The Ancient Fires of the West

Did you know that Victoria was once a teeming site of intense volcanic activity? That’s right! Over many millions of years across a number of epochs, the Western Region of Melbourne was one of the continent’s most geologically active areas, with much of its topography having been formed from sustained lava flows.

Known variously as the Victorian Volcanic Plains or the Newer Volcanic Province, the Western Region is part of the third largest volcanic plains in the world, covering over 10% of the State of Victoria or 2.3 million hectares.

Although much of the geological material was formed between 2.5 to 5 million years ago, substantial portions or deposits date as far back as the beginning of the Cenozoic era (‘New Life’) some 65 million years ago. Some of the volcanic rises that shaped the land included Mt. Kororoit and Mt. Bullengarook, as well as Mt. Cottrell not far from Tarneit.

While Bullengarook is a higher, steeper volcanic site, Mt. Cottrell - especially when viewed from the You Yangs - is the most massive basalt cone of the Werribee Plains volcanoes. Huge rivers of lava once flowed from its 205m summit, and may in fact have shaped the course of the Werribee River. The average depth of the lava upon the plains has been recorded at about 60m, built up over many small flows.

Over 400 volcanic sites have been identified on the plains, and it is generally accepted that indigenous people would have likely borne witness to some of the eruptions, as evinced in their stories of rocks and fires spewing from some of the mountains. Further evidence to support this has been the discovery of stone tools buried in volcanic ash near Warrnambool.

Much of this geological history can be seen in the exposed rock faces of Werribee Gorge and the K Road Cliffs, as well as in the remnant presence of sites such Mount Cottrell. And of course, it is in the very soil, which was identified by European settlers as ideal for their crop growing activities and led in part to the West becoming known as the food bowl it is today.

It really does go to show just how much history is at your feet, in and around Tarneit. So strike out and explore your region today – you never know what you’ll find in those hills!