4-10 Interface between Condah Swamp sediments and Harman Valley lava flow at Wallacedale

This information has been developed from the publications:

An assessment of the Geological/Geomorphological Significance of Private Land in the Shire of Portland (1981) by N. Rosengren, J Mallen, T Shepherd.

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 (external link) for details of geological heritage reports, and a bibliography.

Locality:	7222-755008. Four kilometres south-west of Wallacedale.
Access:	Wallacedale-Byaduk Road.
Geology:	Newer Volcanics basalt and Quaternary swamp deposits.
Geomorphology:	The Condah Swamp has formed as a consequence of drainage disruption of the headwater tributaries of Darlot Creek by the Tyrendarra lava flow. The site marks the eastern edge of the Condah Swamp and the western extremity of exposed Harman Valley lava flow. West of this point the Condah Swamp sediments overly the basalt of the Harman Valley flow.
Significance:	State. This site provides evidence concerning the relative ages of the two lava flows and illustrates clearly the impact of the lava on the drainage systems of the area.
Management:	Although the site has been disturbed by drainage of the swamp, the interface between the lava and sediments is clearly seen. Extensive excavations of swamp material east of the road should be prohibited.
Reference:	Ollier, C.D. and Joyce, E.B. (1964). 'Volcanic physiography of the Western Plains of Victoria', Proc. Roy. Soc. Vic. 77 (2) : 357-386.

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