Foulden Maar, a fossil site near Middlemarch in Otago, New Zealand, formed in a volcanic eruption 23 million years ago. The resulting crater lake filled with diatomite, composed of layers of silica-shelled algae (diatoms) and exceptional fossils of plants, fishes, spiders and insects from the surrounding sub-tropical Miocene forest. As the only known maar of its kind in the Southern Hemisphere, it is one of New Zealand's pre-eminent fossil sites. A 2018 proposal to mine Foulden Maar for livestock-food additive has attracted significant public opposition.
Foulden Maar pit as seen from Moonlight Road
|Location||Otago, New Zealand|
Foulden Maar is named for the nearby farm of Foulden Hills, itself probably named after the town of Foulden in the Scottish Borders. Many other local locations—such as Kelso, Ettrick, Roxburgh, and the nearby Nenthorn—are similarly named.
Foulden Maar is a maar-diatreme volcano in the Strath Taieri, southeast of Middlemarch in Otago, New Zealand. Its crater was formed 23 million years ago and is filled with fossilised diatomite as well as sedimentary rock, debris ﬂows, and pyroclastic rocks. Foulden Maar is in the Waipiata Volcanic Field, which is an eroded phreatomagmatic eruption site.
The Foulden Maar crater is approximately 1,000 metres (3,300 ft) in diameter; its diatomaceous layer is estimated to be 200 metres (660 ft) deep. The Foulden Maar lake formed in a volcanic crater during the Waitakian (early Miocene), approximately 23 million years ago. It was deep and anoxic at the bottom, which precluded decomposition of plant and animal remains. The lake was hydrologically isolated, meaning that no rivers or streams disturbed the sedimentation, which formed multiple laminated layers. These thin layers of silica are known as diatomite, as they are composed primarily of one diatom species, Encyonema jordaniforme Krammer, that grew on submerged rocks or aquatic plants in the lake. As the lake gradually filled in and dried out, the diatomite layers capture a detailed fossil record of about 130,000 years.
Foulden Maar is one of New Zealand's pre-eminent fossil sites, and is unique in the Southern Hemisphere for the time period it covers. Fossils were first discovered at the site by gold prospectors in the early 1870s and were described as "polishing powder" by the geologists Frederick Wollaston Hutton and George Ulrich in 1875.
Although excavations have been limited to a small area the size of a tennis court, palaeontologists have discovered hundreds of undescribed species. The sediments are rich in fossil flowers, fruits, seeds, pollen, and bark from plants, as well as fungi. Several new species of plants have been discovered, and the fossil plant genus Fouldenia is named in honour of its type locality Foulden Maar.
Fossilised freshwater fish are common. The earliest galaxiid fish fossil and the earliest known fossilised eel both come from Foulden Maar. Numerous arthropod fossils have been found at the site, among them Araneae (spiders), Plecoptera (stoneflies), Odonata (dragonflies), Isoptera (termites), Hemiptera (true bugs), Diptera (true flies), Coleoptera (beetles), Trichoptera (caddis flies), and Hymenoptera (wasps, ants and bees). The four arachnids found at Foulden Maar are the first arachnid fossils identified in New Zealand; previous spider specimens had been found in amber but were not identifiable. The first fossil hymenopteran in New Zealand is an ant found at Foulden Maar.
University of Otago students visiting the fossil site in 2006
The fossil evidence derived from pollen and spores suggests a warm temperate or sub-tropical rain forest with canopy trees, with an understorey of shrubs, ferns and on the margins pioneer species. Climatically, the area resembled modern-day south-eastern Queensland with species that no longer occur in the New Zealand flora. The lake contained small and large galaxiid fishes and eels, ducks (inferred from coprolites), and likely crocodiles as well.
Leaf fossils from the deposit have been used to link past spikes in carbon dioxide levels with melting of Antarctic ice, and the variations in the laminations of the diatomite have been studied to reveal the New Zealand climate from that time.
Diatomite was extracted in small quantities from the site during World War II when transport difficulties hindered access to foreign sources. Diatomite has a range of applications, depending primarily on purity, diatom size, and the trace elements present.
Foulden Maar is on privately owned land. The area was initially developed for mining by Featherston Resources Ltd in 1997. The deposit was estimated as 5 milion tonnes (Mt) by NZ Petroleum and Minerals. This proved uneconomic for the company, and its assets were sold to Plaman Resources Ltd in March 2015.
Plaman Resources claim the size of the deposit is 31 Mt. The shareholders for Plaman Resources, are Iris Corporation, Kuala Lumpur, Malaysia (50.95 per cent) and Burleigh Nominees Ltd, Douglas, Isle of Man (49.05 per cent). Plaman Resources' shareholders, the Iris Corporation and Burleigh Nominees, have allegedly been involved in corruption and humans-rights abuses and have unpaid debts. It is unclear if Iris Corporation would remain a shareholder of Plaman if Overseas Investment Office (OIO) approval for the mine is received.
