Mt Hamilton

This information has been obtained from the report: Eruption Points of the Newer Volcanic Province of Victoria by Neville Rosengren. This report was published in 1994 and was prepared for the National Trust of Australia (Victoria) and the Geological Society of Australia (Victorian Division). The review of eruption points was based on an earlier unpublished manuscript Catalogue of the post-Miocene volcanoes of Victoria compiled by O P Singleton and E B Joyce (Geology Department, University of Melbourne 1970).

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 value. 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:	37 47 00S 142 59 00E (external link); 7422-2-N (Woorndoo North) 750160. 16 km SE of Lake Bolac. Woolsthorpe-Streatham Road.
	Mortlake
Land Tenure/Use:	Private land. Grazing, bare, outcrop.
Type 1:	Lava cone with crater.
	Mount Hamilton is a broad symmetrical lava cone surrounded by a lava field. At the summit is a crater 350 m in diameter and almost 40 m deep. The rim of the crater is entire and the base is swampy. The outer walls of the crater have gentle slopes that grade into the surrounding lava flows. The lava flows retain stony rise surfaces and other original features. Of major importance is a group of three lava caves on the southern slopes of the cone with almost 1 km of accessible passages. The caves have branching passages, an unusual feature in lava caves, and one has a considerable amount of sediment on the floor. Several tunnels here display a variety of lava cooling and flow features.
	317 m; 75 m.
National:	This is the best example in Victoria of a lava cone with a deep, enclosed and well-preserved crater and is one of the best examples in Australia of a Tertiary basalt volcano with little pyroclastic eruption and extensive and obvious lava flows. The lava caves are among the largest in Australia and are excellent examples of these features.
Class 2:	The feature is robust and well-preserved but is not accessible or visible to the public. Quarrying, stone removal or other physical disturbance to the inner and outer crater slopes would degrade the site. The entrances to the lava caves are small and could be blocked and damaged by earthworks or other surface disturbance. Recreational caving has degraded many of the decorative features of the caves and mineral specimens have been stolen.
References:	Ollier, C.D. 1963. The Mount Hamilton lava caves. Victorian Naturalist 79, pp. 331-336. Mill, L., White, S. & Mackey, P. (eds) 1980. Victorian caves and karst. Guidebook for 13th ASF Conference, Melbourne 1980. King, R.L. 1990. Geological features of on the Ballarat 1:250 000 sheet. Geological Survey of Victoria Unpublished Report 1990/8.

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