Until now, scientists had only a limited understanding of how the Twelve Apostles developed into the landmark seen today.

A Natural Record of Ancient Climate and Sea Levels

Associate Professor Stephen Gallagher, the study's lead researcher from the University of Melbourne's School of Geography, Earth and Atmospheric Sciences, said this tectonic activity turned the Apostles into one of the most complete and accessible records of past environmental conditions.

"Much like an environmental time capsule, each layer of these giant structures preserved information about the Earth's climate, tectonic activity, plants and animals over millions of years, including a key time about 13.8 million years ago when the climate was much warmer than what it is today," Associate Professor Gallagher explained.

He added, "We are using this 'window back in time' to understand where temperatures and sea levels may be heading on our current path of climate change. With only eight of the twelve Apostles remaining, we need to study and learn from them while we can."

New Evidence Reveals Younger Age

The rock layers, similar to tree rings, have allowed scientists to estimate the age of the formations with greater precision than before. The results suggest the Apostles are younger than earlier research indicated.

"Early preliminary research indicated the ancient limestone layers ranged between seven to fifteen million years old, but we discovered microscopic fossils that more accurately dated the layers as 8.6 to 14 million years old," Associate Professor Gallagher said.

The study was published in the Australian Journal of Earth Sciences.

From Ocean Floor to Coastal Landmarks

The research shows that while tectonic forces slowly pushed the rock layers upward over millions of years, the dramatic pillars visible today formed much more recently. After the last Ice Age, rising seas and coastal erosion carved and exposed the towering structures along the shoreline.

Tilted Layers Reveal Ancient Earthquakes

The team also found that the uplift was not uniform. Instead of rising evenly, the rock layers were bent and fractured during the process.

"We also uncovered that the tectonic movements didn't push up the Apostles perfectly straight. Instead, they forced layers to tilt and break along the way. If you look closely at the cliffs around the Twelve Apostles today, you can see the limestone layers are not flat but are, in fact, tilted by a few degrees. Small fault lines can also be seen, which are records of ancient earthquakes," Associate Professor Gallagher said.

Ongoing Research Into Past and Future Changes

Scientists are now studying individual layers in greater detail to reconstruct past climates, ocean conditions and sea levels. This work could help explain how ancient geological processes continue to shape modern coastlines and influence ongoing erosion.