The Rarest Rock in Victoria

#victoria #volcano #geology Discover the rarest volcanic eruption in Victoria’s geological history—one that broke every rule in the book. Unlike the vast basalt plains that define southeastern Australia’s volcanic landscape, this video uncovers a lone hill near Trentham that erupted an extraordinary type of lava known as icelandite. Found nowhere else in the state, this rock is a chemical and tectonic outlier, with origins that hint at deep mantle anomalies and ancient crustal interactions. From its unusual silica-rich composition to the explosive, gas-charged eruption that brought it to the surface, Spring Hill holds clues to a forgotten chapter of Australia's volcanic past. This video dives into the geological significance of Spring Hill’s icelandite, a rare intermediate volcanic rock typically found in Icelandic rift zones—not in intraplate basalt provinces like Victoria. Through fresh research, field observations, and recent dating methods, we explore how this singular eruption likely occurred between 8.3 and 5 million years ago, forming blocky lava flows enriched with crustal xenoliths from the Ordovician Castlemaine Group. You’ll learn how a combination of mantle heterogeneity, crustal contamination, and unusual tectonic conditions created the only icelandite eruption known in the region. Whether you're a geology enthusiast, a student of earth sciences, or simply curious about Australia’s volcanic secrets, this video unpacks the science behind a unique lava type and the one place it erupted. It’s a must-watch for anyone interested in the geological history of Victoria, rare volcanic rocks, mantle processes, and the surprising complexity hidden beneath an unassuming hill in central Australia. Studies Used To Construct This Video: Petrographic, geochemical and age characterisation of crustal xenoliths from Coliban Dam, central Victoria, with implications for the early evolution of southeastern Australia, pre Lachlan Orogen: https://figshare.mq.edu.au/articles/thesis/Petrographic_geochemical_and_age_characterisation_of_crustal_xenoliths_from_Coliban_Dam_central_Victoria_with_implications_for_the_early_evolution_of_southeastern_Australia_pre_Lachlan_Orogen/19439024?file=34537451 Multiple felsic events within post-10 Ma volcanism, Southeast Australia: inputs in appraising proposed magmatic models: https://www.tandfonline.com/doi/abs/10.1080/08120099.2014.883640 Thank you so much for watching! If you are not in a position to donate, I totally understand! The biggest supporting factor that you engage in is to watch our videos all the way to the end (very important for helping us rank) and to share them around so please consider doing this so that Youtube recommends our channel more. Check out the OzGeology website: https://ozgeology.com If you are in a position to support our channel on Youtube Membership or by joining our Patreon, the link to all of this can be found below: 🎥 If you would like to support this channel, consider joining our Patreon: https://patreon.com/OzGeology 👉 You can also click the "join" button to join our Youtube channel's membership. Every contribution helps to create more videos. YouTube Membership: https://www.youtube.com/channel/UCxLrvjGBzYmj8W1rJToPasg/join 🌋 Subscribe to our Youtube Channel: https://www.youtube.com/channel/UCxLrvjGBzYmj8W1rJToPasgsub_confirmation=1 💥Link To Our Facebook: https://facebook.com/OzGeology 🌏 About OzGeology The core mission of OzGeology is to make geology exciting, accessible, and inspiring for everyone. Instead of presenting rocks and earth science as dry or overly academic, OzGeology brings stories of the planet to life, revealing how every mountain, mineral, and landscape tells part of Earth’s grand adventure. The goal is to help people see the world differently, to understand the dynamic forces shaping Australia and beyond, and to spark curiosity in the next generation of geologists. Through engaging storytelling, field exploration, and clear explanations, OzGeology turns the study of our planet into a journey of discovery rather than a classroom lecture.