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  • This article by Dr Nic Rawlence was originally published under the title Proposal to mine fossil-rich site in New Zealand sparks campaign to protect it. Dr Rawlence is a senior lecturer in ancient DNA and co-director of the Otago Palaeogenetics Laboratory at the University of Otago. Dr Rawlence is opposed to the mining of this site. This article has been republished from The Conversation under Creative Commons licence CC BY-ND 4.0.

    Rights: Daphne Lee, CC BY-ND

    Foulden Maar site

    A fossil dig by University of Otago students at Foulden Maar.

    An Australian company’s application to mine a fossil-rich site in the south of New Zealand has been met with fierce criticism and a campaign to protect it in perpetuity.

    Foulden Maar, near Dunedin, is arguably the most important terrestrial fossil site in New Zealand. It comprises a complete ecosystem. This makes it one of the most important sites from the Miocene in the southern hemisphere and comparable to the famous UNESCO-protected Messel Pit in Germany.

    Rights: Tony Millet

    Pupuke Moana (Lake Pupuke)

    Pupuke Moana (Lake Pupuke) on the North Shore of Auckland is a good example of a maar. It is the crater of a scoria cone volcano that last erupted around 140,000 years ago. The lava from explosions at Lake Pupuke trapped many trees, which have become fossilised. These are still visible at Takapuna beach.

    Acknowledgement: Google Earth

    A maar is a small deep volcanic crater lake. Foulden Maar formed 23 million years ago after an explosive eruption. It contains tens of thousands of exquisitely preserved fossils of plants and animals, all of which represent extinct biodiversity.

    Rights: Daphne Lee, CC BY-ND

    Fossil diatoms

    A scanning electron microscope image reveals fossil diatoms, present in their billions at Foulden Maar.

    The fossils are preserved between layers of diatomite, itself the fossilised microscopic remains of siliceous aquatic algae called diatoms. Plaman Resources, a majority Malaysian-owned subsidiary of Australian company Plaman Global, has applied to create an open pit mine to extract the diatomite, trademarked as ‘black pearl’, to turn it into pig and poultry feed.

    This would be like mining volcanic ash at Pompeii for pig food.

    Community and scientific concerns

    The protests by the science community and the public were sparked in April 2019 by a leaked report by investment banker Goldman Sachs, which said that “an appeal … is likely to come from a small number of local residents, who are not well resourced”.

    The Save Foulden Maar petition has since reached over 10,000 signatures. Some big names are supporting it, including New Zealand’s former Prime Minister Helen Clark.

    The economic case put forward by Plaman Resources in its application to the Overseas Investment Office has been heavily criticised and described as unjustifiable vandalism. New Zealand and international scientists have challenged the scientific case for black pearl as a food additive for stock.

    Public and scientific opinion has since changed Dunedin City Council’s position. At first, the council supported the mine, but it has now promised to protect Foulden Maar for scientific research and educational purposes. The University of Otago has also called for the site’s protection. Both institutions have now formalised their opposition through submissions to the Overseas Investment Office.

    Meanwhile, Plaman Resources tried to shore up support by offering monetary inducements to the University of Otago if it dropped its opposition to the mine. The company also proposed a swap between Foulden Maar and the 15-million-year-old Hindon Maar fossil deposits. The latter has no diatomite deposits that are economically viable for Plaman, but for palaeontologists, this would be like having to choose between the pyramids of Giza or the Sistine Chapel.

    Precious fossil site

    Until recently, Foulden Maar was known mostly to the scientific community but had no public profile to ensure ongoing access to the site.

    Rights: Stella McQueen, CC BY-SA 4.0

    Galaxiid fossil

    Galaxias effusus holotype fossil from Foulden Maar. This is the oldest galaxiid fish in the world.

    The maar crater formed 23 million years ago, filled with a small hydrologically closed lake that gradually filled in and preserved an entire subtropical rainforest ecosystem that once flourished there. It links New Zealand to what was occurring at the time in New Caledonia, Australia and even South America.

    The site is about a kilometre wide and nearly 200 metres deep. It contains fossils of plants and animals that lived in the lake and surrounding rainforest, including the world’s oldest galaxiid fish (whitebait) and scale insects on leaves. Of the tens of thousands of exquisitely preserved fossils, only 30 have been described so far by the international team working at the site.

    Research at the northern hemisphere equivalent, the Messel Pit, has been ongoing for over a century and shows no signs of slowing down. There are hundreds of new species yet to be described at Foulden Maar. Each fossil must be painstakingly separated from its diatomite tomb and preserved – a process that can take around a week per fossil. Bringing this lost world to life is incompatible with the Plaman Resources proposal for a 24/7 operation.

    Hidden climate record

    There is more to Foulden Maar than the fossils. At its deepest point, it preserves a unique climate record covering 120,000 years. It is the only site in the southern hemisphere with a climate record that shows annual resolution of this kind and links between the tropics and Antarctica 23 million years ago.

    Rights: Thin Ice/University of Waikato

    Fossil plants as paleoclimate proxies

    Professors Jane Francis and Matt Huber explain how fossilised plants are one of several proxies used to form a picture of past climates and ecosystems.

    Data from the site is being used in predictive global climate models. There is no way in which the full thickness of the maar lake could be preserved for ongoing climate research if the mining proposal went ahead.

    The fight ahead

    Foulden Maar needs legal protection from mining in perpetuity. New Zealand has a number of legal frameworks that govern land use and protection such as the Resource Management Act. There are also regional plans that are managed by local councils. A change would likely be required to one of the legal frameworks in order to protect Foulden Maar.

    Rights: Jennifer Bannister, CC BY-ND

    Fossil leaf from Foulden Maar

    A fossil leaf (family Cunoniaceae) from the early Miocene fossil deposit Foulden Maar.

