Victoria’s young volcanoes

Volcanoes have been active in shaping Victoria’s geology for the past 600 million years. The youngest period of volcanic activity began around 5 million years ago and is concentrated in the western half of the State, with an extension into southeastern South Australia. Geologists refer to this region as the Newer Volcanic Province (NVP) and subdivide it within Victoria into the Central Highlands and Western Plains subprovinces. Overall, the NVP contains over 400 recognised eruption centres, including lava shields, scoria cones and maar craters, along with combinations of all three types. While generally termed ‘basalt’, the lava flows show a range in their chemical compositions. Available age determinations show that volcanic activity has occurred intermittently since about 4.6 million years ago to around 5000 years ago (Mt Gambier in South Australia), however only around 25 eruption centres have been accurately dated using modern techniques.

The NVP is one of around a dozen similar volcanic regions distributed all along the eastern Australian continental margin. This style of activity is referred to as intraplate volcanism, because it occurs in the middle of a tectonic plate, well away from the edges where the Earth’s biggest and most active volcanoes are situated.

The talk will illustrate the main types of volcanoes in the NVP, briefly touch on how they are dated, endeavour to explain why they are there, and offer some predictions on when the next eruption might occur.

Dr Bill Birch is Curator Emeritus at Museum Victoria, after a 40-year career as Senior Curator in geosciences, with responsibilities for building the mineral, rock and meteorite collections. He has wide interests in the geological features and mineral occurrences of Victoria, and has published over 200 papers and articles on his research interests. He has also travelled widely, collecting geological specimens in Greenland, Siberia, northern Pakistan, Canada, South Africa and St Helena. He has also been actively involved in professional geological and mineralogical organisations in Australia and overseas. His contributions to the Earth Sciences have been recognised through the awarding of the Selwyn Medal in 1999 and an Order of Australia (AM) in 2006. He served as president of the Royal Society of Victoria between 2013 and 2016.

This luncheon will take place at the Savage Club at 12 noon for 12.30pm. The Club is at 12 Bank Place (off Collins Street) in the City. Cost is $55 including drinks. All guests are most welcome; the more the better. Would you please advise Peter Baines at lunches@cambridgesociety.org.au or on 9820 2334 by latest Monday noon, 18 June, if you will be coming (and dietary requirements). Those emailing their intention to attend should ring Peter to confirm if they receive no email confirmation from him within 24 hours of booking.