Located an hour’s drive from the city of Dunedin in New Zealand’s South Island, Folden Maar has become one of the world’s most significant but troubled fossil sites. This shallow volcanic crater lake (called a maar) was formed by a powerful eruption 23 million years ago – the beginning of the Miocene epoch, when the climate in this part of the world was much warmer and wetter than it is now.
A tropical forest grew around the lake for at least 120,000 years. in its waters tiny unicellular algae called diatoms flourished every spring and summer, and then died and sank to the bottom. “Diatoms are in some ways the most important fossils because without them we wouldn’t be able to preserve other things,” says Daphne Lee, a geologist at the University of Otago in New Zealand who has led scientific excavations at Foulden Maar for nearly two decades.
And these other fossils of plants and animals are sensational. Lee and her colleagues unearthed an entire ecosystem perfectly preserved in the powdered diatomaceous earth: spiders, dragonflies, fruit, flowers with pollen grains on their petals, fish with jagged scales, the complex wings of termites, the hexagonal latticework of complex fly eyes, and iridescent beetles that still sparkle green, copper and bronze.
Most often, they found leaves—so delicately compressed that climatologists could analyze their structure and chemical composition to discover that atmospheric carbon dioxide reached 550 parts per million in the early Miocene, levels similar to those predicted for Earth by 2050.
Li and her colleagues published scientific papers about their findings, but they did not talk about the site more widely. “Because we tried to maintain good relations with the mining companies [that owned the land]of which there were several, we didn’t give the site the public recognition it deserved,” she says.
But in 2019, when a leaked document revealed that the last company to own the mine, Plaman Resources, planned to mine the entire site and export the diatomaceous earth as animal feed, Lee was spurred into action. She began speaking to the media, local authorities and the public at meetings about Foulden Maar. Together with paleontologist Uwe Kaulfuss and paleobotanist John Conran, she began work on the book. Fossil treasures of Folden Maar: a window into Miocene Zealand, published in New Zealand this week Otago University Press and available in the US this December, is an illustrated guide to the site’s history, science, and fossil discoveries. “I thought, ‘Well, if we’re getting to the point where this whole site could be destroyed, we really have to get this story out there,'” Lee says.
Although public pressure played a role in Plaman Resources abandons mining plans, and the company became insolvent later in 2019, Foulden Maar still has no formal protection. Dunedin City Council, which says it hopes to buy the site and preserve it for science, has been in talks for three years with a company appointed to manage Plaman’s business affairs, called the trustee. Neither side would comment to Scientific American on the progress of those discussions. And in a suspended state, scientists are prohibited from visiting the site.
Scientific American spoke with Lee about the fossil treasures of Foulden Maar, what they reveal about our planet’s past and her hopes for the future of the place.
[An edited transcript of the interview follows.]
The book tells the story of this place. Why is this so important?
First, it is the most amazing fossil preservation. It is one of the few places in the world where Lagerstätt is preserved. It’s a word used for real fossil troves where there are even soft fossil parts—things like eyes, skin, flowers with petals and pollen, things that are almost never preserved in other situations. Foulden provides a snapshot of biodiversity found nowhere else on the planet.
Another feature of Folden is that we have two ecosystems preserved. It was a very small lake, maybe a couple of hundred meters deep and a kilometer across. But because of the way the diatomite accumulated at the bottom, everything that lived in the lake and fell to the bottom is pickled [preserved in liquid] there.
And not only that, the rainforest ecosystem around the lake has also been preserved: every leaf, every blown flower, every insect. It is with this high resolution that we have this year after year record. It’s because it was a closed system, it was small and deep that you get that kind of conservation.
It’s very, very unusual to have such a combination of factors come together in one place, and it means we can create a really detailed and accurate picture – just go back in time, take a walk in the forest and take a dip in the lake.
Tell me about some of the impressive fossils that have been found at this site over the years. There were orchids, bird droppings, dragonflies, ants. What else was discovered?
There were fish swimming around in the lake, and there seemed to be a lot of eels. My colleague Uwe Kaulfus found the first one. He thought, “That’s a very long, funny fish,” so he went back to the pile the digger pulled out and searched for days until he found other pieces that matched it, and then put them back. together, like a puzzle. It was the only freshwater eel fossil from the southern hemisphere until we found more. It really changed our understanding of freshwater eels around the world.
And you mentioned that you found one particularly wonderful fish.
This was my best fossil find. Diatomite is really amazing stuff – you can cut it with a pocket knife, shovel or chainsaw. A colleague of mine developed a technique for cutting the blocks with his chainsaw, and then we all sat around with field pocket knives and split them. I once split a block and it just happened to split that particular fish in half as if it were a fillet.
You can count his spine; you see these really tiny bones as thick as your hair. And you can see that it is very different from any other fish. We named him Galaxias effususwhich means it’s kind of luxurious, better than any of the ones previously described.
I guess you would like to come back and see what else you can find on the site. But you can’t, can you?
We’ve been going every month or so and every time you go you find something new. But when the mining company came under control, the manager said that no one could go there. So, despite many requests to host groups of students, to bring academics from overseas who came to New Zealand to visit Foulden Maar, they were absolutely adamant. The gate is effectively closed. All we can do is look over the fence and feel very disappointed.
You’ve said in the past that your dream for Folden Maar is a sort of geopark or World Heritage Site where children and students can learn about the geology, fossils and climate history of the Earth. Do you think this is something you will see in your lifetime?
I certainly hope so. If it all works out, it would be nice to start regular trips to Foulden Maar so people can see for themselves what the book is about. The best way to explain science is to actually be there.
I like to tell stories and Foulden has so many different stories about the lake, the rainforest, the climate and the volcanic eruption. The fact that the mountains you see in the background weren’t there when the maar formed, that there is snow on the hills now, but it wasn’t there then, sort of brings all these different concepts together in one very small place. only a kilometer or two across.
It is a place of fossil treasures, like a museum full of treasures, and they belong to everyone.