Associate Professor of Geology at Otago University James Scott thought Pourerere Beach could have more such rock types than the more well known Moeraki boulders. Photo / Tracy Gay
Associate Professor of Geology at Otago University James Scott thought Pourerere Beach could have more such rock types than the more well known Moeraki boulders. Photo / Tracy Gay
A recent storm has uncovered a series of boulders along Pourerere beach which could rival the famous Moeraki attraction.
The unusually spherical boulders were spotted by Pourerere resident Tracy Gay over the weekend.
"They come and go," she said.
"I haven't seen them for a few years."
However, large swellsduring last week's polar blast helped reveal the unusual looking rock formations.
She said they reminded her of the Moeraki Boulders on Koekohe Beach, Otago.
Those were formed from calcite concretions about 65 million years ago and exposed by coastal erosion.
Geoscience Society president and Associate Professor of Geology at Otago University James Scott explained the rocks were the result of concretions in sedimentary rocks.
"They might look like giant cannonballs or something that has been rolling around on the sea floor, but they will be made of a type of mudstone.
Associate Professor of Geology at Otago University James Scott explained the boulders are uncovered as softer material around them erodes. Photo / Tracy Gay
"There will be something in that which forms an attraction point and it starts to accumulate and carbonate.
"It could have been a bone or a leaf."
He estimated they were formed underwater between 25 to 70 millions years ago, before being lifted up to the surface by tectonic processes and then being uncovered as softer material around them eroded.
"We are talking about rocks that are millions of years old."
Scott said previous concretions had even resulted in the discovery of several fossils, including a plesiosaur - a marine type of dinosaur - found near Shag Point, Otago, in 2002.
Significant swells which hit the east coast last week have helped uncover a series of uniquely spherical boulders along Pourerere Beach. Photo / Tracy Gay
He said while these types of formations are "pretty uncommon", they can occur anywhere.
"Moeraki is a particularly striking example.
"It looks like there are more exposed at Pourerere than there are at Moeraki."
If they were more regularly visible, he thought they could be a strong contender for the tourist attraction - high praise from a self-described South Islander.
"You wouldn't get them to yourself, that's for sure," he said.
