science

Archaeological finds aren’t always unearthed from the ground or recovered from caves and catacombs. Sometimes, they basically fall from the sky.

When a coffin crashed down from a cliff near the Baltic Sea near the village of Bagicz, Poland, in 1899, it was (unsurprisingly) the last thing anyone expected. Made from the hollowed trunk of an oak tree and exceptionally preserved, it protected the bones of a young woman from the ancient Wielbark culture who was thought at the time to have likely been a member of the social elite. She was buried with a bronze fibula, a necklace of glass and amber beads, a brooch, and bronze bar bracelets; was laying on a cowhide; and had a wooden stool at her feet.

Eventually, both she and her coffin found a new resting place in a museum, and were almost forgotten until the 1980s, when archaeologists rediscovered the partial skeleton with her coffin and grave goods. Even more recent investigations found that, though the burial appeared to be purposely set apart from other graves, it was unlikely the deceased was a princess or aristocrat—her burial was too similar to others from the Roman Iron Age in Poland. It only appeared that she been buried alone because her coffin had been exposed by coastal erosion.

Unknowns still lingered, however. Despite the grave goods being dated to the first half of the 2nd century C.E., analysis of the woman’s tooth showed that it was over a hundred years older. Archaeologist Marta Chmiel-Chrzanowska (who had previously studied the remains) was determined to find an answer to this puzzle of mis-matched dates, and she thought it might lie in the wood of the coffin. Dendrochronological dating would have been too invasive to carry out with older methods, which is why research on wooden Roman Iron Age artifacts in the region had been limited, but updates made it possible to date wood from much smaller samples. Chmiel-Chrzanowska was finally authorized to sample material from the coffin, and put the mystery of its age to rest.

“To determine whether this discrepancy is due to a reservoir effect or a misclassification of the finds, it was deemed necessary to conduct dendrochronological studies,” she said in a study recently published in the journal Archaeometry. “However, due to the unique nature of this discovery—the only preserved wooden sarcophagus of its kind from the Roman Iron Age—the primary concern was the risk of damage.”

Wilebark coffins were often made of hollowed tree trunks—something also seen in other burials of the ancient Slavic world, such as that of the famous Scythian “ice maiden.” Unfortunately, many Wielbark burials deteriorated and left little more behind than dark stains in the soil, which explains why this fallen burial was so rare.

Even rarer is the level of its preservation. This was made possible by the existence of an anoxic environment that prevented organic materials from degrading, which is thought to be the result of water levels rising and submerging coastal land. By sampling a section that included sapwood (the younger layers of a tree’s vascular tissues) and measuring the width of the growth rings, in addition to measuring the total annual growth rings, Chmiel-Chrzanowska and her team were able to date the wood to some time between 112 and 128 C.E.

Why exactly the radiocarbon dating of the tooth present in the remains suggested that the young woman had died a century before her coffin was made, however, still eluded the archaeologists. One theory is based on the fact that the nitrogen, oxygen and strontium content of her teeth and enamel suggested a diet high in animal protein. If at least some of that protein came from fish, the marine carbon—which contains lower levels of the carbon-14 isotope—could have artificially altered her perceived age. Another theory is that the woman could have been eating food that was not local, and while the molar studied reflected a diet local to the Baltic Sea basin where she lived, foreign food could have also had an aging effect.

“This finding is crucial for improving future radiocarbon dating interpretations, especially in regions with high water hardness,” said Chmiel-Chrzanowska. “Strontium and stable isotope analyses suggest that the woman may not have been a local inhabitant, raising questions about mobility and cultural exchanges in the Roman Iron Age.”