Echoes of the Past
By Olivia Kiley
Science and Tech Editor
Although ground penetrating radar (GPR) machines have been around since the 1930s, they are more relevant than ever for historians and archaeologists. These machines are used to capture images of materials in the ground without ever disturbing the surfaces. This technology is beneficial in areas where digging is either difficult or where it could potentially cause damage to an important site. But, before getting into the modern-day use of these radars, how do they work?
GPR was invented in 1929 by Walter Stern to survey the composition of a glacier. For many years following its invention, this technology was forgotten until American Air Force pilots crash-landed in Greenland after false altitude readings. This event sparked a renewed interest in mapping ice and subsoil properties.
Ground-penetrating radars work by sending electromagnetic pulses from an antenna into the ground. The pulses pass through the soil and subsurface objects and get distorted after a change in material. The pulse then travels back to the machine, where the data is recorded, and the changes in soil contents are displayed. This technology is especially useful for mapping groundwater levels, detecting underground explosives, and uncovering possible archaeological dig sites.
Although the most famous example of the use of GPR for Canadians was the discovery of mass burial sites of Indigenous children at residential schools.
Back in 2021, archaeologists discovered what could be upwards of 200 unmarked graves on the site of an old residential school in British Columbia. A couple of weeks later, 751 unmarked graves were found in Saskatchewan. GPR has been able to help indigenous peoples understand what happened to family members who never came home and piece together a history that was hidden for almost two hundred years.
Famous for its appearance in “Indiana Jones” as the resting place of the Holy Grail and its expertly carved façade into the side of a canyon wall, the Treasury monument in Petra, Jordan, is under the eye of many researchers and archaeologists once more after a team used GPR technology to uncover a hidden tomb, containing 12 complete sets of human remains and a variety of grave offerings. The radar pulses uncovered a void underneath the ground, and scientists were able to calculate and pinpoint the tomb’s exact location. However, they could not dig straight down as the tomb was directly under giant slabs of rock and such action could have jeopardized the integrity of the building. Instead, research teams dug by hand from the outside of the monument until they reached the tomb’s location.
“For as famous as it is, the Treasury is still a mystery to us in many ways.”
- Pearce Paul Creasman, director of the American Center of Research.
This discovery is significant to discerning the history of the Treasury as archaeologists do not know much about the monument. Its purpose is unknown, but by exploring tombs beneath it, maybe the Treasury’s use will one day come to light.
Ground-penetrating radars have been instrumental in the discovery of archaeological secrets. Using electromagnetic pulses, the machine creates an image of what is beneath the soil without affecting the surface at all. This technology is incredibly important to researchers and developers alike, showing that it is still relevant today despite being invented in the 1930s.