Deep in the heart of the Borneo rainforest lies one of South-east Asia most important natural sites: the of Sarawak, Malaysia. Despite being home to one of the most diverse tropical rainforests on the planet, arguably the world heritage area most astonishing feature lies underground.

The caves of the Gunung Mulu National Park

Under the limestone ridge of Gunung Api lies the extensive Clearwater cave system. At over 260 km in length and with passages often exceeding 30 m in diameter, it is believed to be the world largest cave system by volume, and is a haven for local wildlife.

The nearby Deer Cave is home to an estimated three million wrinkle-lipped bats, which fly out of the cave each evening to feed, creating a stunning visual display. Cave swiftlets also fly many kilometres into the Clearwater cave system to make their nests, which are prized as a local delicacy and used to make bird nest soup. Lying in wait to try and catch them as they fly past are cave racer snakes, whilst an astonishing array of cockroaches, millipedes, crabs, crickets and spiders are sustained by the piles of guano (bat poo) that line the cave floor. The ecosystem featured in a series.

History of the caves

Caves are fantastic repositories of geological and archaeological data, preserving information that would otherwise be lost to surface erosion and degradation. They and the deposits they contain hold clues to past landscape change, allowing us to reconstruct how the Earth’s surface has changed over millennia.

The caves were first explored as part of a Royal Geographical Society expedition in 1978. Working in collaboration with the Sarawak Forestry Corporation and the national park, the has been exploring, surveying and undertaking research in the caves ever since. This includes caving expeditions led by Andrew Eavis, a veteran of the 1978 expedition.

Dating of stalagmites and cave sediments indicates the Mulu caves are up to three million years old. Other analysis of cave stalagmites has yielded a climate record spanning hundreds of thousands of years, whilst volcanic ash provides evidence of a massive volcanic eruption in the Philippines 189 000 years ago. More recent archaeological finds also provide evidence of human activity and burials in some of the caves.

Recent research within this incredible cave system led to a surprising discovery about the formation of the caves within it.

Unusual dissolution

One of the unusual aspects of the Mulu caves is the way the cave passages have been sculpted.  Most caves in the region are formed by the dissolution (dissolving or break down) of limestone by acidic water, primarily from rivers flowing through the cave. The action of flowing water on the limestone rock creates small asymmetrical scoops etched into the passage walls, called scallops. These are preserved on the passage walls even after the formative river has abandoned the passage, as the water finds new, lower routes through the rock. The scallops are of interest to scientists as they can be used to deduce past water flow, providing a record of how water flowed through the caves over time.

In the Clearwater cave system, typical scallops are present in the lower levels of the cave system, close to the present river. However, in the older, higher levels of the cave system, which have long since been abandoned by the river, they are strangely noticeable by their absence, having been dissolved away and replaced by unusual corroded and pitted rock architecture.

The passage walls are frequently eroded into small dissolution pots and coated with a weathered crust: analysis has shown these are composed of calcium phosphate minerals, which is highly unusual in caves. Corroded stalagmites are common, dissolved away like rotten teeth to reveal their internal growth rings. These features suggest some form of atmospheric dissolution of the passage walls and stalagmites has taken place in the time since the passage was abandoned by the underground river.

Comparison with other caves suggests these features are generally restricted to tropical cave systems. One of the key aims of recent Mulu expeditions has been to understand how these features form and why. A team of researchers led by BGS geologist Dr Andrew Farrant, cave microbiologist Prof Hazel Barton (University of Alabama), her PhD student J Max Koether and BGS isotope geochemist Dr Andi Smith set out to investigate what may be happening.

Caving and exploration

Undertaking cave research can be hard work. Sampling trips into a cave system over 250 km long takes time and, in some cases, involved making camp underground. It is hard, sweaty, sometimes muddy work, occasionally requiring ropes to climb up pitches or descend vertical drops. But the rewards are enormous: the caves are spectacular, with stunning formations, huge chambers and amazing biota.

The Clearwater streamway is probably one of the finest cave passages in the world. Not only is there the prospect of new scientific discoveries, but also the chance to explore new cave passages where no human has ever trodden. On one trip, the team crawled through a flat-out squeeze to emerge into an undiscovered chamber over 200 m long, 70 m wide and 50 m high (big enough to hold two Airbus A380 jets) and adorned with 20 m-high stalagmites.

