Research highlight

New lead isoscape map for archaeological provenance studies in Great Britain

A new study aims to determine lead isotope ratios in soil and rock across Great Britain which could inform future archaeological studies about human and animal origins.

28/10/2022
Ancient neolithic stones,West Kennet Long Barrow, Wiltshire. Source: Neil Bussey/istock.
Ancient neolithic stones,West Kennet Long Barrow, Wiltshire. Source: Neil Bussey/istock.

Lead that is naturally present in underlying geology is incorporated in teeth and can be used to inform us of the origins of past humans and animals. Teeth incorporate elements such as carbon, nitrogen and lead from food and water as they form and studying these elements can help us to determine geographical origins and can even tell us more about diet and cultural affinity.

To distinguish the different lead ratios from different parts of the country in teeth samples, a new study, ‘Applying Lead (Pb) isotopes to explore mobility in humans and animals‘, sets out to map lead ratios in the soil and rock across Great Britain. The study uses lead isotope analysis to determine the origins of Neolithic animals, some of the earliest domesticated animals in Great Britain.

Understanding isotopes

Every chemical element, for example carbon or lead, is made up of atoms. Each atom has a nucleus, which contains protons and neutrons. The number of protons in the nucleus in each particular element always stays the same and determines what the element is, but the number of neutrons can vary. Atoms of the same element that have different numbers of neutrons in their nuclei are termed ‘isotopes’. For example, naturally occurring carbon atoms always contain six protons, but may contain six, seven or eight neutrons. This means there are three naturally occurring isotopes of carbon, called carbon-12, carbon-13 and carbon-14.

The problem with lead

Lead is found in low concentrations in rocks and soils all over Great Britain.  Different areas of the country have different lead isotope ratios. Lead isotopes in our natural environment are incorporated into teeth during feeding.  

However, humans have mined lead through time, causing lead pollution that contaminates the signal in teeth. Such studies can therefore only be applied to individuals who predate the onset of mining, or who show no evidence of lead contamination through their measured lead levels.

Speech marks icon

Analysing the lead content of teeth can help constrain the geographical areas in which the tooth formed. This is because animals, including humans, ingest the lead in their food and it is incorporated into their body tissues. To distinguish the different lead ratios from different parts of the country in teeth samples, we first need to establish what the lead ratios in the soil and rock across Great Britain are.

Unfortunately, we can’t take direct measurements of lead in the modern world because of the effect of modern lead pollution, caused by the use of lead in petrol. We therefore need to find alternative methods of defining the distribution of lead isotope compositions.

This was done by using lead ore (predominantly galena) to define ‘domains’ and then to validate these fields to show the geogenic signature was transmitted into the biosphere, using well-provenanced archaeological animals and humans.

Prof Jane Evans, BGS.

The Iapetus Suture

Key to the study is the ability to distinguish between northern and southern British lead sources and this can be achieved because of differences in the underlying geology between these two parts of Great Britain.

There is major geological boundary, called the Iapetus Suture, running between Berwick-upon-Tweed in the east and the Solway Firth in the west. This provides a compositional boundary in lead isotope domains that approximates to the geographical areas of Scotland versus England and Wales.

The Iapetus Suture formed approximately 490 to 400 million years ago, when two tectonic plates called Laurentia and Avalonia came together and closed the Iapetus Ocean, which once separated Scotland from England and Wales. The geology north of this line is very different to the geology to the south and consequently so are the lead isotope domains. 

The Iapetus Suture across Great Britain. BGS © UKRI.
Information icon

The Iapetus Suture across Great Britain. BGS © UKRI.

Expand icon

A new lead ‘isoscape’ for Great Britain

The study, published by PLOS, has produced a lead isoscape map of Great Britain.

A contoured map of (A) 206Pb/204Pb isotope compositions. Superimposed over this contour map is the outcrop area of the Chalk Group. Chalk underlies much of southern Britain but it does not host much lead. Contains OS data © Crown copyright and database rights 2022. BGS © UKRI.
Information icon

A contoured map of (A) 206Pb/204Pb isotope compositions. Superimposed over this contour map is the outcrop area of the Chalk Group. Chalk underlies much of southern Britain but it does not host much lead. Contains OS data © Crown copyright and database rights 2022. BGS © UKRI.

Expand icon

The map shows that there is a strong zonation of the lead isotope domains across the Iapetus Suture and throughout Scotland, which reflects the influence of the very old basement rocks that underlie much of Scotland.

