Phosphorus (P) is a non-metallic element which is almost always present in a maximally oxidised state (PO43-) as inorganic phosphate rocks due to its reactivity. Elemental phosphorus can exist as red and white (known to students in chemistry classes and once used in warfare but not found as a free element in nature). It is one of the essential building blocks of life and life simply wouldn’t exist without it. It is a key component of DNA, RNA, ATP and phospholipids and is essential to cell development, reproduction and in animals, bone development.
The use of phosphorus compounds in fertilisers is due to the need to replace the phosphorus that plants remove from the soil. There is no substitute for this element. In the mineral form of phosphate rock (mostly the apatite family of minerals) is not bioavailable to plants. It must be processed to convert it to a plant-available form. The mined product is is used to produce phosphoric acid which is then used to produce fertiliser products.
In this post I discuss a couple of ‘terrestrial’ phosphate deposits well known for associated bones.
Of these the Wellington Caves phosphate deposit in New South Wales is far more terrestrial than the West Coast Fossil Park one in South Africa. The former is well inland in part of NSW which has not seen the sea since the Devonian period. The latter was inundated by Tertiary high level sea and the fossils although mainly or terrestrial animals were likely deposited in peri-marine environments near a river mouth.
Phosphatic rocks go by the names of phosphorite, phosphate rock or rock phosphate. The most appropriate choice of name may depend on the interpretation of origin. At Wellington Caves the substance that was mined is probably best called phosphate rock. The more extensive stratified bed of phosphatic rock, often marine sediments, are usually called phosphorite.
Most of the world’s commercial phosphorite (used in fertiliser manufacture) is actually from marine deposits.
Phosphorites are calcium phosphate-rich sedimentary rocks, generally considered to have more than 15% phosphate content.
Texturally, phosphorites can be obviously granular, with fossil fragments or oolites or peloids or lithic fragments, or they can be composed of extremely fine-grained, phosphate-rich mud. Compositionally, the phosphate component in phosphorites is principally a mix of apatite minerals: chlorapatite (Ca5(PO4)3Cl), fluorapatite (Ca5(PO4)3F), hydroxyapatite (Ca5(PO4)3OH)), and carbonate fluorapatite (Ca10(PO4,CO3)6F2-3).
Phosphorites are generally marine sedimentary rocks and they are known in sequences ranging in age from Precambrian to Holocene. In modern oceans, they tend to occur along the eastern margins of some ocean basins where deep-water upwelling occurs under areas of high biologic productivity.
One of the most famous phosphorite unit is America’s Phosphoria Formation.
A piece of Phosphoria Formation phosphorate is shown below, as can be seen it is not a remarkable looking rock, looking just like dark sandstone.
Phosphorite can be explored for in the field with a reagent that turns the rock yellow if appreciable phosphate is present.
Since agriculture is nationally important, phosphorite can be considered a strategic material.
In the sphere of environmental opposition to mining phosphorite has been noteable on account of the “Phosphorite War”. This is the name given to a late-1980s campaign in the then-Estonian Soviet Socialist Republic, against the opening large phosphorite mines in the Virumaa region. The movement, which peaked in 1987, was successful in achieving its immediate goals, but is also regarded by some historians as influential in strengthening the nationalistic movement which led to the restoration of Estonian independence in 1991. There was fear in Estonia that the new mines’ need for a workforce would start a wave of migration, bringing tens of thousands of workers from other parts of the Soviet Union to Estonia (the proportion of Estonians in Estonia had already dropped from about 97% immediately after World War II to 61% in the late 1980s. The Estonian phosphorite deposits are in the Obolus sandstone at the Cambrian/Ordovician boundary. These deposits include the largest phosphorite deposit in Europe, and they had started to be mined in the 1920s. The central government of the Soviet Union in Moscow took interest in exploiting the phosphorite deposits in Lääne-Viru County in the early 1970s. The plan became known to the general public on 25 February 1987 when revealed on Estonian TV. Numerous protests broke out and lead to an unprecedented size public debate later that year. Faced with wide opposition to the new mines, the Soviet authorities abandonned the plans by 1988. Although it might not have been intended or foreseen by the original environmental campaigners, the “Phosphorite War” activated the Estonian masses to the power of collective action for overcoming fear of the regime. This is why it is said that it acted as catalyst for the destabilization of the Soviet government in Estonia ( http://en.wikipedia.org/wiki/Phosphorite_War ).
