What is the name of the limestone stack formation along the Great Ocean Road?

The limestone stack formation along the Great Ocean Road is the Twelve Apostles. These towering sea stacks stand just offshore in Port Campbell National Park, on Victoria’s dramatic southern coastline.

The stacks formed from Port Campbell Limestone deposited roughly 15 to 5 million years ago. Southern Ocean waves gradually cut caves into the cliffs; the caves became arches, and collapsed arches left isolated pillars of rock. Continued erosion is still reshaping the coastline.

Despite the name, the formation has not had twelve surviving stacks in modern times. It was originally associated with names such as the Pinnacles and the Sow and Pigs, and “Twelve Apostles” was promoted as a more memorable name for tourists. Several stacks have since collapsed, including one in 2005 and another in 2009.

The Razorback, The Arch, and London Bridge are separate formations in the same broader coastal landscape. They are nearby attractions, but they are not the collective formation identified by this question.