Site 6 Creek Parade, Northcote/Collingwood - Basalt Columns and Lava Cave

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 5000/04.07 E23550 N 15880 to E23800 N16000
	Right bank valley side of the Merri Creek opposite Ross Street and Creek Parade, Northcote (although the site lies in the City of Collingwood), between Coulson Reserve and the Knott Reserve, Clifton Hill. The site extends for 300 m along the right band east of the low crossing of the Merri Creek by the Merri Path.
Access:	Merri Path and Ross Street, Northcote.
Ownership & Municipality:	Public Land, City of Collingwood.
Site Description:	The principal feature is a very clear exposure of at least two lava flows or flow units that form a vertical cliff face adjacent to the low level crossing of the Merri Creek by the Merri Path at the west of Creek Parade. The lowermost sections of the flows exposed are at creek level 30 m east of the low bridge on the Merri Path. This flow is ropy with many large aligned vesicles and probably represents a thin cooling flow unit (or several units) with rapid gas escape forming aligned and elongated gas bubble holes. The flow is well exposed as it is frequently washed clean of weathered debris by floods in the Merri Creek. Overlying this and well exposed adjacent to the bridge is a massive non-ropy lava flow with complex jointing and weathering features. The lower 3 metres of the flow has persistent vertical joints with a spacing of 40 cm to 50 cm giving a distinct columnar form. Closely spaced but irregular horizontal joints divide the columns into angular sub-blocks. Overlying the columnar section with a disjunct boundary, the upper part of the flow has disorganised jointing giving an irregular fractured surface. The weathering patterns on the lower, columnar flow are unusual in that an irregular spheroidal patter has developed. There are some typical corestones surrounded by “onion skin” layers but in places this weathered fringe is again surrounded by basalt that is apparently little weathered. Further east along the valley slope is a small cave in vesicular and ropy basalt. This appears to be a primary feature of the lava flow (a small lava tube) and is not a weather or erosion hollow.
Significance Rating:	Regional
	This is an outstanding site with very high regional significance. Because of the easy and safe access and the proximity of sites with complementary features, this site could form part of a complex in the Merri Creek gorge at Northcote that could be regarded as of STATE significance. The broader site is significant for the variety of lava structures that are shown in close proximity and with safe access. Despite the widespread occurrence of Newer Volcanics basalt in Victoria, many are on private land or in road cuttings or river cliffs that are not safely accessible. The Merri Creek sites are one of the few safely accessible and clearly displayed sites of complex jointing on Public Land. The weathering patterns and the lava cave are also unusual features.
Site Sensitivity:	Class 2.
	This is a robust site but could be damaged by rock collection. Some sprayed graffiti has recently appeared on part of the outcrop. Both these damaging practises should be discouraged. Overgrowing by vegetation could obscure the outcrops. Priority should be given to the geological qualities of the site, and vegetation that obscures part of the outcrop should be removed. The site has great potential as a geological education site and could be linked with an interpretive study of basalt structures in the Merri Creek gorge.
References:	None Known.

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