The general principle for expecting phosphate enrichment in sediments is associated with still-stands in sedimentation and/or the influence of phosphate-rich deeper seawater at areas subject to ‘upwellings’ ( http://en.wikipedia.org/wiki/Upwelling ). The most common occurrence of phosphorites are related to strong marine upwelling of sediments. Upwelling is caused by deep water currents that are brought up to coastal surfaces where a large deposition of phosphorite may occur. In addition to uprisings, estuaries themselves are also known as phosphorus entrapment places. This is because coastal estuaries contain a high productivity of phosphorus from marsh grass and benthic algae which allow an equilibrium exchange between living and dead organisms.
Wellington in New South Wales is on the N-S running “Molong High” (a.k.a. Molong Geanticline) which is interpreted as a Lower Palaeozoic palaeogeographic high (volcanic high?) flanked by areas of deeper water. The Molong High/Geanticline is rich in andesitic volcanics and also had abundant limestone deposition in each of the Ordovician, Silurian and Devonian (Early Devonian) periods. In case upwelling, as described above, had occurred against the Molong High and enriched any of the marine sediment in phosphate, this area was extensively explored for phosphate. No marine phosphorite was found. The region does have many small phosphate deposits. These are of cave filling type and the phosphorus may have come from bat guano and/or bones.
The Wellington Caves phosphate deposit is one of these cave filling type deposits, and the only one in the region that was ever attempted to be mined on any significant scale. Smaller deposits elsewhere along the Molong High was mined and very quickly exhausted in the 1800s. The Wellington Caves phosphate mine had a lot of development work put in, and it did produce some phosphate rock but overall the operation probably resulted in a sizeable loss of money.
After the crossing of the Blue Mountains, Wellington became a distant military outpost in the Colony of New South Wales. A painting by Augustus Earle ca. 1826 (nla.pic-an2818409-v) clearly shows the entrance to what is today called Cathedral Cave at Wellington Caves . This painting is labelled ‘Mosman’s Cave’ (who was Mosman?). The first written account of the caves was by explorer Hamilton Hume in 1828. Two years later the local magistrate George Ranken reported and collected fossil bones. Due to Ranken’s exertions there, this is possibly the first site from which fossils were collected for scientific study in Australia. The Wellington Caves bones were sent to England for determination. From them the genus Diprotodon was erected and a giant kangaroo species was recognised.
Ranken took the NSW Surveyor General Thomas Mitchell (later Sir Thomas) to the caves and Mitchell collected a large quantity of the bones to dispatch to England. They were subject of an address by Mitchell to the Geological Society of London in 1831.
In 1884 the Wellington Caves were declared a natural reserve and in the following year organised tours began, with James Sibbald appointed caretaker.
The Phosphate Mine was developed during WWI, in 1914-1918, and probably produced about 6000 tons of phosphatic rock, despatched from Wellington by rail. Where the phosphate rock was sent to and processed I have not yet traced.
The Wellington Council cleaned out the old mine passage and installed electric lighting in 1996, to enable tourism.
The phosphate mine is essentially part of the caves system, which by 2005 was receiving 50,000 vistors annually.
Apart from viewing the old workings, visitors can see the ?800,000 year-old phosphate and bone breccia deposits containing fossil bones. A number of loose bones have been piled on a dirt shelf in one part of the mine where visitors can pick them up and examine them.
Wellington Caves phosphate mine
The tourist brochures describe this site as the “Wonder of the West” and that “The Caves and Phosphate Mine complex is one of the world’s most significant fossil sites and specimens from Wellington are included in collections at museums around the world”.
Bones can be seen at the phosphate mine, a very popular tourist stop. ( Photos: http://brennansaroundaus.blogspot.com.au )
Walking through the restored underground mine one may learn about past mining techniques, along with the history of the area. In some sections there are walls full of un-excavated bone fragments from 300,000 years ago. Towards the end of the tour you actually get to handle some bones that have been found on the site.
The Wellington Caves and phosphate mine (Sources: Tourists October 1, 2010 )
Map of the phosphate mine at Wellington Caves.
The Wellington Caves phosphate mine is an old phosphate mine at Wellington Caves, situated a few kilometres south of the town of Wellington in NSW.
