From Sea Floor to Sea Stacks: Unveiling the Twelve Apostles' Formation
New research uses high‑resolution mapping and fossil analysis to pin down the Twelve Apostles’ formation: Miocene seas deposited limestone about 14 to 8.6 million years ago (with the Gellibrand Marl around 14–15 Ma and Port Campbell Limestone forming later), followed by crustal compression and tilting that began around 8.6 Ma. The dramatic sea stacks took their present form in the last 20,000–23,000 years as sea levels rose after the last glaciation, with ongoing erosion causing collapses (one in 2005, another in 2009) and the landscape continuing to evolve as a climate record from the Miocene.
