07/03/2026
Sydney founded on Sandstone
Sandstone is a sedimentary rock that dominates Sydney.
In fact, sandstone forms more than half of the Sydney Basin’s sedimentary sequence and was the building material of choice for Sydney’s grand older buildings.
Look no further than the QVB Building, Sydney Town Hall, the Quadrangle at Sydney University and St Mary’s Cathedral to see how Sydney’s early architectural soul is bonded to sandstone.
You can’t help but see it if you visit a Sydney beach or a national park in Sydney and its surrounds.
The varied white, grey, tan, orange, yellow and red colours in this rock are striking and the shapes it forms can be exceptional.
The Royal Coastal Track in the Royal National Park, south of Sydney, provides some great opportunities to observe sandstone whether it be in the cliffs, headlands, rock platforms or random boulders.
The magnificent valleys in the Blue Mountains World Heritage Area are the result of uplift and erosion of sandstone.
Sydney Nimble Tours showcases remarkable sandstone formations in our Sydney private day tours to the Royal National Park and Blue Mountains - giving visitors a deeper appreciation of the geology that shaped Sydney and surrounds.
Formation
Sandstone is generally formed over long periods of time (thousands and millions of years) when grains of sand are compacted.
Common sand grains include quartz, feldspar and lithic fragments (fragments of other rocks that have been broken down over time).
A compaction process occurs due to the weight of layers of water and overlaying sediment.
The compaction is followed by cementation, a process that most commonly occurs when mineral rich groundwater seeps through the sand grains.
The minerals (examples include silica, calcite, iron oxides and clay minerals) act as a glue binding the sand grains together.
Sydney’s sandstone was formed in the early to mid Triassic Period (estimated to be between 235 to 251 million years ago) when the land on which Sydney and surrounds exists was part of the supercontinent, Gondwana.
Types of sandstone in and around Sydney
The predominant sandstone in Sydney and surrounds is Hawkesbury Sandstone. It is a quartz rich sandstone that forms much of the bedrock for Sydney.
An older sequence of sandstone is the Narrabeen Group which lies beneath the Hawkesbury sandstone. It can be seen at the northern beaches, Blue Mountains and Otford.
Shapes
Vertical stress and erosion are key factors in sculpting sandstone into dramatic features such as arches and pillars.
Shapes may be seen in sandstone if you have a creative imagination.
Pareidolia is a phenomenon in which humans perceive faces, animals or objects when looking at things such as rock formations or clouds.
Wedding Cake, Eagle Rock and Boars Head (Megalong Valley, Blue Mountains) are outstanding examples.
Experiencing Sydney sandstone
One of the best places to experience sandstone formations is the Royal National Park.
Both Eagle Rock and Wedding Cake Rock can be seen by hiking on the Royal Coastal Track.
Earthy sandstone colours can be seen in the Blue Mountains when viewing the Jamison, Megalong and Grose Valleys.
Extraordinary sandstone cave formations can also be found in Blue Mountains.
A few of our favourite sandstone caves include the cave underneath Lincoln Rock, the Fortress Ridge track cave and the wind eroded cave near the Grose Valley.
We hope you enjoy the photos of sandstone below as much as we do.
