The grave of an elite youngster from the seventh century has started to thaw after being transferred from its discovery location in a single flash-frozen block, a scientific first
In Tussenhausen, Bavaria, a stone chamber grave was found in October at the site of a new construction. The results of the archaeological investigation unearthed the remnants of a Roman-era structure.
Later, when the young child had passed away, the structure was utilized to house his final resting place. He had been interred in a chamber burial with a brick floor and solid stone slab walls and ceiling. His skeleton remains were discovered with pricey jewelry on.
At his feet was a dog’s skeleton. Baby teeth indicate the boy was no older than 10 years old when he died, but despite his young age, he was well-armed.
He was identified as a member of the affluent warrior elite by a sword and a weapon belt embellished with gold studs. Additionally discovered in the grave were silver bracelets, spurs, crosses made of sheet gold, and a bronze basin.
Because the tomb’s stone walls and ceiling were so closely connected, sediments have not entered the interior for 1,300 years. As a result, the burial was in fantastic shape and the fill still contained traces of organic items like leather and textiles.
The fact that the bones were not buried in relatively solid soil that could be carved out in a block for the kind of laboratory excavation that can preserve even the tiniest remnants of archaeological material presented a problem to conservators despite this lucky break. The priceless, delicate remains were at danger of being jostled and harmed during shipment without load-bearing fillings.
To preserve the materials with as little deterioration as possible, archaeologists from the Bavarian State Office for the Preservation of Monuments (BLfD) devised a new technique. The stone walls were removed, replaced with wooden panels for temporary protection.
A plate was pushed under the grave over the brick floor. The grave was wetted down layer by layer, and each layer flash-frozen with liquid nitrogen at -320F. The low temperature of liquid nitrogen ensures the water hardens instantly into ice without expanding or forming ice crystals as it would if it were frozen at a higher temperature.
The soil around it was then cut away with heavy machinery and the whole frozen block lifted out by crane. The whole process took 14 hours, from 3 AM to 5 PM.
The frozen grave was transported to the BLfD conservation laboratory in Bamberg. Where it was kept frozen until it could be thawed and excavated in controlled conditions. The thawing has now begun.
“The block salvage with the child’s skeleton was stored in a freezer for several months. Now the nickname of our little “ice prince” will soon be obsolete. His protective ice armor is being carefully and successively broken down through targeted heating.
Our restorer team has prepared this process meticulously,” explains General Curator Prof. Dipl.-Ing. Mathias Pfeil, Head of the Bavarian State Office for the Preservation of Monuments.
For the thawing process, the salvage block, which has been deep-frozen for several months and weighs around 800 kilograms, is brought from the freezer cell into a specially prepared room whose humidity can be controlled and adjusted according to the state of preservation of the block.
To ensure that the condensation water that is released does not damage the finds, it is drained off using a special suction device.
During breaks in processing, a cooling hood ensures a constant temperature of minus 4 degrees Celsius. Thawing is expected to take several days. Afterward, experts such as anthropologists and archaeobotanists will analyze the first material samples.
The more detailed investigation and documentation work planned in recent months is to begin later. These will probably also provide information about the circumstances of the burial, the cause of death and the age of the child.
“Numerous remains of fabric and leather, for example from the scabbard, the weapon belt, and the clothing, have been preserved.
They promise extremely interesting insights into the grave furnishings and into early medieval textile technology,” says Britt Nowak-Böck, head of the archaeological restoration workshops of the Bavarian State Office for Monument Preservation.
Source: us.pahilopahilonews.com
