An Astonishing Discovery

Researchers Discover Secret Chambers in Hallstatt

There are still many mysteries in Hallstatt(Bild: Andreas Tischler)

While searching for remnants of prehistoric salt mining in Hallstatt, archaeologists from the Natural History Museum (NHM) discovered a vast complex of mining chambers dating back to the Iron Age during exploratory drilling. The complex consists of several parallel chambers stretching over 300 meters.

As early as about 7,300 years ago, people settled in the high valley above Hallstatt and mined salt. This is evidenced by Neolithic tools found inside the mountain, such as deer antler chisels and stone tools. Starting in 1200 B.C., mining operations reached nearly industrial scales, with daily production of about 1.5 metric tons of salt. Several phases of mining in the prehistoric salt mine were each brought to an end by massive landslides, during which the cavities were filled with material from the surface.

A Resilient Community
“But mining continued nonetheless. This was a very resilient community that was supplying salt again just a few years after these landslides,” Daniel Brandner, head of the underground excavations at the NHM’s Prehistory Department, told the APA.

“Man in the Salt”
This is also how we know about Iron Age salt mining, which began in the 6th century BCE. The famous “Man in the Salt” also dates from this period: in 1734, the exceptionally well-preserved body of a miner was found, who is believed to have perished in a massive landslide. At the time, his prehistoric age was not recognized, and the body was buried in the local cemetery.

Untouched Areas of the Prehistoric Mine“
 ” However, prehistoric mining is known only in those places where historical salt mining happened to overlap with it. In 2022, exploratory drilling began using a core drilling rig from Salinen Austria AG, which is typically used for geological surveys and can penetrate hundreds of meters into the mountain to explore previously untouched areas of the salt mine.

Never Seen Before
The initial assumption of a single, massive cavity was not confirmed. “These are several parallel chambers, arranged both above and below one another,” said Brandner. “We’ve never seen anything like this in Hallstatt,” the archaeologist emphasized. This form of mining demonstrates a clear adaptation by the prehistoric miners to the geology, as they followed the salt veins deep within the mountain.

A layer of waste up to nine meters high
So far, the researchers have been able to trace this mining activity over a length of 300 meters, with the chambers measuring 25 meters in width and about 20 meters in height. The floor is covered by a layer of mining waste from the prehistoric miners up to nine meters thick, consisting of burned pine chips, broken tools, pieces of clothing, and human excrement. In the formerly open cavity above, the chambers are filled with material from the surface, which likely originated from a landslide.

Similarities with Hallein
Initial excavations in these chambers allow archaeologists to “gain insight, down to the smallest detail, into the previously unexamined phase of Iron Age salt mining and the mining techniques of that time.” Compared to earlier mining phases, the finds reveal a great many changes, and they “strikingly and surprisingly” correspond to those from the Dürrnberg near Hallein (Salzburg), where salt mining also began in the 6th century BCE.

Tools and Food Remains
For example, the finds of tools reveal different types of handles on the mining tools. Typically, these tools were highly standardized and specifically adapted to the requirements of the mining techniques. However, this clearly changed over the course of the Iron Age, according to the archaeologist. Textiles and remnants of clothing, exceptionally well-preserved by the salt, were also found, as well as wooden bowls containing food remains and the miners’ excrement. Not only is the genetic material of the individuals involved well-preserved, but also DNA from the food they consumed, which has been preserved in the sediment.

New Analytical Methods
In addition to the work in the Iron Age mining chambers, archaeologists—in cooperation with the saltworks and the Salzwelten—are working on a large-scale restoration project funded by the federal government and the state of Upper Austria to make earlier excavation sites accessible to researchers once again. “This enables us to examine sites where we haven’t been able to collect data for decades using new analytical methods and addressing new research questions,” says Brandner. To this end, the tunnels—some of which are 200 to 300 years old—that lead to these sites are being restored, secured, and equipped with the necessary infrastructure to enable access and research for future generations.

“Archaeology on the Mountain”
At the “Archaeology onthe Mountain”event on September 12 and 13, the Hallstatt High Valley will once again be transformed into an open-air archaeological laboratory. This year’s event—in keeping with the new funicular to the Salzberg, which began operating at the end of August—will focus on the development of salt transport from prehistory to the present.