The District's Volcanoes
Sunshine and the surrounding district are located on the eastern end of the Victorian Volcanic Plains that stretches from the South Australia boarder to Melbourne in a 100km wide belt. This makes the Victorian Volcanic Plains the third largest volcanic basaltic lava plain in the world.
Much of Victoria’s volcanic deposits are approximately 65 million years old with the most recent eruption estimated to be only 5,000 years ago. This means that the indigenous people of Victoria would have witness some of these eruptions.
Closer to Sunshine and the surrounding district there are 20 known extinct or what some scientists believe are only dormant volcanoes. Many of these volcanoes are located on the Western side of the district in an arc from the North to South - West.
Some of the more well known volcanoes in the district include;
Aitken Hill (Mt Yuroke) (Just west of Greenvale, 3.5km south east of Craigieburn)
Mt Macedon (2.3km north - west of the township of Mt Macedon)
Mt Holden (2 km west of Sunbury)
Bald Hill (3 km SW for Sunbury)
The Heights (Sunbury) (1.5 km south of Sunbury)
Redstone Hill (3 km south of Sunbury)
Mt Kororoit (5 kms South West of Diggers Rest)
Spring Hill (11km south of Bacchus Marsh)
Mt Cottrell (2.6 km east of Eynesbury on the Werribee plains)
Greek Hill (5.5km west of Tarneit, north of Dohertys Road)
Cowie Hill (2km north west of Tarneit, near Tarneit Rd)
Two district lava flows exist, one from the Oligocene age (34 million years ago) and one from the Pliocene and Pleistocene era (11,500 to 2.5 million years ago)
In some areas these lava fields are 60 – 80 metre thick with the underlying bedrock being Silurian marine claystone, siltstone and sandstone from 300 to 400 million years ago.
Examples of these layer of rock formations can be seen in Brimbank Park, Taylors Creek, and the Organ Pipes National Park.
The Aborigines depended on this basalt stone for making implements for grinding seed, crumbling, cutting wood, damming waterways for fishing, etc.
As the lava is quite close to the surface, thus providing easy access to the rock, it didn’t take long for the white settlers to find uses for the basalt “Blue Stone” including dry stone walls, buildings, road, bridge & railway line construction, etc.
The lava fields from these volcanoes are also the reason why the different vegetation is on the east side of Melbourne compared to the west side.
Ref: Friends of Lower Kororoit Creek (FOLKC)