Research

Complex ecosystems are a distinctive feature of tropical caves, driven by the daily input of guano from bats and swiftlets. Bats create large piles of pungent excrement beneath their roosts, whilst the swiftlets’ guano is dispersed more widely, sometimes kilometres into the caves. The teams’ initial hypothesis was that the guano was somehow implicated in creating the unusual dissolution forms and smooth walls seen in the caves. Initial analysis of the guano piles in the caves indicated that they are strongly acidic, comparable to stomach acid or lemon juice, with a pH as low as 1.9. This could account for dissolution beneath the guano pile, but not the pervasive dissolution features seen throughout the caves.

Further work on the microbiology of the guano showed that microbial breakdown of urea (from bats) and uric acid (from birds) generates significant quantities of ammonia and carbon dioxide, which are released into the cave air. Measurable plumes of ammonia can be detected in some caves; could this be responsible for the unusual features?

Attention turned to the weathered ‘paste’ seen on many passage walls. This turned out to be teeming with microbial life, in some places containing a higher microbial cell count than cultured yogurt. Analysis of condensation water droplets on the cave walls revealed extraordinarily high levels of nitrate (up to 7000 mg/l; for comparison, the UK drinking water standard is 150 mg/l), whilst drips feeding the stalagmites had little or no nitrate.

These observations suggest that ammonia released into the cave air by the microbial decay of bat and bird guano adsorbs onto water droplets on the passage walls and stalagmites. Here, microbes use the ammonia as a food source, producing nitrates, nitric oxide, nitrogen dioxide and nitric acid as byproducts. This acid dissolves the passage walls and stalagmites, removing the original dissolutional scallops and replacing them with a suite of biogenic dissolution features. It is estimated that, in some places, several metres of dissolution have occurred in just a few tens of thousands of years: geologically speaking, this is a very short time period.

Further work is ongoing to learn more about the microbial processes that occur within the guano and on the cave walls. The discovery of this novel mechanism of cave development has significant implications, such as how we interpret past environments from caves, the preservation of cave art, and the impact of this acidic environment on ropes and other caving equipment.

The great thing about the Mulu Caves Project expeditions is they have enabled us not just to explore new caves, but to do some amazing science too. One thing is clear from our work in the caves; the surface and underground environments are inextricably linked. There is much we still have to discover and one wonders what other secrets are waiting to be discovered beneath Gunung Api…

Publication

Our research has been recently published in the journal Geomorphology.

Farrant, A R, Koether, J M, Barton, H A, Lauritzen, S E, Pennos, C, Smith, A C, White, J, McLeod, A, and Eavis, A J. 2025. . Geomorphology, Vol. 483, 109822. DOI: https://doi.org/10.1016/j.geomorph.2025.109822

Thanks                 

Thanks go to Andrew Eavis and members of the Mulu Caves Project, the Sarawak Forestry Corporation and the Gunung Mulu National Park management and staff, without whom this work would not have been possible. Part of the research was funded by a NEIF steering committee grant to Andi Smith.

About the author

This project is investigating how the phosphorus content and phosphate oxygen isotope (δ¹⁸O-PO₄) signatures in sediment cores change over time, to establish the value of this proxy for environmental reconstruction research. The research builds on a fellowship project between BGS and Loughborough University with Dr Savannah Worne, and is part of an ENVISION DTP PhD project at Lancaster University. 

The importance of phosphate oxygen isotopes

Normally, the bonds between phosphorus and oxygen in phosphate (PO₄^3-) are very stable and don’t break down easily under typical conditions on Earth. This means that oxygen isotopes within PO₄^3- remain unchanged, unless biological processes are involved. However, certain enzyme-driven reactions, both inside and outside cells, can break these bonds and allow oxygen isotopes to exchange with the surrounding water. This has led to the discovery of a temperature-dependent balance between water and PO₄^3- cycling, which can help scientists better understand how PO₄^3- is processed by living organisms.

