Moderate	Moderate	Low	Moderate	Low
Depth (m)	>2	>2	1.7	>2	>2
LAND CHARACTERISTICS, POTENTIAL AND LIMITATIONS	Highly dispersible soils of low permeability are prone to gully and sheet erosion. Low inherent ferility and leaching of permeable surfaces lead to nutrient decline.	Clay soils on steep slopes subject to periodic saturation are prone to landslips and sheet erosion.	Clay subsoils on steeper slopes subject to periodic saturation are pone to landslips, slumping of road batters and gully erosion.	Dispersible subsoils are prone to gully erosion.	Dispersible subsoil of low permeability receiving runoff from surrounding hills are prone to gully erosion, waterlogging and soil compaction.

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