    Lee, D.E., Kaulfuss, U., Conran, J.G., Bannister, J.M. & Lindqvist, J.K. (2016). Biodiversity and palaeoecology of Foulden Maar: An early Miocene Konservat-Lagerstättedeposit in southern New Zealand. Alcheringai: An Australian Journal of Palaeontology, 40(4), 525–541.

    Ideally, Foulden Maar could link in with the Waitaki Whitestone Geopark, which will soon be proposed as New Zealand’s first UNESCO Global Geopark, promoting scientific research and fossil tourism. This proposal, championed by Helen Clark, includes over 40 geological sites, including a goldfield of international scientific importance at Nenthorn, just north of Foulden Maar.

    Nature of science

    Scientists – and the general public – use their science understanding to participate and contribute to socio-scientific issues like the potential mining of Foulden Maar. This article by Dr Nic Rawlence is a real-life illustration of how Nic is engaging with this issue. Nic is applying the science capabilities – the use of data, evidence and representations – to share scientific information in a way that will spark a deeper interest and encourage his peers and the wider community to engage with science.

    Our fight to protect Foulden Maar will no doubt continue. Plaman Resources has indicated it will appeal any decisions to protect the site. The company has also threatened to mine the section it already owns if it doesn’t get approval to buy a neighbouring farm to make its operation economically viable.

    Misconceptions remain, such as a Dunedin city councillors comment that the “climate change record of the time is less significant than the fossils and … people could already research the climate at different periods in time on the internet”. This is like saying we don’t need cows to produce milk as we can buy it from a dairy.

    It is nearly 50 years since concerned New Zealanders joined forces to stop an aluminium smelter being built at Aramoana at the head of Otago Harbour. Foulden Maar is our generation’s Aramoana.

    In the best interests of the fossils, the locals and scientific research, Plaman Resources should walk away from this. Mining is littered with bad investments. Write this off as one of those.

    Related content

    One of New Zealand’s most exceptional fossil sites may soon be open to scientists again following a land purchase that saved it from commercial mining.

    The Connected article Foulden Maar: fossils or food? prompts critical thinking and ends with a call to social action.

    Learn about the formation of maars in Auckland’s volcanoes.

    Find out about some of the different ways scientists date fossils in Dating the past – introduction and Date a dinosaur.

    The article Why caves matter explains how cave formations can inform us about the past.

    Socio-scientific issues

    Addressing socio-scientific issues in the classroom has been shown to increase students’ understanding of science content, science processes and the nature of science, as highlighted in the article The ‘Participating and contributing’ strand.

    Hub resources that look more closely at specific socio-scientific issues, along with ethical and pedagogical help, include:


    Foulden Maar has been used in research around past climates. Learn more about this field – paleoclimatology – in Clues to the past, Carbon dioxide and climate and the video Fossil plants as paleoclimate proxies.

    Students can take part in a citizen science project, Fossil Atmospheres. The project is comparing some features of fossilised plants with the same features of plants living today to learn more about the effect of changing carbon dioxide (CO2) levels in our atmosphere.

    To follow media articles and reports on Foulden Maar, go to our Pinterest board.

    Useful links

    Buried treasure, an article from New Zealand Geographic, has a good explanation of the formation of a maar lake.

    In the original publication of this article by Dr Nic Rawlence, a number of academic papers and news articles were cited to support the different claims and statements made. These include a leaked report to a local Otago newspaper, which brought the proposal to mine Foulden Maar to public attention.

    Save Foulden Maar is an action group that has been set up by concerned parties who oppose the proposed mining of the Foulden Maar site.

    Foulden Maar has been compared to the UNESCO-protected Messel Pit in Germany.

    A number of experts have challenged the notion of diatomite as a stock food supplement. Read about the challenges in the news article Fossil-dirt nutrition claims under doubt.

    Read a news article about Financial incentives offered for fossil mining support.

    A geopark is a defined area of international geological significance that tells the story of how the geology and landscape have shaped the lives of its inhabitants, be they people, animals or plants. It is a new UNESCO designation. The Waitaki Whitestone Geopark in the South Island is seeking to be the first designated geopark in Oceania.

    Learn about the Save Aramoana Campaign, where people fought to stop a proposed aluminium smelter in the late 1970s.

    Leaf fossils from Foulden Maar have played a role in paleoclimatology research, showing a significant ice melt 23 million years ago in Antarctica coincided with a spike in CO2.

    To date, only 30 of the tens of thousands of fossils discovered at Foulden Maar have been described. Read about some of these in Biodiversity and palaeoecology of Foulden Maar: an early Miocene Konservat-Lagerstätte deposit in southern New Zealand.

    Research suggests links between the Foulden Maar site 23 million years ago and New Caledonia, Australia and South America. This research is published in A unique annually laminated maar lake sediment record shows orbital control of Southern Hemisphere midlatitude climate across the Oligocene-Miocene boundary.

    This 2022 RNZ (Radio New Zealand) story about University of Otago scientist Daphne Lee’s new book Fossil Treasures of Foulden Maar provides a glimpse into this paleontological site, include is an interview and lots of beautiful images.

    UPDATE: In January 2023 Dunedin City Council announced that it had reached an agreement to buy the Foulden Maar mining site. Read this RadioNZ news story.


    This article was written by Nic Rawlence, Lecturer in Ancient DNA, University of Otago. The article was originally published on The Conversation. Read the original article.

    Rights: The Conversation

    The Conversation

    The Conversation is an independent source of news and views, sourced from the academic and research community and delivered direct to the public.

    The Conversation

      Published 23 July 2019, Updated 8 August 2023 Referencing Hub articles
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