New radiocarbon dates have somewhat “rejuvenated” the date of the sinking of the Kyrenia ship and made it possible to refine the radiocarbon calibration curve.
The Kyrenia ship sank off the coast of Cyprus, most likely between 286 and 272 BC. These dates were given by radiocarbon dating of almonds that were part of the ship’s cargo, as well as fragments of wood, including those that had undergone special cleaning. In the process, it was also possible to correct the radiocarbon calibration curve (see below) for the period 433–250 BC. The results of the work were published in the journal «PLOS ONE».
The ship was discovered at a depth of about 30 meters in 1965. In 1968-1969, it was studied by an expedition led by Michael Katz from the University of Pennsylvania. The hull of the ship was well preserved and in 1970, its parts were raised to the surface. After five years of conservation, the ship was exhibited in Kyrenia Castle. The ship was about 15 meters long, judging by the finds, it was operated by a crew of four people. About 400 amphorae were found inside it, they carried not only wine and olive oil, but also almonds. In addition, the ship had stone millstones and iron blanks. Most of the amphorae were from Rhodes, but some vessels came from other places. The good preservation of the ship’s hull made it possible not only to study its structure, but also to create replicas (at least three).
In addition to the amphorae, a small number of coins were also found on the ship. Based on them, the wreck was initially dated to the end of the 4th century BC. Recently, this date was shifted to 294–290 BC. The authors of the article decided to check it radiocarbon dating.
The problem was that polyethyleneglycol was used to preserve the Kyrenia ship to protect the wood from deterioration. This polymer is a petroleum product, meaning it contains its own ancient carbon, which contaminates the samples and prevents them from being dated using the radiocarbon method. There are several ways to overcome this obstacle, such as finding uncontaminated samples, trying to clean contaminated ones, or using other dating methods. The authors of the article decided to try all of these options.
To date the tree they used dendrochronology. It showed that the trees used to build the ship grew in the middle and second half of the 4th century BC. Since there was no wood on the ship’s planks, it is impossible to determine when they were cut down. According to rough estimates, this could have happened between 355 and 291 BC.
For the “contaminated” wood, the researchers developed a special method for removing polyethylene glycol. To test its effectiveness, they cleaned a Roman-era sample from Colchester, Britain, for which dendrochronological dates were known. The radiocarbon date obtained for the sample after cleaning matched the dendrochronological date. The new method was then applied to a sample from a shipwreck.
To make the dates more precise, the authors of the study also used a piece of wood that was raised from the bottom in the 1960s. It was so small that it was not used in the reconstruction of the ship and was not soaked in polyethylene glycol. It had been lying in a jar of water in a museum for more than 50 years. Other organic materials were also sent for analysis: almonds, of which there were many on the ship, and astragals – gambling chips made from animal bones.
Statistical processing of all the new radiocarbon dates showed that the ship sank between 305 and 271 BC, and the most likely date of the wreck is 286–272 BC. This is several years earlier than the archaeological finds, which, theoretically, will allow us to refine their dates, or (more likely) once again show the difference between when the objects were created and when they “fell” into the cultural layer.
At the same time, the new dates did not correlate well with calibration curve – a scale that correlates radiocarbon measurements with dendrochronological ones. Since the accumulation of radiocarbon in nature is uneven, such a scale is needed to correct the dating results. Turning to the discrepancies, the researchers found that the curve of the period between 350 and 250 BC is based on only a few radiocarbon measurements made in the 1990s and 1990s using an outdated method. Therefore, the authors of the article had to correct this section of the curve. They took cuts of sequoia and oak trees that lived between 433 and 250 BC and measured the radiocarbon content in the annual rings. After such a recalibration of the curve, the contradiction between it and the new date of the Kyrenia ship was eliminated.
Based on materials The Cornell Chronicle.
Source: www.nkj.ru
