What are the Hamelin Pool stromatolites of Shark Bay?

Stromatolites provide evidence of life on earth from 3.5 billion years ago. At Shark Bay in Western Australia, the Hamelin Pool stromatolites are more accessible than anywhere else.

Why is Shark Bay on the World Heritage List?

Shark Bay in Western Australia is on the UNESCO World Heritage List for the stromatolites at Hamelin Pool. Go to see them, and they just look like rocks. But the stromatolites of Shark Bay are much more important than that.

Hamelin Pool is a 694km drive from the Western Australian capital on the Perth to Broome West Coast road trip. This journey is a good choice for second-time visitors to Australia, and you’ll pass nearby on the drive from Monkey Mia to Coral Bay.

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Hamelin Pool stromatolites boardwalk in Shark Bay

The scene from the boardwalk at Hamelin Pool looks kinda pretty. There’s a dreamy end-of-the-worldness to it, with a series of blackened rocks disappearing into the super-salty waters of Shark Bay, which is protected from the Indian Ocean by Dirk Hartog Island.

They’re not rocks, however. They’re stromatolites – multi layered colonies of bacteria that all live off each other in one way or another. And without them, we probably wouldn’t be here.

The stromatolites of Shark Bay, Western Australia, from Hamelin Pool — The stromatolites of Shark Bay, Western Australia can be observed from the boardwalk at Hamelin Pool.

History of stromatolites

Around 3.5 billion years ago, the only forms of life on earth were extremely basic single cell organisms. Around that time, they started to form stromatolites. They evolved as they interacted with each other in what can be seen as microbial mats. The cyanobacteria making up these mats began to produce their own food via photosynthesis. They absorbed carbon from carbon dioxide and released oxygen into the water.

This created iron oxides which coated sediments that eventually turned to rock. The big red rocks of Western Australia’s outback formed this way. But it also started to change the make-up of the earth’s air. There was nothing to eat the cyanobacteria in these stromatolites, so they mushroomed. And greatly increased the proportion of oxygen within the earth’s atmosphere.

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Evolution of cyanobacteria

Between 2,000 and 1,700 million years ago, two forms of cyanobacteria merged into a new type of more complex organism, known as the eukaryote. Its cells were formed of a nucleus surrounded by a membrane – which is pretty much the building block for all life on earth as we know it now. The long slow process to modern life had properly begun.

For an idea of timeframe, consider that dinosaurs were around between 230 million and 65 million years ago, while humans first appeared around 200,000 years ago. Discovering stromatolite fossils would be an extraordinary delve into the past. That there are still living stromatolites that can be walked around on a boardwalk is on another level altogether.

Tick off 9 Australian bucket list experiences

Take Blue Mountains day tour from Sydney – with kangaroo-feeding at a wildlife park, Scenic World tickets and a Parramatta River cruise.
Snorkel or dive on the Great Barrier Reef from Cairns.
Do Australia’s most spectacular drive on a Great Ocean Road day tour from Melbourne.
Drive along the beach on a 4WD day tour of Fraser Island, the world’s biggest sand island.
Have a dune-top barbecue dinner and stargazing session in the shadow of Uluru.
See penguins on Phillip Island – and more native wildlife at the Moonlit Sanctuary – on a day trip from Melbourne.
Go snorkelling, sandboarding and kayaking on Moreton Island from Brisbane.
Meet gloriously cute quokkas on Rottnest Island near Perth with a ferry and bike hire package.
Kayak with dolphins in Byron Bay.

Seeing the Hamelin Pool stromatolites in Shark Bay

Living stromatolites are found in very few places around the world, and by the most accessible cluster is in this lonely corner of Western Australia. It’s a harsh environment, suitable only for extremophiles, where the big beds of sea grass ensure the water is far saltier than normal and the brutal summer heat regularly sends temperatures above 40 degrees Celsius.

This has bought Hamelin Pool’s stromatolites a degree of protection over the years. They thrive because not all that much else does.

Hamelin Pool stromatolites boardwalk

Walking over the top of them may not provide much visual excitement, but the mental stimulation is there. The stroll is not just one into the past, but one so far into ancient history that it goes back to the beginning of life itself. Stromatolites provide the earliest evidence of life on earth. This is why Hamelin Pool is one of Australia’s most important historic sites.

For more historic sites in Western Australia, the Houtman-Abrolhos Islands off the coast of Geraldton were the site of the infamous Batavia shipwreck and mutiny. You can drop by Hamelin Pool on the drive from Geraldton to Carnarvon.