1300-year-old child’s grave recovered using shock freezing technology

A team of restorers, archaeologists and excavation technicians from the Bavarian State Office for the Preservation of Historical Monuments have recovered a child’s grave in the Allgäu region that is around 1300 years old using a new method: it was frozen together with the surrounding soil – and lifted out of the ground

Every excavation usually leads inevitably to the destruction of an excavation find, which is why exact documentation of the find site is absolutely essential. However, there is another way of recording the circumstances of the find itself: During the recent excavation of an early medieval child’s grave in Tussenhausen (Unterallgäu), the grave was covered with an ice shell in order to lift it out of the ground as a whole. The grave contents were wetted with water and shock-frozen with liquid nitrogen to minus 196 degrees Celsius. Monument conservators developed the method to protect the unusually well-preserved burial of the armed boy and dog from damage. A team of restorers, archaeologists and excavation technicians from the Bavarian State Office for the Preservation of Monuments developed the new method. This enabled them to lift the exceptionally well-preserved child’s grave from the 7th century out of the ground as a whole and transport it carefully to the laboratory.

The burial, which was exposed as a block and protected by wooden slabs on the sides, was frozen layer by layer with liquid nitrogen. The sword placed in the boy’s grave, but above all the accompanying weapon belt decorated with gold fittings and the rich jewelry suggest that the child belonged to a wealthy and elite social class. But there is something else special about this grave: the finds remained in it almost unchanged for almost 1300 years because the stone ceiling and walls of the burial chamber were obviously so tightly sealed that, unlike usual, no sediment penetrated into the coffin. As a result, the finds are in excellent condition for a grave from this period. Even numerous pieces of fabric and leather have been preserved – from the sword scabbard, the weapon belt, but also from the clothing and perhaps the shroud. “This burial is a stroke of luck for us, especially because so many pieces of fabric have been preserved. They promise highly interesting insights into the world of early medieval fashion. Our intensive research in recent years gives us an idea of the importance of high-quality textiles and decorated leather for the representation of status in the early Middle Ages. We expect the finds that have now been recovered to provide us with new insights into the textiles used at the time and how they were worn,” says General Conservator Prof. Dipl.-Ing. Mathias Pfeil, Head of the Bavarian State Office for the Preservation of Monuments. However, the fact that the burial was sediment-free posed a major challenge for the monument conservators. Without the stabilizing deposits from the soil, the finds were at risk of slipping or being damaged during recovery and transport on the brick floor of the burial chamber. For this reason, they were frozen and then pulled out of the ground by a crane, as if on a tray, with the help of a plate that was pushed under the bottom of the coffin.

The recovery took 14 hours

Liquid nitrogen was chosen because its temperature of -196 °C ensures that the applied water film hardens immediately without any expansion effects. In this way, no structurally destructive large ice crystals are formed. The recovery took a total of 14 hours – from 3 am to 5 pm. The burial is now in the block in the laboratory of the restoration workshops of the Bavarian State Office for the Preservation of Monuments in Bamberg, where it is initially housed in a cold chamber and will then be examined more closely and conserved. For this purpose, the ice will be melted in a controlled manner. An exact date for this has not yet been set. The traces of a square building, around eight meters wide, that archaeologists found in the ground are also striking. The building dates back to Roman times and was prepared a few centuries later as a prominent burial place for the child. It is not unusual for burials of this period to have objects with Christian symbolism alongside grave goods. For example, gold leaf crosses were found in the child’s grave.

Gold leaf crosses, silver, spurs and a bronze basin as grave goods

Silver bracelets, spurs and a bronze basin were also placed in the child’s burial chamber. Its exact age can only be determined after further investigations. As it still had milk teeth, the researchers assume that it was probably no more than ten years old at the time of death. The dog was placed at the child’s feet. No evidence of violence has been found on the animal’s remains so far. Nothing can be said about the cause of the child’s death either. The excavations took place as part of the development of a new building area in the Mattsies district. As archaeological monuments were already suspected at this location, the Bavarian State Office for the Preservation of Monuments was consulted at an early stage. The municipality actively supported the excavation of the 1300-year-old child’s grave with vehicles and personnel from the municipal building yard.

Watch the video here to see how the early medieval child’s grave was recovered for the first time using shock freezing technology.

Another sensational find: in 2014, archaeologists in Oberding (Erding district) came across a deposit of almost 800 Early Bronze Age barrows. After extensive restoration work and scientific analysis, scientists presented the sensational find in 2017. Read more here.

Reading tip: Read more about the successful collaboration between conservators and archaeologists at the Römisch-Germanisches Zentralmuseum (RGZM) in issue 7/2019.