37°37'35"S x 144°25'44"E to 37°23'42"S x 144°19'06"E Gorge of Lerderderg River extending from Nolan Gully south to the Lerderderg ford.
Lerderderg State Park and the surrounding Wombat State Forest are north of Bacchus Marsh, around one hour's drive (90 km) (56 miles) from Melbourne on the Western Highway. Its myriad tracks, gullies creeks and ridges form a wild, rugged environment enjoyed by bushwalkers, horse riders and mountain bikers. The striking feature of this area is the 300-metre (975 feet) deep gorge that stretches south to the plains of Bacchus Marsh. Parts of the Wombat State Forest are still actively logged, and some areas are designated for domestic firewood collection with a permit. Many roads in the Lerderderg State Park are closed between June and the beginning of November as the park is within a water catchment area.
The park is popular for bushwalking, as it is possible to walk all day and not see anybody. The most popular areas to start a walk are from Mackenzies Flat Picnic Area and O'Briens Crossing. The best walk from Mackenzies Flat is one which goes up one side of the gorge and back along the other. It goes right up to the Lerderderg Weir. From O'Briens Crossing you can either walk up or down the river. Walking up takes you to The Tunnel. If planning a walk, make sure it hasn't rained much recently, and if walking along the river walk downhill, as the bushes on the riverbed always slope downwards.
From the East via Bacchus Marsh-Gisborne Road and Lerderderg Gorge Road for Mackenzie's Flat picnic area, from the south-west via Myrniong and Mt Blackwood, from the northwest via Greendale-Trentham Road and O'Brien's Road for O'Brien's Crossing. Whilst in previous years this often flooded, with the drought it is now quite safe to use.
Within the Lerderderg State Park and managed by Parks Victoria.
The Lerderderg Gorge is cut by the Lerderderg River into the blocks of the Rowsley, Greendale and Coimadai Faults. Side slopes are commonly of 350 to 400 metres (1,138 to 1,300 feet) with some vertical rocky cliffs up to 60 m (195 feet) high. The topography of the area is dominated by long narrow ridges and steep secondary spurs, with a high degree of rock outcrop on ridge crests, slopes and stream channels. Lower Ordovician sandstones and mudstones intruded by numerous small quartz veins form the dominant geology. The river descends steeply through boulders along a convoluted course with several steep-sided gooseneck meanders.
The Lerderderg Gorge is one of the major river valleys of Victoria
- O'Shaunessy, P. J., Hartland, R., and Bren, L. 1995. `A report on the effects of forest harvesting on water yield and quality in the Lerderderg Catchment'. Department of Conservation and Natural Resources, Research Report.
- Deformation in the Ballarat Slate Belt, central Victoria, and implications for the crustal structure across southeast Australia D. R. Gray; C. E. Willman Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia, 1440-0952, Volume 38, Issue 2, 1991, Pages 171 – 201
- Rosengren, Neville J. (1986). Sites of Geological and Geomorphological Significance in the Western Region of Melbourne. Melbourne: University of Melbourne. Dept. of Geography, Victoria. Dept. of Conservation, Forests, and Lands, Arthur Rylah Institute for Environmental Research. Ecological Inventory and Evaluation Section