The production figures for phosphate rock from “Wellington”, presumably entirely from this mine, are:
1914 – 700 tons ; 1915 – 1,110 tons ; 1916- 2,002 tons ; 1917 – 2,000 tons ; 1918 – 300 tons.
Most of the best rock was extracted in 1916 it seems, for although a similar amount of rock was railed off in 1916 it brought a lesser return and so grade must have fallen off after 1916. The site was virtually worked out in 1918.
The mine has been renovated and opened up for tourists by the Wellington Council. It is regarded as one of the best tourist mine attractions in the State. Wellington Council says: “The mine not only features the workings of a World War 1 mine, but bone fragments and fossils from 300,000 years ago. Paleontologists from all over the world have been making pilgrimages to this cave since the 1930s and now you can too!”
Layers of calcite (dogtooth spar) cave rock over white phosphorate layer, and close-up.
( Photos: OzLadyM – http://ozladym.com )
One of the bones. ( Photo: Vanessa M )
Diprotodon skeleton (model). This is the genus of giant marsupial which the site is best known for.
A Heliolites coral in the Devonian limestone (Garra Formation) that the caves are developed in. ( Photo: LadyOzM )
The Wellington Council has also developed at the Wellington Caves a Fossil Trail along which one may find noteworthy specimens of marine invertebrates in the Garra Formation limestone that the caves (and phosphate deposit) have formed in.
WHAT REALLY HAPPENED AT THIS PLACE IN WWI?
I personally suspect it was just another “failed” or unsuccessful mining venture, likely spurred by commercial need due to WWI cutting shipping supplies and so on – as also affected other commodities (e.g. for copper, causing the Great Cobar copper boom in WWI further west in NSW).
However I have not tried to investigate the matter closely for myself and some note may be made of the rumours one will encounter in Wellington, from the Council or Tourism office, or from the cave guides.
They may tell you of a “giant cover up” and this has been written up by the Sydney Morning Herald (at http://www.smh.com.au/travel/lowdown-on-a-giant-cover-up-20100716-10dj6.html ). The only thing lacking is proof but the story runs as follows:
“Scratch the surface in Wellington, a peaceful farming town about a half-hour drive south-east of Dubbo in central-western NSW and you’ll soon uncover a dastardly tale of deception, intrigue and paleontological larceny on an international scale; a mining mystery involving 300,000-year-old three-tonne wombats and an illegal trade in rare bones”.
“The scene of the alleged crime is an old World War I-era phosphate mine on the grounds of Wellington Caves Reserve. Today, it’s a veritable time tunnel that has been preserved and restored to show just what it would have been like to work in an underground mine almost 100 years ago, complete with original timber sets and nails, old train tracks and pick marks on the walls”.
“But before it was a mine, it was a cave, according to guide, Bruce Day, and home to vast colonies of bats that left behind tonnes of droppings, or guano, rich in phosphates. The New South Wales Phosphate Company began mining the cave, by hand, in secret, in 1914. By the time the mine was abandoned five years later, 6000 tonnes of phosphate had been removed for fertiliser. But according to Day, 6000 tonnes is a pretty poor yield and the phosphate was of poor quality. What they were really after, he reckons, were bones”.
“Despite all the visitors, many of whom left traces of their explorations on the cave walls in the form of black carbon from their candles, oil from their hands and, in some cases, graffiti, no one in Wellington had any idea the phosphate mine was working for the first two years of its operation.”
The SMH article concludes with “The real answer about exactly what was extracted from the mine will probably never be unearthed but, in the meantime, Day’s tale of fossil intrigue makes for a fascinating tour”.
This article says that cave guide Mr. Day thinks that bone diggers looking to make a quick buck from the illegal sale of the bones, were a “possible reason why there are no known records of what really happened during the five years the mine was operational”.
This would be an interesting little supposed ‘mystery’ to follow up. Did the Council not know? Indeed when was the Wellington Council formed? The Wellington Council website is at http://www.wellington.nsw.gov.au but it does not appear to have a history of itself there(?). Although it does have a webpage about itself ( http://www.wellington.nsw.gov.au/council/about-council ) this really describes the Wellington local government area rather than the Council itself.
Last year the Council actually had planned to convene a seminar on geological/mining history and heritage. For some un-ascertained reason, however, this did not eventuate as planned. Hopefully it is still planned to hold it some time in the future.
West Coast Fossil Park, Langebaan. South Africa
Location of the fossil park, near Langebaan
This fossil park is close to Langebann and is associated with the West Coast National Park along the Atlantic coast.