Recent advances in analysing δ¹⁸O-PO₄ have made it easier to use them as indicators of biological cycling of inorganic PO₄^3-. Using modern water oxygen isotope (δ¹⁸O-H₂O) data, we can calculate the temperature-dependent equilibrium value for δ¹⁸O-PO₄, which reflects the complete biological turnover of phosphate.   

Applying this method to lake sediments is a new and innovative technique that builds on current soil methodologies and allows for past studies of phosphorus cycling. We expect that the δ¹⁸O-PO₄ value in the sediments will reflect the level of biological processing at the time of deposition, with values moving closer to equilibrium when PO₄^3- is utilised more. To date, there have only been rare applications of δ¹⁸O-PO₄ to lake sediments, with no prior applications to a lake sediment core. In part, this reflects the unknown preservation of the δ¹⁸O-PO₄ signature within the core over time.

Rutland Water

Rutland Water is one of the largest artificial reservoirs in Europe, located in the East Midlands. Spanning approximately 4200 acres, it was constructed in the 1970s to ensure a reliable water supply for the surrounding region. Over the years, the reservoir has evolved into a vital site for drinking water supply, wildlife conservation and recreational activities, drawing nature enthusiasts and visitors alike.  

A key part of the site is the Rutland Water Nature Reserve, which is composed of woods, grassland and meadows as well as eight shallow water lagoons, covering around 1000 hectares. Managed by Anglian Water and the Leicestershire and Rutland Wildlife Trust, this area of Rutland is internationally renowned for its rich biodiversity, with wetlands, woodlands and open waters providing habitats for a variety of wildlife species, including the famous ospreys. Our research aligns directly with the water quality management goals of the site, to ensure the ongoing sustainability of this unique environment.

Sampling and research activities

In collaboration with the Leicestershire and Rutland Wildlife Trust, we collected three sediment cores from a nutrient-rich lagoon in the Rutland Water Nature Reserve to study how phosphorus levels and the PO₄^3- oxygen values in lake sediments change over time.

The first core was cut into thin layers and analysed immediately to give us a baseline of current conditions. The other two cores were stored under different conditions for six months to see how much the phosphorus concentrations and isotope values might change over time. One core was sliced into layers before storage (exposing it to air), while the other was kept intact in its tube, mimicking in-lake preservation conditions. These two cores were treated with isotopically enriched water before storage, with the intention that the isotope label would appear in future data sets if biological activity persisted, even at depth. 

Preliminary discoveries

So far, the analysis of the first core has provided useful baseline results, by identifying four different pools that phosphorus is bound to: bioavailable, microbial, metal-bound and non-labile. The results hint at the varying stability of these phosphorus forms within the sediments.  This analysis also gives us an opportunity to improve our analytical methods.

Findings from the stored cores will be key to our understanding of how phosphorus in sediments behaves and changes over time, offering insights into nutrient cycling at Rutland Water. All of this data will be part of my ongoing PhD thesis.

About the author

Christopher Bengt is a PhD student enrolled at Lancaster University. His PhD is funded through the Envision Doctoral Training Partnership and the BGS University Funding Initiative.

Bladder cancer incidence ranks ninth out of all cancers worldwide, with over 600��000 cases and 200��000 deaths annually. In the UK, these numbers are 10��000 and 5000, respectively, with only 46��per cent of patients surviving for around 10 years. Almost half of bladder cancers are diagnosed at stages 3 and 4, with poorer prognosis for these later stages.

The ‘gold standard’ diagnostic procedure for bladder cancer is cystoscopy. As well as being an invasive test involving the insertion of a camera into the bladder, it is more costly in the UK than anywhere else in Europe. Currently, the UK has the third-highest bladder cancer healthcare costs per prevalent case in the world.

A research team that includes chemical analysts from BGS has been awarded a grant from Cancer Research UK to test the performance of a urine-based liquid biopsy test for the disease. To date, due to their poor performance and low cost-effectiveness, commercially available urine biomarkers have not been recommended by urological societies for the screening or management of bladder cancer.

