How to use radar technology to spot unmarked graves in a former boarding school

Warning: This story contains some details that may be painful for readers.

Before the first wave of electromagnetic waves entered the ground of the suspected boarding school cemetery, archaeologists may have collected key information from one of their most important sources: survivors.

Terence Clark, assistant professor of archaeology at the University of Saskatchewan, said that survivors have either heard the story or learned directly about the site itself over the years.

“We heard that many times children dig graves for other children, so they may know exactly where the grave is,” he said. “It’s unrealistic to go around the school hundreds of meters in all directions. It’s a bit like finding a needle in a haystack. But if we can talk to survivors who know specific information, then of course we can narrow the search.”

After Tk’emlúps te Secwépemc First Nation announced the shocking news last week, understanding the process and technology of detecting unmarked graves has become the focus of attention. It said that preliminary results of an investigation of the site of the former Kamloops Indian boarding school indicated that the remains of 215 children may have been buried at the site.

The decision was made by an expert using ground penetrating radar (GPR), a geophysical survey method to inspect the site. This technology is often used to determine the presence of underground pipelines, water pipes, or natural gas or sewer pipelines on site. But it can also be used to scan historic cemeteries and unmarked graves.

On Friday, Kukpi7 (chief) Rosanne Casimir (Rosanne Casimir) stated that they expect to release the final report on the findings of the former boarding school at the end of this month.

‘This is a very heavy process’

Dr. Kisha Supernant, an associate professor in the Department of Anthropology at the University of Alberta, told CBC Radio: “When you actually walk through these venues, I want to say that this is a very onerous process.” Day 6.

GPR equipment includes a transmitting antenna that sends high-frequency electromagnetic waves to the ground. If they hit any object that is different from the soil medium, the antenna will bounce back to the receiver. (Provided by Geoscan)

“Of course, no one wants to find a child’s unmarked grave. But at the same time, we absolutely want to find that because we want to bring that closed place back to the community.”

In terms of technology, the survey team will use ground penetrating radar equipment to roll on the surface of the earth. According to BC-based GeoScan Subsurface Surveys, GPR is much like medical ultrasound, but instead, high-frequency radio waves penetrate the ground to form images that may be below.

Will Meredith, a founding member of GeoScan and a GPR expert, said that the device is a box with wheels about 25 cm wide, pushed or pulled by a technician who is in a process that looks a bit like a “virtual grass mowing”. Scan the land.

The device includes a radar transmitting antenna that sends high-frequency waves to the ground, and if they hit any object that is different from the soil medium, the antenna will bounce back to the receiver.

Day 613:48Archaeologists say more support is needed to investigate other suspected cemeteries at the boarding school

After Tk’emlúps te Secwépemc First Nation said the remains of 215 children were found during an initial scan at the site of a former boarding school in Kamloops, British Columbia, Indigenous communities across Canada demanded their territory. Three indigenous women reflected on the importance of counting all the children who died in boarding schools, and Kisha Supernant, a Metis archaeologist at the University of Alberta, explained how she used ground penetrating radar to help indigenous communities carry out this work. 13:48

Supernant said her team will arrange a square, about 50 meters by 50 meters, and then drag the GPR box across the ground. She said they would try to keep the lines as close as possible-her agreement was 25 centimeters apart.

“This ensures that we cover all the ground below the radar box itself. This is a slow process,” she said.

The equipment itself must be able to touch the ground, which means that any brushes or tall grass must be removed before any work is done to get good results, Clark said.

“I just worked on a project about unmarked graves earlier this week. Our team spent a lot of time cleaning up thorns, bushes and all these things so that we can really see the ground.”

Clark said that the computer can recombine all these lines and view the results in three dimensions.

This computer diagram shows the types of images that can be generated from a ground penetrating radar with a known location of a grave. (Provided by GeoScan)

“It’s really tricky. If you go through a small grave and get only a little bit at a time, you will get the rest next time. Then you can figure out what’s going on there,” he said.

Technology can’t recognize organic matter

However, the technology cannot pick up organic matter, which means it cannot determine whether the bone remains are below.

Steve Watson, owner of the global GPR Services company based in Ontario, said that over time, the bones will absorb minerals from the soil and become very similar to the soil.

He said that if this is a relatively new tomb, within a few years, technicians may be able to identify bones or identify an object that looks like bones.

“If you have something that is 50, 60 or 100 or 200 years old, you won’t see the bones,” he said. .

Instead, technicians will look for “turning the soil,” Watson said.

The soil is made up of micro-layers, and when you put the shovel in the ground, “you mix the soil with electricity and it becomes different from the natural soil next to it,” he said.

“So this is what we can see through GPR, this area has become soil.”

Archaeologists Kisha Supernant (right) and Terence Clark use ground penetrating radar to find unmarked graves. (Kisha Supernant)

Clark said the way they found the tombs was that they saw “very consistent formations, everything is the same.

“Then we basically saw an area that was excavated,” he said. “So we got this anomaly. It seems to be much softer than the soil around it.”

Clark said that, despite this, investigating unmarked, unplanned graves without a specific direction can be a challenge.

“There are a lot of things near the surface, such as tree roots and gopher holes, and all kinds of things that might confuse what happened in the first 30 or 40 centimeters,” he said.

“It may be buried in one place, and then 30, 40, 50 years later, because it is not marked, there may be another burial intersecting with it. So they become more complicated and have to figure out what happened.”

Supernant said they were very careful in communicating what they found to the wider indigenous community and made sure to explain that if they found anything, it was a tomb, not a human remains.

So it’s not the body. This is not an X-ray, we can see the axis. If there is a coffin, we can sometimes detect the coffin in the signal,” she said.

We can usually tell immediately whether we have found something. Some additional processing is required to confirm that what we are seeing may be a grave. But we have done enough now, and you will see changes in the signal, which can usually point to what is happening.

“This is both heartbreaking and the reason why we are there.”

Anyone affected by the boarding school experience and those affected by the latest report can receive support.

A nationwide Indian boarding school crisis hotline has been established to provide support to former students and those affected. People can call the 24-hour national crisis hotline: 1-866-925-4419 for emotional and crisis referral services.

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