Plaman hold the mining rights and plan to turn all of the fossil-containing diatomite into an additive for incorporating into the food of intensively farmed animals such as ducks and pigs. Initial seed funding of about US$20 million (NZ$28 million) was raised through Goldman Sachs New Zealand Holdings, the Auckland branch of New York stock-exchange listed investment bank in August 2018. The financial viability of these plans is reported to hinge on the purchase of an adjoining farm, which the OIO must rule on. No timetable has been set for the decision. The proposal would involve building a new $36.8m processing plant at Milton to crush the diatomite before shipping offshore from Port Chalmers or Bluff. It is estimated by the company that the trucking and processing would create 100 jobs over 27 years. Plaman has discussed with local councils applying to New Zealand's Provincial Growth Fund for help with the costs of building the processing plant, although no application has been made.
Previous mining at the site yielded low-quality diatomite only suitable for inclusion in concrete, rather than the high-quality product Plaman is marketing as "Black Pearl". Plaman claims that livestock will benefit nutritionally from Black Pearl, because the diatomite is "rich in natural organic matter (which contains humics, such as humic and fulvic acid) and other valuable nutrients, which have been shown to be beneficial in animal nutrition." Animal nutrition experts expressed doubt that the product produced by Plaman will have any animal-health benefits, as there is no published data to support their claims. Concerns have also been expressed by the New Zealand Green Party that the diatomite would be sold as fertiliser to support the production of palm oil.
Plaman Resources have offered to refrain from mining nearby Hindon Maar if opposition to the Foulden Maar proposal is dropped. They have also offered to set aside 5 hectares (12 acres) (12–20% of the deposit) of the eastern pit at Foulden Maar for scientific research, but geologists say that if the deposit is drained for mining the fossils may be lost regardless.
The company was placed in receivership and voluntary liquidation in June 2019, and the OIO approval process placed on hold. The Save Foulden Maar group is considering crowdfunding to permanently protect the site.
Some locals are opposed to the anticipated levels of dust, noise, and general disruption the proposed mine would create. The Otago Regional Council has granted Plaman Resources resource consent to discharge air dust for the purpose of quarrying diatomite until 1 July 2020. The original mining permit was for 20 years but has since been extended to November 2033. A wider group of people concerned about the loss of the unique fossil record described as "Dunedin's Pompeii" and an "irreplaceable treasure box" have launched a petition to preserve the site, garnering nearly 10,000 signatures in the first month. A leaked report by Goldman Sachs details the engagement of former Labour MP Clayton Cosgrove as a lobbyist to "secure approval" for the mine.
Some locals would like to see the area turned into a geo-park, along similar lines to other diatomite sites in Norway, Germany, and China. Former Prime Minister Helen Clark suggested that the site could be protected as a scientific reserve under the Reserves Act 1977, saying "It just doesn't stack up. It's a question of values. Do we value knowledge? Do we value natural heritage? Do we value science and research, or do we just want to a quick dollar from a low value pit? I mean, really, it's distressing." MP Clare Curran voiced support for the mining proposal, saying that she had been given assurances by Plaman. She argued that "misinformation" was abundant due to the slow overseas-investment-approval process and said that the resource-consent process would still need to be followed. Dunedin Mayor Dave Cull, who wrote a letter of support for the mining proposal, has publicly called for clarification from Plaman after hearing details of the leaked Goldman Sachs report. Clutha Mayor Bryce Cadogan, who also supports the proposal, expressed frustration that commercial sensitivity prevented the release of all the information in favour of the mine. Dunedin City Council councillor Aaron Hawkins proposed that the council should "recognise the importance of Foulden Maar, and support its preservation, and protection as a scientific resource", and the council voted to do so, later formally opposing the mining proposal. The University of Otago is also formally opposed to the mining proposal. Sir Alan Mark, chair of the environmental group the Wise Response Society, called for the government to purchase the site and establish a geological reserve.
Juliet Gerrard, the Prime Minister's Chief Science Adviser, has said that "the tale is far from simple and at least two weak spots at the interface of science and policy are exposed as we dig through the complexities: there is no obvious point in central government to consider the value of a fossil record; and the science community has perhaps not previously sufficiently communicated the national and international value of this geological site." The Geoscience Society of New Zealand has called for the mining proposal to be stopped, with President Jennifer Eccles saying, "New Zealand’s national identity is strongly bound to its unique plants and animals. We cannot stand by and see this fountain of paleontological knowledge about where we have come from destroyed; particularly not for so little transient local and national gain."
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