The new test, which works by searching for genetic mutations known to occur in a large proportion of bladder cancers, was initially developed under the leadership of Dr Florence Le Calvez-Kelm at the . It has already shown early success in the accuracy of detecting the disease in European populations. In this new research project, called ‘UroScan’, the team will look at 100 bladder cancer cases and the same number of healthy controls, who will all undergo the test to assess its accuracy.

This is the first time the test will be used in a population at high risk of arsenic exposure in Bangladesh. Arsenic is an established bladder carcinogen and affects people in the UK as well, particularly those using an untreated private drinking water supply. Participants’ urine samples will undergo arsenic measurement by Dr Michael Watts and his team of analytical chemists at BGS.

The development of accurate, non-invasive early detection methods are a critical step to reducing bladder cancer burden and diagnostic waiting times, particularly when considered against pre- and post-pandemic pressures on the NHS and its growing backlog of cancer patients.

Dr Dan Middleton, Cancer Epidemiology Group, Centre for Public Health at Queen University Belfast.

Investigating the potential of early detection biomarkers for bladder cancer in an understudied population of Bangladesh is pivotal in the context of reducing the burden of cancer in this region and beyond.

Dr Ismail Hosen, University of Dhaka, joint lead researcher.

This project builds on a collaboration of more than 10 years of refining the methodologies to better understand the potential exposure to arsenic in the environment and to inform the consequences for human health to stimulate approaches to reduce exposure.

Dr Michael Watts, head of BGS Inorganic Geochemistry.

The researchers have recently started the study and the first results are expected in 2025, before hopefully scaling up to a larger, UK population-based study that will incorporate exposure to arsenic in highly mineralised locations in rural areas, where private water supplies are most common.

My name is Christopher Bengt and I am first-year PhD student enrolled at Lancaster University and I am being hosted at the BGS by the Stable Isotope Facility. My PhD is funded through the and the 51���� University Funding Initiative. My research aims to understand fundamental questions about how tropical forest composition, structure and flowering dynamics are affected by the concentrations of essential nutrients, importantly phosphorus, in the soil. 

My previous research 

Prior to taking this post, I completed my master degree (MRes) in biological science at Birkbeck, University of London, where I studied the extraction of DNA from archaeological animal bones. This work involved using a number of analytical methods to assess the level of damage to the bones, indicating the extent of preservation of ancient DNA. Whilst studying, I also worked on immune response to vaccines and infectious diseases as a laboratory technician at the World Health Organisation Pneumococcal Serology Reference Laboratory at University College, London. All these skills stand me in good stead for my PhD, which will have significant laboratory and fieldwork requirements.  

Tropical rainforests 

Tropical rainforests are the oldest living and most complex ecosystems on Earth, with evidence from fossils and pollen dating back 70 million years. Being in the tropics, the rainforests have a stable climate consisting of warm temperatures, high precipitation levels and high levels of solar irradiation, providing essential conditions for highly productive forests. The stable climate, abundant resources and millions of years of evolution mean biodiversity in tropical rainforests has flourished, resulting in countless species with specialised adaptations.  

The effect of volcanoes on tropical ecosystems 

Unexpectedly for such diverse and productive ecosystems, rainforest soils are often of poor quality, with low concentrations of nutrients including carbon, nitrogen, potassium, and phosphorus. However, in areas such as the Philippines (my study area), volcanic eruptions can deposit nutrient-rich ash directly into the tropical rainforest environment. Volcanic ash is composed of fine rock particles that can be expelled and then deposited over vast areas, many kilometres from the original site of eruption. These particles contain essential nutrients such as potassium and phosphorus, and it is hypothesised that these may be critical for soil enrichment.  

Whilst volcanic eruptions can pose an immediate threat to local ecosystems, the aftermath may help foster these fertile environments. The relationship between volcanoes and nutrient-rich soils underscores the dual nature of these natural phenomena that are both destructive and transformative.  

Past records of climate 

To better understand the relationship between volcanoes and tropical ecosystems, we must explore past records of volcanic activity and forest productivity. These are often best found within lake sediment archives.  

