Site 26 Barry Road Gorge, Campbellfield - Unconformity

This information has been developed from one or more of these publications:

Sites of Environmental Significance in the Flood Plain of the Upper Yarra Valley Region (1983) by Neville Rosengren, Douglas Frood and Kim Lowe (as part of a study of Sites of Environmental Significance by the University of Melbourne for the then Upper Yarra Valley and Dandenong Ranges Authority).

Geological heritage sites, including sites of geomorphological interest and volcanic heritage sites, are under regular revision by the Geological Society of Australia, especially in the assessment of significance and values.Reference should be made to the most recent reports. See the Earth Science Heritage section of the Geological Society of Australia website for details of geological heritage reports, and a bibliography.

Location:	YARRA 5000/04.12 E21400 N28150 to E21181 N28510
	Merri Creek valley extending for approximately 1 km south of Barry Road.
Access:	Barry Road, Ari Drive, Malcolm Place.
Ownership & Municipality:	Public Land, City of Broadmeadows and City of Preston, Melbourne Water.
Site Description:	The site includes cliffs, alluvial and bedrock terraces and minor floodplains. The major geomorphological and geological feature is a 15 m high cliff on the right bank of the Merri Creek. The cliff exposes an unconformity between the bedrock of Silurian sedimentary rocks and the Newer Volcanics basalts. The Silurian rocks outcrop in the channel of the creek and along with large fallen basalt blocks, form rapids and small cascades when the river is in high flow. A number of small potholes are eroded into the sandstone beds, some with basalt grinding pebbles still in place. In the cliff face can be seen the fossil soil developed on the Silurian rocks and now buried and baked by the lava flow. A calcareous precipitate forming a massive deposit on parts of the lower cliff is a result of carbonate rich waters issuing as springs at the base of the basalt. Different flow structures and joint patterns in the lava indicate more than one flow unit to be present in the cliff face. The northern parts of the site also provide very clear exposures of massive, jointed, vesicular and ropy lava. Zeolites up to 10 mm in diameter are infilling many cavities in the basalt rock. The slopes of the valley upstream of the steepest part of the gorge have 3 distinct terrace levels, the lower terrace being a bedrock terrace with alluvial veneer.
Significance Rating:	State
	This gorge is one of the most distinctive topographic features of the Merri Creek catchment and a major element of the landscape of the northern region of Melbourne. It is an outstanding example of an unconformity between basalt and the Silurian bedrock – a very common geological feature but one which may be seen in only a few localities. Both rock types and the contact in the cliff face on the right bank of the Merri Creek are well displayed and a number of related features (buried soil, ground water leakage and carbonate deposition) are also evident. The site is the best example of this geological feature in the Melbourne region and is a superior display than the better-known similar feature at Organ Pipes National park. When viewed in conjunction with the retarding basin and adjacent geological sites, it provides a complex of major geological and geomorphological significance. The site has the potential for an interpretation centre for the landscape of the Merri Creek along the lines of that at Organ Pipes National Park.
Site Sensitivity:	Class 2
	Broadly this is a robust site but positive action is needed to maintain diversity and enhance the considerable educational potential of the area. Apart from a massive weed control problem and clearing of rubbish and dumped vehicle debris, there is a need for roads and parking area, footpaths, viewing platforms and footbridges across the Merri Creek to give formalised and controlled access. There is a vandalism and security issue to be addressed. However, Organ Pipes National Park has demonstrated that reserves adjacent to urban areas can be rehabilitated. “Friends” groups along with naturalist and other organisations could be involved in this programme.
References:	None kown.

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