Surprising Discovery Reveals Secrets of Ancient Greek Ship

Hull of the ship Kyrenia during excavation. The hull of the Kyrenia on the seabed off northern Cyprus during underwater excavations in the late 1960s. Credit: Image provided to the authors by the Kyrenia excavation team for use with this paper, CC-BY 4.0

Cornell researchers have refined the estimated period of sinking of the Kyrenia shipwreck between 286-272 BC by overcoming dating challenges such as removing contaminants and revising the radiocarbon calibration curve, improving both historical understanding and further research. widely scientific.

Historic shipwrecks often evoke dreams of sunken treasures waiting at the bottom of the ocean to be recovered.

For Cornell researchers trying to date the famous Hellenistic-era ship Kyrenia, which was discovered and found off the coast of northern Cyprus in the 1960s, the real treasure was not gold coins, but thousands of almonds found in jars between loads.

The almonds, combined with newly cleaned wood samples and the team’s modeling and radiocarbon expertise, led the Cornell Tree-Ring Laboratory to identify the most likely timeline for Kyrenia’s sinking between 296-271 BC, with a probability of great that happened between 286 -272 BC.

The team’s paper was published June 26 in the journal PLOS ONE. Lead author is Sturt Manning, Distinguished Professor of Arts and Sciences in Classical Archeology in the College of Arts and Sciences.

Kyrenia has a heritage known as the first large Greek ship of the Hellenistic period to be found, in 1965, with a mostly intact hull. From 1967-69, it was excavated along with its cargo, which included hundreds of pottery vessels, then reassembled off-site and scientifically studied.

“Kyrenia was one of the first times it was realized that this kind of rich evidence from the classical world could be found largely intact more than 2,000 years later on the seabed, if you could find it,” said Sturt Manning. “It was a bit of a milestone, the idea that you could actually dive and dig up and bring up a classical-era ship and discover this world of the past firsthand. Shipwrecks are unique time capsules and you can get an amazing save.”

The ship Kyrenia Hull remains

The hull of the Kyrenia remains shortly after refitting timbers recovered from seabed excavation. Credit: Image provided to the authors by the Kyrenia Ship Excavation Team for use with this paper, CC-BY 4.0

For the past six decades, Kyrenia has provided archaeologists and historians with key insights into the development of ancient ship technology, construction practices and maritime trade. To date, no less than three replicas of the Kyrenia have been produced and released, and these reconstructions have provided considerable information on the ancient ships and their sailing performance. However, the timeline of Cyrene’s origin and the exact date of its sinking has always been unclear at best. Initial attempts to date the ship were based on its artifacts found, such as pottery on board and a small hoard of coins, which initially led researchers to estimate that the ship was built and sunk in the late 300s BC.

“Classical texts and finds at port sites already told us that this era was important for extensive maritime trade and connections across the Mediterranean – an early period of globalization,” Manning said. “But the discovery of the ship Kyrenia, just under 15 meters long, probably with a crew of four, made this dramatically very immediate and real. It provided key insights into the practices of the earlier part of a millennium of intensive maritime activity in the Mediterranean, from Greece to Late Antiquity.”

The first volume of the definitive edition of the Kyrenia Ship Project, released last year, argued that the date of the wreck was slightly later, closer to 294-290 BC, but the main piece of evidence – a poorly preserved, almost illegible coin – it was not. waterproof.

Manning’s team, which included co-authors Madeleine Wenger ’24 and Brita Lorentzen, ’06, Ph.D. ’15, asked to secure a date.

The dangers of polyethylene glycol

The biggest obstacle to precisely dating Kyrenia has been another artifact, one from the 20th century: polyethylene glycol (PEG). Excavators and preservers often applied the petroleum-based compound to the water-saturated wood to prevent it from decaying after it was removed from the oxygen-free ocean environment.

“PEG was a standard treatment for decades. The problem is that it’s a petroleum product,” Manning said, “which means if you have PEG in the wood, you have this contamination from ancient fossil carbon that makes radiocarbon dating impossible.”

Manning’s team worked with researchers at the University of Groningen in the Netherlands to develop a new method for purifying PEG from wood, and they demonstrated it on PEG-treated Roman-era samples from Colchester, England, that had already established dendrochronological ( tree- sequence of rings) dates.

“We removed the PEG from the wood, radiocarbon dated it, and showed that in each case, we got a radiocarbon age consistent with the actual (known) age,” Manning said. “We’ve basically removed 99.9% of the PEG.”

They used that technique to remove PEG from a Kyrenia sample that Manning and colleagues had tried and failed to accurately date 10 years ago. The team also now dated a small, twisted piece of wood that was salvaged from Kyrenia in the late 1960s, but was too small to be included in the reconstruction, thus avoiding PEG treatment. It then sat in a jar of water in a museum for 50 odd years.

Dates indicated that the latest tree rings preserved from these timbers grew in the mid-to-late 4th century BC. Because the samples did not include bark, the researchers could not determine the exact date the original trees were cut down, but they could say that the date was likely after about 355-291 BC.

Organic evidence

Working with the original Kyrenia excavation team, the researchers examined its various artifacts, including pottery and coins, with a focus on organic materials, including an astragalus (a leg bone of a sheep or goat once used for games and rituals of divination in some ancient cultures) and thousands of fresh green almonds found in some of the large amphorae, ie ceramic jars. These “short-lived” sample materials helped determine the date of the ship’s last voyage.

The team applied statistical modeling combined with dendrochronology of the wood samples to obtain a level of dating that was much more accurate than previous attempts. Modeling identified the most likely date range for the final journey to be between 305-271 BC (95.4% probability) and 286-272 BC (68.3% probability) – several years more recent than current estimates.

But there was one big hiccup along the way. The new dates did not match the international radiocarbon calibration curve, which is based on tree rings of known age and is used to convert radiocarbon measurements to calendar dates for the Northern Hemisphere.

Manning took a closer look at the data behind the calibration curve, which has been collected over many decades by dozens of laboratories and hundreds of scientists. He found that the period between 350 and 250 BC had no modern accelerator mass spectrometry (AMS) radiocarbon data. Instead, the calibration curve in this period relied only on a few measurements made in the 1980s and 1990s using an older type of radiocarbon dating technology. With collaborators in the US and the Netherlands, the team measured samples of year-old sequoia and oak of known age to recalibrate the curve for the period 433-250 BC. This not only helped to explain a large increase in radiocarbon production caused by a minimum of solar activity centered around 360 BC, but also led to significant revisions of the curve in the period around 300 BC – improvements that were critical for the dating of Kyrenia.

Manning predicts that the new findings will not only clarify the timeline of Kyrenia and its payload, but also help researchers use the calibration curve for many different projects.

“This revised 400-250 BC curve now has connections to other problems that researchers are working on in Europe or China or elsewhere in the northern hemisphere,” he said. “Half of the people who cite the paper in the future will cite the fact that we revised the radiocarbon calibration curve in this period, and only half will say that the Kyrenia shipwreck is really important and has a much better date .”

Reference: “A Revised 350–250 BC Radiocarbon Calibration Curve Implicates High-Precision Dating of the Kyrenia Vessel” by Sturt W. Manning, Brita Lorentzen, Martin Bridge, Michael W. Dee, John Southon, and Madeleine Wenger, 26 June 2024, PLOS ONE.
DOI: 10.1371/ditar.pone.0302645

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