by Amy Stone, University of Sheffield
May 31, 2013 (TSR) – Magnetic analysis lets archaeologists match obsidian artifacts from Syria to the specific quarry—not just the volcano—of origin.
While at the University of Sheffield from 1965 until 1972, Professor Lord Colin Renfrew developed a technique that matched stone tools made of obsidian, naturally occurring glass, to their volcanic origins based on their chemical fingerprints.
Matching artifacts to specific volcanoes was a significant leap forward in understanding trade, contact, and cultural change in the ancient world.
Nearly 50 years later, Ellery Frahm’s work is the next major advance in obsidian sourcing. Previously it was only possible to match an artifact to a particular volcano or lava flow, sometimes covering dozens of chemically uniform square kilometers.
Frahm’s new approach builds on traditional methods with additional magnetic analyses. The magnetic properties of obsidian vary on the scale of meters, not kilometers, enabling researchers to match an artifact to a particular quarry at the volcano.
The result is much greater specificity of an artifact’s origin, enabling human behaviors in the past to be reconstructed with greater spatial resolution than previously possible.
“Sourcing artifacts in this way gives us a sharper picture of the past,” explains Frahm. “We have already used this approach to show how obsidian was collected from certain quarries at volcanoes and how ancient quarrying locations change over time.
“This approach provides a deeper insight into our understanding of past human behavior and will hopefully enhance research into how different groups managed natural resources linked to their economies.”
Indeed, one of the most important aspects of the study for Frahm and his collaborator, Joshua Feinberg at the University of Minnesota, was the simplicity of the approach and how widely applicable it will be. Their findings are published in the Journal of Archaeological Science.
“Our magnetic tests were chosen in part for their simplicity so that most rock magnetism laboratories could take the necessary measurements and apply this new approach worldwide. We did not want to develop a technique that could only be done in one or two laboratories in the world. It was important the approach be accessible, making it as ‘open source’ as possible.”
Development of this approach partly depended on the sheer quantities of specimens and artifacts studied, “This study involved more magnetic measurements of obsidian than all previously published studies combined,” explains Frahm. “The resulting picture revealed how to identify quarries of particular importance to Mesopotamian peoples, and it helps us to piece together their cultural significance.”
Heritage in danger
The cultural significance of artifacts to Syria’s heritage, which is under threat due to the current conflict, is an important part of Frahm’s research. “During my fieldwork in Syria, I identified some spectacular artifacts that should be curated and displayed to the Syrian public at the Deir ez-Zor archaeological museum.
“Unfortunately, Deir ez-Zor has been a center of fighting since summer 2011. The last time I had an update, the museum had become a stronghold for the Syrian military, even with snipers on the roof, and it appears that when they pulled out last fall, the museum was essentially trashed.
“This has a doubly damaging effect on the country. Not only do many Syrians see archaeological sites and artifacts as part of their heritage, but also archaeological excavations put money into the local economy and employ local workers, helping people in rural villages make ends meet. Protecting Syrian heritage throughout this terrible conflict is an issue that needs attention from people who are in a position to help.”