This too was a phosphate mining area, where extraction began in 1943. Similarly as at Wellington, many tons of fossils were possibly crushed along with the rock that was made into fertilizer. Although many fossils were doubtless destroyed by mining, the mining also brought the fossiliferous nature of the area to light and over a million specimens have been collected and stored in the Iziko: South African Museum in Cape Town. The area is probably one of the richest fossil sites in the world, and one with the greatest diversity of 5 million year old fossils; , well-suited to document the global climate and environmental changes that were taking place during the Late Miocene to Early Pliocene transition. Thus far over 200 different animal species have been identified from the bones, which is why it may have the greatest diversity of five million year-old fossils found anywhere in the world
A recent (2011) major interpretation of the area is this one:
Regional and global context of the Late Cenozoic Langebaanweg (LBW) palaeontological site: West Coast of South Africa
- David L. Robertsa, , Thalassa Matthewsb, Andrew I.R. Herriesc, Claire Boulterd, Louis Scotte, Chiedza Dondoa, Ponani Mtembia, Claire Browninga, Roger M.H. Smithb, Pippa Haarhoffb, Mark D. Batemand
a Council for Geoscience, PO Box 572, Bellville 7535, South Africa ; b Iziko South African Museum, Cape Town, South Africa ; c John Goodsell Building (F20) Room 312, University of New South Wales Kensington, Sydney, NSW, 2052, Australia ; d Sheffield Centre for International Drylands Research, Department of Geography, University of Sheffield, Winter Street, Sheffield, S10 2TN, UK ; e Department of Plant Sciences, University of the Free State, Bloemfontein, South Africa.
The palaeontological site of Langebaanweg is internationally renowned for its prolific, diverse and exceptionally well preserved Mio-Pliocene vertebrate fossils. The site is ideally situated to document the complex interactions of ocean, atmosphere and land and their respective influence on climate evolution, given its location near the coast and mix of marine, estuarine and terrestrial faunas and depositional settings.
During the Oligocene drawdown in sea levels, the landscape was etched by river incision. Fluctuating sea levels of the Neogene periodically reversed the trend from erosion to deposition, preserving contemporary faunas and floras in the Oligocene palaeovalleys. Earlier Miocene pollen from fluvial facies indicates a humid sub-tropical climate, reflecting a warm southern Atlantic Ocean. The abrupt late Middle Miocene global cooling (Monterey Excursion) coincided with intensified cold upwelling in the Benguela Current and extensive phosphate authigenesis. A globally documented Early Pliocene highstand possibly related to the shoaling of the Isthmus of Panama reached ~ 90 m above sea level (asl), implying extensive melting of the cryosphere.
Palaeomagnetic data in tandem with global sea level reconstructions suggest an age of ~ 5.15 ± 0.1 Ma for the faunas and a correlation with the earlier part of this transgression. A subtropical C3 vegetation is indicated by the faunas and floras, but with a significant contribution by sclerophytic fynbos pointing to a cooler and more seasonal climate than in the Miocene. A mid-Pliocene highstand to ~ 50 m asl truncated the Early Pliocene succession and the globally documented Late Pliocene highstand to ~ 30 m asl saw the Atlantic shoreline approaching the park area for the last time. With the progressive climatic cooling and instability of the terminal Pliocene, culminating in the growth of the Arctic ice cap, strengthening southerly winds driven by a tighter coiled South Atlantic Anticyclone deposited extensive coastal dune fields over the region.
The phosphorate mining here was in the 5 million year old Muishond Fontein Phosphorite Member, which is a pelletal textured phosporite.
Fossil Park is in the sediments of the former Langebaanweg ‘E’ Quarry. These sediments form part of the Varswater Formation which is in turn part of the Sandveld Group as shown in the above section. The Varswater Formation is underlain by the Middle Miocene Elandsfontyn Formation, or otherwise by Neoproterozoic/Cambrian bedrock.
Overlying the Varswater formation is calcareous aeolianite of the Langebaan Formation, or else the unconsolidated quartzose aeolian sands of the Springfontein Formation.
The Varswater succession consists of four members, the oldest of which (The Langeenheid Sandy Clay Member) probably dates to around the early Middle Miocene . The Clay Member is overlain by the Middle Miocene Konings Vlei Gravel Member (KVGM). Above the Konings Vlei Gravel Member is the Langeberg Quartzose Sand Member (LQSM), which in turn is overlain by the younger Muishhond Pelletal Phosphate Member (MPPM).
