Bb2 Russells Bridge - Pillow Lavas

This information has been developed from the publications:

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 Geological and Geomorphological Significance in the Shire of Otway (1984) by Neville Rosengren.

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	Bannockburn - 522890. Former Shire of Bannockburn. 200 m north of Russells Bridge, 4 km south of Bannockburn.	Bb2 - Pillow lavas at Russells Bridge, Moorabool Valley.
Access	Bannockburn-Maude Road off Midland Highway.
Ownership	Crown land.
Site Description	The road cutting north of the bridge exposes an 8 to 10 m section in a lava flow of the Maude Basalt Member of the Maude Formation. Although somewhat weathered, the section displays well preserved pillow lavas. Large ovoid structures or pillows up to 1 m in diameter have a hard rim of volcanic glass surrounding decomposing basalt. The pillows are traversed by radial fractures infilled by secondary carbonates.
Significance	State. This is one of the few displays of pillow lavas in Victoria and the only recorded pillow lavas in Victoria and the only recorded pillow lava site in Older Volcanic rocks. The presence of the pillows indicates the lava at this point entered a body of water and probably marks the limit of the marine shoreline in the Early Miocene. This is important in determining the Tertiary palaeogeography of the Geelong-Maude area.
Management	Class 1. It is important that any road maintenance or widening operations do not destroy the face in this cutting. Careful engineering evaluation is necessary before any change is made to the section currently exposed. Any management in this regard should be designed to maintain a steep face on the cutting and not develop a covered or otherwise artificially stabilized slope.
References	Bowler, J.M. (1963).Tertiary Stratigraphy and Sedimentation in the Geelong/Maude Area, Victoria. Proc. R. Soc. Vict. 76:69-137.

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