Lakes serve as repositories of environmental history through the sediments that accumulate at their bottoms. The sediments are composed of organic and inorganic materials and encapsulate a wealth of information, telling us about crucial nutrients (including phosphorus) and serving as archives of ecological changes. My project will analyse both the nutrient makeup of the lake sediments and the ancient DNA preserved within them. In combination, these records will allow us to investigate the links between nutrient dynamics, ecosystem productivity and plant and tree diversity.  

For my project, I will undertake a fieldtrip to Lake Bulusan at Mount Bulusan, one of the most active volcanoes in the Philippines, which is surrounded by rainforest. Cores of the sediment from the lake will be brought back to the UK to interrogate the geochemical signatures trapped within them. The sediment cores will also be sent to the University of Copenhagen, Denmark, to extract and analyse modern and ancient DNA.  

These records should tell us more about how climate, volcanic activity and biological history are linked throughout the last 2000 years. This multiproxy approach will uncover critical information regarding the modern phosphorus cycle and soil limitations, as well as the true impact volcanic events have had on the phosphorus cycle in the palaeorecord and, in turn, the development and flowering of the surrounding tropical forest. The findings could potentially offer a ‘step change’ in our understanding of tropical forest development in volcanically active regions.  

About the author

Christopher Bengt is a first-year PhD student enrolled at Lancaster University. His PhD is funded through the and the 51���� University Funding Initiative.

A team of isotope scientists from BGS, along with Cardiff University, has led research that has developed a new analytical method to identify archaeological remains of humans and animals that once inhabited wetlands. The method provides an additional tool for archaeologists to explore human and animal mobility in the past.

Identifying human and animal movement has long been an important pursuit in archaeology. Isotope analysis provides direct data for this and is helpful in identifying non-local individuals and patterns of migration.

Our aim was to test the hypothesis that certain underlying rock types will produce low sulphur (sulfur; S) isotope values, which are transferred through the food chain and could therefore provide a means of identifying humans and animals raised in wetlands in the past.

Angela Lamb, BGS Isotope Geochemist.

The new research explored the potential of previously undiagnostic low, often negative, S-isotope values to identify wetland dwellers. This was carried out by testing the hypothesis that impervious clays, which often support wetlands, will produce low S-isotope values due to both the underlying substrate and redox conditions.

Collecting samples

To characterise the modern S-isotope biogeography of typical wetland environments, the researchers collected and analysed 58 modern plant samples taken from areas overlying Jurassic rocks in southern England. The sampling targeted archaeologically important areas of the Somerset Levels and the Cambridgeshire Fens. S-isotope ratios were also extracted from the bone collagen of 65 faunal fossil samples from archaeological sites in both regions and analysed to compare with modern data and test if this relationship held for archaeological samples. To understand if the plant signals were transferred up the food chain to the fauna, S-isotopes in modern bone collagen, extracted from nine farm animals raised in these areas, were also analysed.

An additional tool for archaeologists

Of the samples tested, 60 per cent gave a value below zero, with the modern plant datasets giving more negative values for the eastern regions of Cambridgeshire relative to Oxfordshire and Somerset. The plants showed a correlation between S-isotope composition and altitude, which supports the idea that low-lying wetlands supply the most negative values into the environment.

These results support the interpretation that relatively low or negative S-isotope values are indicative of vegetation and wildlife growing and grazing on wetland regions underlain by Jurassic clays. Data from this study formed part of a new BGS isotope domain map (see Figure 1).

Further work is needed to resolve regional differences in the altitude below which low S-isotope values occur and to understand S-isotope variability in higher altitude locations on the Jurassic clay, but this is a step forward in our understanding and therefore the application of low S- isotope ratios.

Angela Lamb

As a result, ancient humans and animals from wetlands, or that acquired their food from wetlands, may be identified using primary analytical methods. This provides an additional tool for archaeologists to explore animal management and human and animal mobility in the past.

More information

Read the research:

Human activity has led to excess phosphorus concentrations and the continued over-enrichment of coastal and fresh waters across the United States. Alongside colleagues from Union College in New York and Lancaster University, BGS scientists are researching the biogeochemical cycling (how specific chemicals cycle through the biological and geological components of the Earth) of .

What is eutrophication?

