Volcanic variety
There are several ways volcanoes have been formed in the Newer Volcanics Province, but many sites display elements of more than one type.
1 Ash cone Similar to a maar but with steeper sides and a crater sitting above ground level. The only ones in the NVP are a cluster of five at Mt Burr, north-west of Mt Gambier Range.
2 Scoria cone These eruptions were violent, shooting out very hot, bubbly lava, which cooled on descent into small stones called scoria. They would heap around the eruption point to form a cone. A breached cone is where lava breaks through the crater wall, e.g. Mt Elephant.
3 Lava shield The lava that comes up through a ground vent is quite runny and streams away to form low hills with gently sloping sides. They’re the most common volcano in the NVP and a good example is Mt Pierrepoint near Hamilton.
4 Maar crater Rising hot magma encounters groundwater, creating high-pressure steam to shatter the magma and rocks into ash, which falls to form a shallow crater. The best example is Lake Purrumbete.
5 Complex volcano Has characteristics of more than one eruption type, such as Tower Hill, which has scoria cones nested in a maar lake.