in the Silurian and Devonian periods (446-359mya), the oceans were retreating and half of Victoria was above sea level, and
this period produced Victoria's most explosive volcanoes, the oldest example is Mount Burrowa, in Victoria's north-east. The repeated eruptions were so numerous that in some parts of central Victoria, the volcanic layers are 1km thick. The remains of this peak vulcanic era now form Mount Macedon, the Dandenong Ranges, the mountainous region between Healesville, Warburton and Eildon (including Mount Donna Buang and the Cerberean Ranges) and near Violet Town, in the northern part of the Strathbogie Ranges.
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