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The Parts of the Sum

A visit with Michael Glascock, Senior Research Scientist and Research Assistant Prof of Nuclear Engineering, Research Reactor

By Kyle Burton
Published: - Topics: physics archaeology trade routes obsidian limestone

Dr. Michael Glascock defines archaeometry as the combination of several scientific practices—“chemistry, physics, biology, engineering, statistics, etc.”—used to analyze manmade and natural artifacts. Dr. Glascock is a research professor with the Archeometry Lab at the MU Research Reactor, where he tracks trade routes and preferred materials of ancient peoples. He has lectured around the world and promotes the philosophy he applies to his work here: archaeometry is, by definition, a cooperative field, and Glascock believes in the collaborative process. He says, “It’s really the team of archaeologists plus physicists and chemists getting together—they can produce a really good product.” His hope is that this successful approach can lend itself to other labs.

Glascock and team make use of a unique combination of resources available on the MU campus. The research reactor powers a diverse set of analytical techniques: neutron activation analysis, x-ray fluorescence, and inductively coupled plasma mass spectrometry. “I’m pretty sure we’re the only place in the world that has all three of these techniques,” Glascock notes.

The primary technique is neutron activation analysis; the sample is irradiated and the measured emissions indicate the sample’s composition. Secondly, x-ray fluorescence uses reflected x- and gamma rays to register a material’s composition. Finally, inductively coupled plasma mass spectrometry, the most powerful but also most invasive and expensive technique, ionizes the sample in order to analyze its makeup.

Each fingerprinting (matching an artifact with its material’s source location) allows Glascock and team to pinpoint the origins of an artifact separated from its source and then interpret the story of that separation. For example, he recently worked with a Chinese scientist characterizing samples from Longmen Grottoes. The cave, a member of UNESCO’s World Heritage List, contains upwards of 100,000 immaculate Buddhist statues sculpted from the cave walls—which, over the years, have been pilfered. Glascock discovered three distinct limestone compositions within the caves, which, with the forthcoming publication on these findings, will make it easier for archaeologists and anthropologists to identify artifacts belonging to one of mankind’s grand artistic achievements.

Glascock and his team primarily analyze limestone, flint and pottery—pottery being about 70 percent of their samples: “Ceramics are found everywhere in the world. People have been making pottery for at least 20,000 years,” says Glascock. In addition, he notes perhaps the most useful material they handle is obsidian, a glassy rock formed by volcanic eruptions. Its uniquely homogenized composition makes it the easiest material for Glascock to track. He points out, “Artifacts of obsidian have been found here in Missouri, Ohio, even all the way out to the east coast. So how did they get there? They got there by people trading or exchanging them, or handing it down the line.” The obsidian’s composition matches its source almost identically, pinpointing the region where an artifact originated. He and his team have developed a catalogue of over 1,000 obsidian sources from areas such as Central and South America, Africa, the Mediterranean, Russia, and western Asia.

The volume, variety, and quality of archeological data collected at a research reactor contribute significantly to the field; unfortunately, when a reactor closes down, that data can be lost. Rescuing data from closed-down labs is presently occupying a good deal of Glascock’s resources. Semi-humorously Glascock says, “It’s almost an archeological study of its own.” Sometimes the data is easily accessible. Other times, as with the University of California-Berkley lab Glascock recently added to his team’s database, data is scattered on notecards or computer printouts.

Acquiring and incorporating this outside data require painstaking work; his team enters the data, rechecking each individual input, oftentimes finding gaps in the information itself. “In the best case we’re working on,” Glascock says, “we’ve recovered about 70 percent of the original data that was collected over about a 25 year period. We feel pretty good about that.” In those best cases, Glascock’s team can recover decades’ worth of data in a matter of months.

Much of the work behind social, cultural, or historical cataloguing is the study of movement, physical or abstract. Glascock his team address how centuries-old artifacts traveled thousands of miles and for what purpose?—if traded, between whom?—why would a particular people value one product over another? By Dr. Glascock’s estimation, he and his crew have analyzed more than 100,000 samples and generated nearly 500 publications in the past 25 years. Those achievements are indicative of his philosophy, and exactly why he encourages other scientists to embrace collaboration.