Eutrophication is the process by which water becomes progressively enriched with minerals and nutrients, for example phosphorus and nitrogen. It can affect both coastal and fresh waters and can be caused by excess phosphorus entering the water system. Natural eutrophication is a very slow process, but it can occur much more rapidly when pollution accumulates from human sources such as sewage and fertilisers. Eutrophication can cause harmful algal blooms, leading to oxygen depletion in the water and damage to local ecosystems.

Previous and new research

This new research follows on from studies initially undertaken in the UK in 2016 (Gooddy et al., 2015; Ascott et al., 2016) that looked at mains water leakage and the associated inputs of phosphate that this causes. However, these studies only considered mains water leakage: the new study employs an innovative way of determining previously unaccounted-for phosphorus sources at a much bigger scale. It estimates, for the first time, the amount of phosphorus that enters the environment from the US public water supply.

Phosphorus in US public water supplies

Public water systems across the United States widely dose water with phosphate (PO₄) to control the corrosion of lead and copper within water distribution networks. When pipes leak or people water their lawns, this phosphate enters the environment and can find its way into rivers and groundwater. About 5 to 17 per cent of this phosphate-dosed water leaks out of water mains, whilst 5 to 21 per cent is used outdoors. In some parts of the US, the amount of phosphorus entering the environment from the water supply exceeds that coming from point sources like wastewater treatment plants, or from agriculture and fertilisers.

Developing a more effective phosphorus management policy requires a comprehensive understanding of phosphorus sources and routes into the environment, which are known as fluxes. These fluxes should be considered in relation to other sources of phosphorus in the aquatic environment (Gooddy et al., 2017) and can inform localised phosphorus management practices.

Future work

The next step is to look at carbon cycling and greenhouse gas emissions from water use in the US. A sister study, which was published by the same authors in 2022, looked at how water supply processes are responsible for significant nitrogen fluxes (Flint et al., 2022).

Researchers and funding

51���� is the lead on this research with PhD candidate Elizabeth Flint supervised by Dr Matthew Ascott and Prof Daren Gooddy. There has also been input to the work from Dr Mason Stahl from Union College, NY, USA and Dr Ben Surridge at Lancaster University, UK.

This work has been funded through ENVISION DTP with supervisor support provided through the BGS BUFI programme and National Capability funding through Groundwater Processes.

Further reading

References

Believe it or not, bears were a common sight in England in the early modern period (c. AD1549 – 1700). They were imported for the cruel sport of animal baiting, where dogs were made to fight other animals for human entertainment. In order for baiting to happen, many bears and dogs were brought together. During excavations, our project partners, the (MOLA), found the bones of these animals in Southwark on the south bank of the Thames.

Our research project, ‘: animal baiting in early modern England’ funded by the (AHRC), is looking at this understudied subject and the remains of the animals themselves. References to baiting are found throughout Shakespeare plays and Dr Callan Davies on our project has drawn together over 1200 archival records on the topic. Baiting was clearly big business, with the Masters of the King Game (appointed by the monarch of the day) overseeing the ownership and licenses of all bears in the country.  

In collaboration with Dr Angela Lamb at BGS, we are examining the diets of the animals found at Bankside, as archival records at Dulwich College suggest the . Stable isotope analysis of nitrogen and carbon in their bone collagen will help us to understand what the bears were eating at the time, as animals fed on meat will have a higher nitrogen isotope value than those fed on bread. This will tell us about how they were cared for and give us an insight into their daily lives. The diet of bears is also important as it determines . We are also investigating what the dogs were being fed. Both bears and dogs are omnivorous, so they can eat a wide variety of foods.

Dr Lizzie Wright and Prof Hannah O’Regan from the at the University of Nottingham prepared over 100 collagen samples from dogs, bears, cattle and horses from the collections at MOLA and the Museum of London. After 14 months, the final results of our analyses have just come off the mass spectrometer, so we expect to be able to answer our queries about diet in the very near future. Keep an eye out for research updates on the Box office bears website as the project progresses and watch out for the exhibition ‘’ opening at the University of Nottingham Archaeology Museum at Lakeside in July 2023!

Acknowledgements

Thank you to MOLA and the Museum of London for permission to study and take samples of the bones. Thank you to Holly Miller for training and advice on collagen extraction. Huge thanks to the AHRC for funding our work.