England is dominated by mineralisation that occurred about 300 million years ago (Ma), whilst the ore fields in Wales have an older signature (about 450 Ma) than those in England. Chalk, which is an important lithology in archaeological studies, was superimposed on the mineral map.

Could neolithic animals found in southern Britain have been sourced north of the Iapetus Suture, from Scotland?

The Neolithic henges in southern England, were a focal point for gatherings during Neolithic times (7000 to 2000 BCE). The geographical origin of the people who created and used them is a key question to understanding their construction and use. Neolithic human remains are less common at the henge sites in Great Britain and those that are present tend to have been cremated, which reduces the range of analytical approaches that can be employed.

Isotope studies have focused on the origins of animal remains that have been used as a proxy for the origin of their human ‘owners’. Whilst generating much data on provenance and diet, they could not provide a method of discriminating between origins north and south of the Iapetus Suture.

This study has demonstrated, using lead isotope analysis of Neolithic pig tooth enamel, that these animals originated south of the Iapetus Suture.

About the author

Default-staff-profile
Prof Jane Evans

Research scientist

BGS Keyworth
Find out more

Latest news

A bearded man in dark clothing, a hi-vis vest and blue latex gloves kneels on the ground in front of a fence. He is surrounded by sample pots containing liquids, an oil can, bottles, electrical wires and plastic boxes. He is dipping a sensor into one pot of liquid and looking at an electronic device in his hand.

UK Geoenergy Observatories: time zero for net zero

The BGS-led UK Geoenergy Observatories project is shining a light on the subsurface’s potential to provide geothermal energy.

Show more
The ECORD IODP Expedition 386 Research Team on the helideck of The Chikyu research vessel.

BGS scientists on board research vessel in Japan in major marine research collaboration

Experts from the BGS’s marine team are part of a major international marine research collaboration to understand more about earthquakes associated with the Japan Trench.

Show more
The view down to the Acqua Vergine, a subsurface Roman aqueduct built in 19 BCE. © Tim Kearsey, BGS/UKRI

Building underneath the Colosseum: the importance of urban geology

Tim Kearsey reports on his underground excursion around Rome.

Show more
P577368

Introducing the BGS Debris Flow Susceptibility Model for Great Britain

Debris flows are a landslide hazard of particular concern to transport infrastructure managers and local authorities.

Show more
BGS strategy development public consultation

BGS Strategy: public consultation

We would welcome responses from anyone interested or involved in the geosciences as part of the wider consultation on our new BGS Strategy

Show more
landscape-devon

BGS supports development of a local land-use framework for Devon

The framework will help to identify data improvements to support more joined-up decision making about land use in Devon.

Show more
P608454

Understanding long-term burial of organic carbon deposits

Carbon sequestration is one method of reducing the amount of carbon dioxide in the atmosphere, by capturing and storing it, contributing to climate change reduction.

Show more
Columnar jointing on the side of a steep valley. A human figure stands on top.

Spooky geology

Explore thirteen of our favourite spooky geological hotspots around the UK.

Show more
Deep-sea mining evidence review

Deep-sea mining evidence review published

The deep-sea mining independent evidence review report was commissioned by the UK Government to inform its policy in relation to deep-sea mining.

Show more
Examining the glacial sediments exposed in the cliffs at Happisburgh. Sarah Arkley, BGS © UKRI.

Notes from an applied glacial geology field course in Norfolk

Marine geoscientist Catriona MacDonald and urban geologist Raushan Arnhardt share their experiences from a recent trip to north Norfolk to learn more about glacial geology.

Show more
Ancient neolithic stones,West Kennet Long Barrow, Wiltshire. Source: Neil Bussey/istock.

New lead isoscape map for archaeological provenance studies in Great Britain

A new study aims to determine lead isotope ratios in soil and rock across Great Britain which could inform future archaeological studies about human and animal origins.

Show more
Kibera slum, the largest slum city in Nairobi city, Africa. Source: Africa924/istock

Accumulation of toxic substances in Nairobi’s river sediments

Researchers have warned of the presence of toxic contaminants and untreated wastes accumulating in Nairobi’s Mathare, Ngong and Nairobi rivers.

Show more

Was this page helpful?

  • How can we make this section better?*

  • Please select a reason*

  • How can we make this section better?*