What is a lava blister?

To be honest, I’d never heard of a lava blister until I traipsed around Williamstown’s point and came across this unusual rock formation.

Lava blister by Port Phillip Bay

While Australia has no active volcanoes, that wasn’t the case millions of years ago. Western Melbourne was a blaze of volcanic activity. In fact, Victoria’s basalt plains form one of the largest lava plains in the world. When lava flowed to the shore of Point Gellibrand, gas built up within the magma causing a bubble measuring three metres in diameter.

Today the curved roof has collapsed, but the circular sides remain. This formation is extremely rare and I was thrilled to catch a glimpse of this unique rock formation.