Evrim Yazgin
Cosmos science journalist
Archaeologists using new methods have unlocked more mysteries of ancient human development hidden under the surface in southern Africa. And it involves no digging.
Southern Africa is a treasure trove of ancient human artefacts and fossils. South Africa’s 120,000-acre Cradle of Humankind UNESCO World Heritage Site has the highest concentration of prehistoric human remains in the world.
But finds have mostly come from caves and rock shelters where ancient bones and tools are well preserved.
The new study published in the journal Geoarchaeology shows that geophysical imaging methods can be useful to find other artefacts in open air sites outside caves and rock shelters.
“Caves and rock shelters offer a good preservation of the record at the time, but they only represent a narrow slice of the past landscape,” says lead author Oliver Hatswell, a PhD Candidate at South Australia’s Flinders University.
“By relying so heavily on them, we risk missing the broader picture of how early humans lived, moved, and interacted with their environment,” Hatswell adds.
“While they might be more difficult and costly to survey and excavate, open-air sites represent the majority of archaeological sites worldwide, so it’s important we find suitable ways to investigate and include that information in our interpretations of the past.”
Geophysical methods including electrical resistivity tomography (ERT) and magnetometry show promise as tools to map the features beneath the surface.
The non-invasive geophysical imagery tools were used at the Klein Hoek 1 (KH1) site in South Africa’s Doring River catchment, about 200km north of Cape Town.
KH1 is a rare and significant open-air location where 6,747 ancient human artefacts have been discovered. This includes a cluster of over 180 stone tools dating back approximately 70,000 to 75,000 years.
“This cluster of stone tools have been found eroding out of ancient layers of soil, giving us a rare chance to study how early humans lived and used the land across a wide area,” Hatswell says. “However, the site also exemplifies the paradox of open-air archaeology; we can see these artefacts because the areas have been damaged by erosion, while the parts that are better preserved don’t always show anything on the surface.”
Geophysical imaging revealed specific rock characteristics and potential ancient human evidence without needing extensive digging.
ERT revealed layers of sediment, including those likely to hold stone tools. In some places, these layers reached 8m beneath the surface. Magnetometry surveys detected subtle magnetic anomalies that could indicate where ancient humans lit fires or have other archaeological features.
Geophysics is used for archaeological research of much younger artefacts and remains. The fact that these tools have shown promise for prehistoric sites means they could greatly expand the amount of archaeological material at KH1 and other Stone Age and older sites around the world, the team says.
“The combination of ERT and magnetometry provides a powerful toolkit for archaeologists working in open-air contexts,” says senior co-author Ian Moffat, also at Flinders. “These methods not only reduce the time and cost associated with traditional excavation but also help us target areas with the highest potential for meaningful discoveries.”