The LQSM and the MPPM are the main fossil bearing deposits of the formation. The latter contained the commercially exploitable phosphate ore mined at Langebaanweg.
The LQSM represents a number of different depositional environments, and although some sub-aqueous deposition of fossils does appear to have taken place, the majority of fossils are thought to have been accumulated on a flood plain.
The MPPM may have accumulated in river channels.
Conceptual model explaining the fossil occurrences in the LQSM and MPPM: A), Terrestrial to marginal marine palaeontological settings of the LQSM ( ~ 25 m asl); B), MPPM Estuarine conditions with phosphate authigenesis with further transgression to ~ 30 m asl; C), Glacio-eustatic regresssion to below 25 m and incision of ephemeral streams and concentration of fossils from different environments in channel lag; D), transgression and a return to Estuarine conditions (MPPM).
Bone bed (Channel 3aN) at the dig site, with the large fossils mainly consisting of the short necked giraffid Sivatherium hendeyi. Note the lack of orientation of the long bones and steep (southwesterly) dip of the channel base (in (A) towards viewer).
Prior to the current Park administration and more carefully controlled excavation, Brett Hendey excavated in 1976, right next to the excavation currently open to the public. Hendey excavated in meter squares, leaving “witness sections” (of 1 meter square) every so often. This was where Hendey found a near complete skeleton of the African bear Agriotherium africanum ( which was the first known bear found in Africa south of the Sahara).
As the area is excavated, mapped and sediment samples taken, the fossils are left in situ and incorporated into the public tourism area. The only fossils removed from the excavated area in future will be ones of specially important scientific value.
Sivathere jaw ( an extinct group of long-horned, short-necked giraffids )
Fossils finds at this area include the African bear, an extinct seal and four extinct penguin species. Other large mammals include sabre-toothed cats, two kinds of elephant, ancestors of the white rhino, wildebeest and giraffe, three-toed horses and antelope.
In addition over 20 marine invertebrats are recorded, along with land-dwelling insects and snails, fish, frogs, reptiles, 85 bird species, etc.
Some of the snails
Under the new Park administration excavation resumed at Hendey’s site in 2008. Three experienced excavators participated, namely Deano Stynder (Iziko SA Museum), Lloyd Rossouw (Bloemfontein National Museum), and Pippa Haarhoff (West Coast Fossil Park). We had three volunteers sorting material under the supervision of Albrecht Manegold (Forschung Institute, Germany).
The work focussed on an area in the LQSM sediments which lay between Hendeys MPPM witness sections, and an area of one-and-a-half square meters was excavated. Finds included bovid horn-cores and the remains of hyena? coprolites associated with large bones. During the course of the excavation, Lloyd Rossouw took soil samples for phytolith analysis and this report has been published in the South African Journal of Science (2009, Volume 105).
Tourists at the site.
Although the focus of the Fossil Park is on the Tertiary, there is also a Quaternary archzaeological site within the park boundaries. This is the Anyskop Blowout. Archaeological materials were first discovered in the late 1970s atop a prominent hill called Anyskop, located about one kilometre south of the famous fossil beds of Langebaanweg. In 2001 and 2002 a team of researchers from the Department of Early Prehistory and Quaternary Ecology of the University of Tübingen, Germany conducted extensive collections and detailed excavations of the archaeological sites atop Anyskop. The archaeological remains collected here provide clear evidence that archaic and modern humans alike occupied this elevated setting during all of the South African archaeological periods, including the Earlier Stone Age (ESA), the Middle Stone Age (MSA) and the Later Stone Age (LSA). The ESA at Anyskop is characterized by stone handaxes that are scattered across the landscape. While these stone artefacts show no clear focus of human activities, they document the periodic use of this place by archaic humans about 500,000 years ago. The MSA is marked by the more frequent occurrence of Still Bay bifacial tools and Howiesonspoort segments. These types of stone tools were typically used by modern humans for hunting between 80,000 and 55,000 years ago. At Anyskop, the LSA is characterised by numerous, small, microlithic stone tools that also show a focus on hunting activities between 8,000 and 1,000 years ago. In addition, LSA hearths composed of burned stones show clear focal points of human activity where people camped and roasted food.