If you’re planning to walk Victoria’s Great Ocean Walk, this is worth knowing.
Microscopic fossils trapped in limestone have helped geologists pinpoint the age of the Twelve Apostles at between 8.6 and 14 million years old.
The famous cluster of towering sea stacks draws around 2.8 million visitors each year and stands as one of the most iconic sights along the Great Ocean Road in south-west Victoria.
While most visitors see only dramatic rocks rising from the Southern Ocean, scientists read the landscape as a detailed record of deep time. Associate Professor Stephen Gallagher of the University of Melbourne explains: “We see layers, we see time, we see a history of the Earth.”
Over millions of years, shifting tectonic plates gradually lifted and tilted the region’s geology, exposing the underlying Gellibrand Marl, which dates back around 15 million years, along with the younger Port Campbell limestone formed during the mid-Miocene period. These layers are now capped with more recent red-brown Hesse clay.
The movement of the Earth’s crust did not raise the formations evenly. Instead, it fractured and tilted the rock layers, leaving them visibly slanted today. Along the surrounding cliffs, careful observation reveals angled limestone beds and small fault lines — evidence of ancient seismic activity.
The Great Ocean Walk itself is one of Australia’s most rewarding coastal hikes, stretching around 110 kilometres from Apollo Bay. It moves through eucalyptus forest, coastal heath and remote beaches, offering constantly changing scenery and abundant wildlife.
Typically completed over six to eight days, the trail is well supported with campsites and day-walk sections. It builds gradually in impact and scenery before reaching its dramatic finale at the Twelve Apostles — a fitting end point where geology, time and landscape come together in one unforgettable view.