Castle Rock on the Surf Coast
Castle Rock is an ancient Limestone stack that sits out of the water just off the coast on the cliffs below Split Point Lighthouse.
It’s made of sedimentary rock that formed millions of years ago at the bottom of the ocean, like most of the coastline along the Great Ocean Road.
Around 20 millions years ago, this whole coastline was underwater. Plants and fish that died and sunk to the bottom of the ocean, alongside other debris compacted over millions of years and formed the Sandstone. The area also has a lot of Limestone, which pretty much means it has more chalk and fossils than the average sedimentary rock.
The current level of the ocean was reached about 6,000 years ago after the Ice Age. The water and wind has been eroding the stone at a rate of about 1.5-2cms per year, ever since.
In the future, this part of the coast might have bunch more stacks like the 12 Apostles or an arch like the London Bridge. To see more of what the erosion can create out of the sandstone cliffs, head down to the Port Campbell National Park which is about 150 kms further to the west on the Great Ocean Road.
There’s also a Castle Rock at the 12 Apostles.
Getting down & around to Castle Rock
When you drive into Aireys Inlet, you’ll see the Aireys Pub on your right. A few hundred metres after the pub, turn left and follow the signs to Split Point Lighthouse.
Only 5-600 metres from the Great Ocean Road, you’ll get to the lighthouse car park, park here.
Only a couple of hundred metres to the the north-east of the lighthouse/back towards Melbourne, there’s a path that goes along the cliff edge and you’ll be able to get a view of Castle Rock. To get up and close, take the set of stairs down the 40-50 metre cliff to Step Beach. Once you make it to the beach and if the tides out, you’ll be able to walk to the right and get over to the rock with ease.
Keep in mind that Castle Rock can be a bit dangerous and hard to get to in rough weather or if the tide’s in, but it’s normally pretty easy.