The gently rounded shapes of “the mount” give little hint today of the explosive violence of its past.
Aboriginal legends tell of “mountains of fire” when spectacular volcanoes threw out fountains of scoria froth and occasional large blocks of solid lava or “bombs”.
If the exploding magma encountered water near the surface, the explosion was particularly dramatic!
The water became super-heated, creating a huge head of steam, which blasted the magma and surrounding rocks into clouds of fine ash or tuff onto the outer rim of what is known as a maar.
The Mt Leura complex is one of the largest maar and tuff rings in Victoria and is a rare example of a “nested maar.”
After the original broad shallow crater was formed, volcanic activity within it caused the creation of more than twenty scoria cones, of which Mt Leura and Mt Sugarloaf are the largest.
Today, from the summit of Mt Leura, the wider rim can be seen in the distance, encircling the “nested” cones.
Although the vast volcanic plain, known as the Victorian Western Volcanic Plains was formed 2 − 4.5 million years ago, the Leura maar was formed only 10,000 − 40,000 years ago and is considered dormant rather than active (or extinct)!
Below see maps of crater lakes Bullen Merri & Lake Gnotuk: