Science may hold the clue to an ancient riddle

28 April 2006

The combination of an international project to enhance carbon dating from archaeological samples, and the remains of an olive tree, may hold part of the clue to resolving an age-old archaeological controversy stemming from the times of ancient Greece.

Photograph: Collapsed main staircase in Building Delta-North at Akrotiri, Santorini. Attributed to seismic activity shortly before the eruption.

A team headed by Professor Sturt Manning of Cornell University, who is also visiting professor at Reading University, along with colleagues Christopher Bronk Ramsey and Thomas Higham from Oxford University, have used funding from the Natural Environment Research Council (NERC) to date the period.

Their findings, published in the journal Science today, suggest that the dates of the Aegean cultures may be earlier than previously thought.

Archaeologists have previously used similarities amongst artefacts to date the civilisations, but uncertainty about radiocarbon dating was enough to leave experts debating the dates.

Professor Manning's team have created one of largest sets of focused radiocarbon data ever. With analysis spanning a 300 year period, it has been possible to suggest new chronology for the Aegean late Bronze Age 1700-1400 BC.

By analysing 127 samples taken from sites in Santorini, Crete, Rhodes and Turkey, they have pointed to the Aegean culture being older than previously suggested - with links to previous Egyptian civilisations - over whose chronology there is less uncertainty.

In an attempt to address some of the questions over radio carbon dating calibration, such as contamination, location, and atmospheric factors, the team used a sophisticated statistical analysis and far wider sample base. The project also used more than one laboratory to further limit the risks of error in setting the carbon dates.

As an example, the team can define the age of charcoal from a very small segment of an oak chair that was buried for more than 3,600 years, to within a date range of 27 years with 95 per cent confidence.

Photograph: Reconstruction of LMI country house at Myrtos-Pyrgos, Crete (excavated under the direction of Gerald Cadogan), by Jeff Clarke.

The two sets of findings mean a shift of the dates for the Aegean civilisation and its cultures - such as the buried town of Akrotiri on Santorini, the 'Pompeii' of the Aegean - by about 100 years earlier.

Professor Manning said, "Our findings also imply that some previously hypothesized dates and associations for the Santorini eruption around 1650 or 1645 BC are now not so likely, and new efforts need to be directed at the ice-core and tree-ring records if a specific date is to be achieved. Together the two studies offer a very solid basis to a re-dating of this period. This has major ramifications for the archaeology, art-history and other records for the region."

"If the findings are accepted, then the earlier chronology would frame a different context, and a longer era, for the very genesis of Western civilisation. The seventeenth century BC may become a very important period," he added.

Further information

Professor Sturt Manning
Dept of Classics, Cornell University
Ithaca, New York, USA
Tel: 0207 603 9183 (UK contact)
Mob: 07860 935 936

Christopher Bronk Ramsey
Oxford University
Tel: 01865 285215

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411727 or 411561
Mob: 07917 086369 or 557215

Notes

1. This study was funded by a NERC grant and by NERC's funding of the Oxford Radiocarbon Accelerator Unit, and through the support of SCIEM2000 - a special research programme of the Austrian Academy. The International partners in the project are the Vienna Environmental Research Accelerator and the Heidelberg Radiocarbon Laboratory.

2. The work of Manning and colleagues was conducted at Oxford University as part of a NERC funded project. Both the British and the Danish-German papers make use of methods of statistical analysis developed at Oxford by Christopher Bronk Ramsey, Director of the NERC supported Oxford Radio Carbon Accelerator Unit. This work underline the important part that Oxford and NERC are playing in the resolution of chronological issues in archaeology and environmental science.

3. Sturt Manning, formerly at the University of Reading, and still a visiting professor in the School of Human and Environmental Sciences, is now a Professor in the Department of Classics, Cornell University. USA. He is also incoming Director of the Malcolm and Carolyn Wiener Laboratory for Aegean and near Eastern Dendrochronology at Cornell.

4. NERC is one of the UK's research councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind, such as global warming, renewable energy and sustainable economic development.

Press release: 25/06

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Science explains ancient copper artifacts

Public release date: 13-Jun-2011
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Contact: Erin White
ewhite@northwestern.edu
847-491-4888
Northwestern University

EVANSTON, Ill. --- Northwestern University researchers ditched many of their high-tech tools and turned to large stones, fire and some old-fashioned elbow grease to recreate techniques used by Native American coppersmiths who lived more than 600 years ago.

This prehistoric approach to metalworking was part of a metallurgical analysis of copper artifacts left behind by the Mississippians of the Cahokia Mounds, who lived in southeastern Illinois from 700 until 1400 A.D. The study was published in the Journal of Archaeological Science in May.

The researchers were able to identify how the coppersmiths of Cahokia likely set up their workshop and the methods and tools used to work copper nuggets into sacred jewelry, headdresses, breastplates and other regalia.

"Metals store clues within their structure that can help explain how they were processed," said David Dunand, the James N. and Margie M. Krebs Professor of materials science and engineering at Northwestern's McCormick School of Engineering and Applied Science and co-author of the paper. "We were lucky enough to analyze small, discarded pieces of copper found on the ground of the excavated 'copper workshop house' in Cahokia and determine how the metal was worked by the Cahokians."

Two materials science and engineering students conducted much of the research. Matt Chastain, a Northwestern undergraduate at the time of the study, worked alongside Alix Deymier-Black, a graduate student in the materials science and engineering department. Chastain, first author of the paper, undertook the metallurgical analysis of the samples, supplied from ongoing excavations at Mound 34 in Cahokia. Chastain followed up his analysis by volunteering at the excavation site.

"We cut through some samples of the copper pieces and polished them to look at the grain structures of the copper with a microscope," said Deymier-Black, second author of the paper. "From the size, shape and features of the grains inside the copper, we determined that the coppersmiths were likely hammering the copper, probably with a heavy rock, then putting the copper in the hot coals of a wood fire for five to 10 minutes to soften it and repeating the cycle until they had created a thin sheet of copper. "

After using basic metallurgical science to better understand the methods the Cahokians used to create copper sheets, Deymier-Black and Chastain recreated the metalworking process in the lab with natural copper nuggets, fire and a heavy stone ---pounding and heating the copper into thin sheets.

The researchers also tested theories that some archeologists had made about the coppersmiths' techniques. One idea was that they made large copper pieces, like ceremonial breastplates, by "laminating" sheets of copper together through a hammering technique. Deymier-Black said that the lamination could not be reproduced, even with much greater weights achievable with a modern press. The other hypothesis, that the Cahokians used copper knobs or copper rivets and other mechanical devices to secure sheets of copper together, seems more likely.

Another puzzle was how the Cahokians cut the hammered sheets of copper into regular shapes. The researchers cut replicated hammered sheets by four different methods: grinding an embossed ridge, shearing with scissors, hammering against a sharp corner, and bending the sheet back and forth. Only the bent edge looked similar to the edge of the historical artifacts, indicating that the Cahokians most likely used that method to cut copper.

Scientific insight into the process used to create the sacred copper artifacts of Cahokian people is helpful to James Brown, professor of anthropology at Northwestern Weinberg College of Arts and Sciences and John E. Kelly, professor of anthropology at Washington University in St. Louis. The two researchers, co-authors on the study, are credited with pinpointing the location of the copper workshop at Cahokia.

"I'm delighted that through the scientific process we were able to confirm some of the techniques and end some disputes about how the copper artifacts were made," said Brown, also an international expert on Native American archaeology. "This study gives some of the real details, so that an observer can imagine how it was done and could possibly hook onto other kinds of observations about the people of Cahokia."

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