Why the 12 Apostles Australia Are Disappearing—Geology Explained

The 12 Apostles Australia are so much more than just a magnificent view to admire. These majestic rock formations rising from the Southern Ocean are geological records of the region's past, as well as a glimpse into its future. But did you know that in the past they looked completely different? And that there weren't even 12 towers to begin with?

This post is all about the 12 Apostles Australia. We'll learn how these rock towers were formed, how they ended up looking as they do today, and what the future of the 12 Apostles in Australia looks like. And finally, I'll tell you about a few other Apostles that you didn't even know were there.

What are the 12 Apostles in Australia?

The 12 Apostles, a series of breathtaking limestone stacks emerging from the sea, are a highlight of Victoria's dramatic southwest coastline. Located just off the shore of Port Campbell National Park, the 12 Apostles are about 275 km west of Melbourne and can be reached via the scenic Great Ocean Road.

Rising abruptly from the ocean, and reaching up to 50 meters in height, these majestic rock pillars are clustered together to form a magnificent view, totally worth visiting.

How were the 12 Apostles formed?

Just like all the other geological wonders we talked about, this one also has a history that stretches over millions of years, and it happened in several stages.

12 Apostles Limestone Formation

The cliffs and the Apostles along Victoria’s famous Shipwreck Coast are made up of limestone, a soft, porous rock whose inception goes back to hundreds of millions of years ago, when the entire region was under water. Shells, corals, and skeletons of marine creatures settled at the bottom of the ocean, and over long periods of time, these layers of sediment were compacted and turned into limestone.

This limestone along the Shipwreck Coast was primarily deposited during the Mid-Late Miocene period, about 15 to 20 million years ago.

12 Apostles Erosion Process

The formation of the 12 Apostles began about 15 to 20 million years ago during the Mid-Late Miocene period. The action of powerful winds and waves crushing into the coast began the erosion process, which eventually led to the creation of the 12 Apostles. The erosion process also happened in several stages.

Cave Formation

In the first stages of erosion, the erosion started creating small cracks and sea caves, especially in the lower layers, where the rock was weakest. Those layers were made up of softer mudstone and clay, which erode faster.

Arch Formation

During the next stages of erosion, some of these caves grew deeper and deeper and eventually connecting to one another, to create a series of arches along the cliff face.

Stack Formation

But the relentless forces of nature didn't stop at the arches. They continued their action on the arches until they gave in and collapsed, leaving behind a breathtaking landscape of tall, isolated limestone pillars standing majestically in the ocean. And it is these rock formations that we call the 12 Apostles.

But there are not 12 rock pillars. So then why do we call them the 12 Apostles?

Origins of the name Twelve Apostles

The Twelve Apostles was actually not the original name of these rock formations. Up until 1922, this site was known as the Sow and Piglets, with Muttonbird Island being the Sow, and the smaller rock formations being the piglets.

While known under various other names, including the Pinnacle, Razorback, Island Archway, Thunder Cave, Bakers Oven Rock, Sentinel Rocks, and the Grotto, the name by which is most commonly known today is the 12 Apostles. The site received this name purely for tourism reasons.

There are not even 12 of rock formations. At the time of the renaming, there were 9 of them. However, as erosion never stops working, on 3rd of July 2005, one of them collapsed, leaving only 8 Apostles standing above the ocean waves. And I say above the waves because there are a few other Apostles hidden by the waves. And these are the Drowned Apostles.

The Future of the 12 Apostles Australia

There were 9 Apostles and not there are only 8. Due to the relentless coastal erosion, these towering limestone stacks are slowly but surely crumbling at a rate of about two centimeters per year, a process of erosion that is wearing away the rock bit by bit.

But do not worry, we don't have to say goodbye to the Apostles just yet. It will still take time until the 8 remaining Apostles will collapse, and even when they do, new ones will form to take their place. So whenever you go to visit the Apostles, you are guaranteed a captivating view.

Just as the winds and waves eroded the cost in the past to create the current Apostles, they continue to erode the cliffs, creating new caves, then arches, and eventually a new set of Apostles. According to geologists, the full transformation from cliff to cave to arch and then to stack can take anywhere between 800 and 1800 years—a testament to nature's remarkable patience in creating its stunning masterpieces. So while the current Apostles are temporary, this ever-evolving coastline ensures their legacy will live on!

The Drowned Apostles

The Drowned Apostles are a series of five limestone stacks submerged in the ocean, about 6 kilometers offshore from the Twelve Apostles. In contrast to the much taller 12 Apostles, measuring between 30 and 67 meters, the Drowned Apostles stand at a much more modest height, reaching only 7 meters.

Similar to their iconic cousins above-ground, these the Drowned Apostles were most likely formed through the slow and gradual process of erosion over millions of years. However, unlike their cousins, these ones didn't have the time to erode away as they were swallowed by the sea during the last ice age, around 20,000 years ago. When the ice sheets melted, it caused the sea levels to rise dramatically and drown the limestone towers, flattening their tops in the process.

The drowned apostles were likely formed by the same processes as the present-day Twelve Apostles, though around 60,000 years earlier. If they hadn't been submerged so quickly, these stacks would likely have ended up on a similar path of erosion and collapse as the 12 Apostles.

The discovery of the drowned apostles enriches the experience of visiting the Twelve Apostles, allowing visitors to imagine what the coastline looked like in the distant past.

Have you ever been to the 12 Apostles or any other similar formation in the world? What was your experience like?