To the untrained eye, a pair of beaches on the New South Wales South Coast are simply beautiful spots with crystal clear water and bright yellow sand.
But scientists from all around the world travel to Murramarang National Park for the story the rocks tell, according to geologist and president of Ulladulla's Gondwana Coast Fossil Walk Phil Smart.
When he looks at the rocks on Dark Beach and Myrtle Beach, he sees a sequence of geological events spanning more than 150 million years.
"For what it is, there's nothing that's any better anywhere else in the world," Mr Smart said.
The beaches are two of the world's best examples of what geologists call an angular unconformity — a geological boundary between two rocks from different time periods.
At Dark and Myrtle Beaches, the iconic 300-million-year-old sandstone cliffs of the Sydney Basin lie atop a dark slaty rock 450 million years old.
Mr Smart knows nowhere else in Australia with such a dramatic age difference between two rocks side by side.
'So very different'
About 450 million years ago at the site of the two beaches, mud on the sea floor was metamorphosed into slate.
The ancient slate was eroded down over millions of years before the sea flooded the region about 299 million years ago, bringing with it sand and sediment.
With time and pressure, the layer of sandstone that would become known as the Sydney Basin was forged on top of the old rock, stretching from Newcastle in the north, to Gunnedah in the west and Dark Beach and Myrtle Beach in the south.
The end of the sandstone layer is evident at Dark and Myrtle beaches.
"The rocks are so very different — metamorphic rocks dipping down, sedimentary rocks horizontal," Mr Smart said.
"It's pretty clear cut."
He said the site was significant because of the absence of 150 million years in the rock record, which eroded away before the sandstone layer was laid.
"There aren't too many places in Australia where you can see evidence of a hiatus between one set of rocks — it's rare," Mr Smart said.
"It's pretty impressive we can get that whole story just from looking at those rocks."
Walking through history
Most visitors to Murramarang National Park do not realise what a geologically rich area they are walking through, according to senior visitor programs officer with NSW National Parks and Wildlife Services David Duffy.
"If you don't have the eyes to see it, you completely miss it," Mr Duffy said.
"Every stone has a story — where it has come from, what it has done, how it has formed and where it's sitting today.
"So instead of just seeing a beach and a bit of sand, what I'm seeing is these geological processes over millions and millions of years.
"Every single day those processes are taking place as we watch the tide go in and go out.
"The earth is so rich with all this information, just if only we could see it."
Mr Duffy has noticed a trend of geologists undertaking the new Murramarang South Coast Walk since it opened in 2023.
Many have studied the National Park without ever visiting.
"It's one thing to learn the story on paper — it's another to see it in real life," Mr Duffy recalled a geologist telling him.
Mr Duffy delights in sharing the story of the rocks with others and hopes people can appreciate the sheer beauty of the dynamic environments surrounding them.
"It's beautiful," he said.
"The different layers of sandstone, different rates of erosion, the textures, the colours — it's a beautiful thing to see."