The Twelve Apostles, a popular tourist destination along Australia's Great Ocean Road, has been found to be around 8.6 million to 14 million years old.
Geologists have used microscopic fossils embedded in limestone to determine the age of the giant golden pillars.
A/Prof Stephen Gallagher from the University of Melbourne said: 'We see layers, we see time, we see a history of the Earth.'
The rocks were formed during the mid-Miocene era and have been lifted and tilted by tectonic plate movements over millions of years.
Dr Matthew McCurry, curator of palaeontology at the Australian Museum, said: 'Foraminifera fossils were a really useful method for dating rocks and fossils in marine ecosystems.'
The study highlights the importance of precise dating in understanding critical events in the history of our planet.