About the authors

, professor of archaeology and palaeoecology, University of Nottingham

Dr Lizzie Wright, research fellow archaeozoology, University of Nottingham

Domesticated animals were an important part of prehistoric communities following their introduction to Britain after about 4000 BCE. Analysis of their remains can cast light on their movement and offer a proxy for the day-to-day mobility of their human companions.

Why study mobility?

Studying mobility at smaller scales helps to illustrate our understanding of life in past societies and the landscapes in which they lived. This is the essence of my PhD research, which uses isotope analysis of bones and teeth of cattle, sheep and pigs to explore their diet, from which it is possible to understand more about their husbandry regime and use of landscape resources for grazing.

Field locations

The Lincolnshire fenlands are rich in archaeological sites and my project is looking at two contrasting locations excavated by local units. Network Archaeology in Lincoln uncovered material at sites along the route of the Lincoln Eastern Bypass road, while the Cambridge Archaeological Unit (CAU) holds samples excavated from sites now lost to gravel quarrying to the east of Langtoft, near Peterborough. These represent two different types of grazing: the site near Lincoln is more of a freshwater environment, whilst the one near Langtoft was close to the fen edge and the area subject to marine incursions in prehistory.

The faunal (animal) material from both sites is broadly contemporary, dating to the Middle Bronze Age (around 1500 BCE), and lets us investigate whether animals at the Langtoft site may have been grazed on the fen-edge saltmarshes in summer, whilst the Lincoln animals were further inland.

Isotope analysis at NEIF

������� (NEIF) at BGS Keyworth has funded my isotope analysis of animal bones and teeth from Lincoln and Langtoft through a collaborative project entitled ‘When did the cows come home?’. Prof Hannah O’Regan from the University of Nottingham is the principal investigator and BGS Dr Angela Lamb and Prof Jane Evans are co-investigators. The analysis will include simultaneously determining stable isotopes of carbon, nitrogen and sulphur in each sample using the laboratory Thermo Fisher IsoLink elemental analyser.

Soil samples

The isotope analyses of faunal bones and teeth are complemented by the analysis of soil samples collected by CAU at 2 m intervals along eight transects. The transects cross the ditch features of enclosures and a proposed droveway, along which animals may have been moved. Laboratory-based X-ray fluorescence (XRF) spectrometry from the School of Geography at the University of Nottingham is providing data on concentrations of elements, from sodium to radium.

Once complete, the data should allow the creation of an interpolated map showing ‘hot spots’ of elements associated with the presence of animals, such as phosphorus from the phosphates present in their dung. Hopefully, this should reveal concentrations in areas associated with their penning as well as movement along the droveway to and from the fen edge.

Results so far and continuing work

A selection of bones from both sites has been analysed. The bones have shown unexpectedly high concentrations of sulphur, which are a feature of some marine estuarine environments. To explore this further, we are processing some samples obtained from the banks of the Thames at Bankside, dating from the 17th to 19th centuries, and at Wapping, thought to date from the Tudor period. This will allow us to assess if the sulphur isotope signal is contaminated.

The next stage is to sample the dentine from the cattle and sheep teeth. Hopefully multiple, incremental samples in teeth from Langtoft will show oscillating levels of sulphur isotope values, with higher values obtained from summer grazing on the fen-edge saltmarshes and lower values from wintering on drier land. The teeth from the freshwater environment near Lincoln should not exhibit these changes.

Bronze Age Forum meeting

The project was presented at the Bronze Age Forum in Cambridge in November 2022, where it was awarded the Prehistoric Society prize for best poster contribution.

Acknowledgements

Thanks go to:

• Diana Fernandes and colleagues at Network Archaeology in Lincoln
• Dr Marcus Brittain, Dr Emily Banfield and Vida Rajkovača at CAU
• Lara Maiklem for the Thames bone samples

Funding

Funding was received from the Arts and Humanities Research Council (M4C) and ������� (NEIF) at BGS Keyworth.

About the author

David Osborne is a PhD student at the Department of Classics and Archaeology, University of Nottingham.