3. Yarra Bend Park, Fairfield - Radial Basalt Columns

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

Sites of Geological and Geomorphological Significance in the Westernport Bay Catchment (1984) by Neville Rosengren.
Sites of Geological and Geomorphological Significance in the Western Region of Melbourne (1986) by Neville Rosengren
Sites of Geological and Geomorphological Significance on the Coast of Port Phillip Bay (1988) by Neville Rosengren.
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 (external link) section of the Geological Society of Australia website for details of geological heritage reports, and a bibliography.

Location:	YARRA 5000/05.07 E24510 N15470
	Left bank of Merri Creek near Fairfield Hospital 100 m west of Yarra Bend Park Road.
Access:	The site is difficult to access from the left bank due to the steep bank and the loose surface. It is best viewed from the right bank of the creek from the Merri Path opposite Walker Street.
Ownership & Municipality:	The basalt on the eastern side of the Merri Creek shows a complex fracture system in the basalt lava flows. At the base of the cliff are widely spaced vertical fractures cut by closely spaced horizontal joints. Higher in the cliff the vertical fractures are inclined and diverging and form a crude radial pattern. The persistence of sub-horizontal joints disrupts the continuity of the radial fractures and gives an irregular appears to the cliff face. A talus of broken and weathered basalt locks lies at the cliff base. The jointing is a result of cooling of the lava with the vertical fractures forming roughly at right angles to the upper and lower surfaces of the lava flow. It is possible there is more than one flow unit at this site.
Site Description:	Regional.
Significance Rating:	This is a good example of a radial fracture pattern in basalt lava flows and illustrates the complexity of jointing that occurs in basalt. It complements other sites that illustrate different fracture systems in the basalt exposed in the Merri Creek gorge downstream of Rushall Station.
Site Sensitivity:	Class 3.
	This is a robust site and the natural rate of weathering and site deterioration is low. It should be kept visible from the western (right bank) side of the creek by cutting back willows and shrubby weeds that obscure the visibility of the site. It is a potentially hazardous site due to a number of loose blocks on the cliff face and inherent instability of the fractured rock of the face. It may be safely and gainfully viewed from the right bank and this vantage point should be retained.
References:	None known.

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