ground penetrating radar
Ground Radar for Unmarked Graves
Cemetery projects by Louise and Gerald Steding include searches for unmarked graves using their Mala Easy Locator radar,
ideal for archaeological sites.
GPR allows the buried story to be read without disturbing the site.
The level of detail typically includes, identification marked and unmarked graves, and possible unmarked graves, as well as fallen subsurface grave furniture, cemetery features, original boundaries, and occasionally outlying individuals.
For every cemetery recorded, we adapt and test our use of ground penetrating radar, lidar, and drone, in various environmental conditions.
Ground Penetrating Radar at its Baseline
In a fairly typical 2-D recording of unmarked graves in a cemetery, base lines are laid out for the GPR. As anomalies are encountered during this grid-survey, flags are used to mark possible burial locations. Using a total station, all findings are then plotted onto a plan. 3-D recordings are described under Data Visualisations.
Use of the radar is most effective on flat surfaces with a consistent soil matrix, in dry conditions. For our search purposes, we tested the usefulness of GPR in rough terrain at Sydney's Quarantine Station Cemetery No.3.
Here, both marked and unmarked graves were counted and compared to interment records.
Despite the rugged topography and dense vegetation, the accuracy of data recording and interpretation was estimated to be 78%.
Some individuals were then identified using surviving headstones, cemetery records, and interpolation.
The mapping of areas of high and low subsurface potential, and the positions of buried individuals are identified from our interpretation of radar hyperbolae shown in radargrams.
Human Burials in a Row
Images of individuals and objects appear as hyperbole on the radar screen. They are referred to as anomalies until the data has been interpreted and burials are identified physically and by experience. The image to the left shows a burial at a depth of 1.8 metres.
Searching the bush for pioneer burials.
While great for locating graves, ground penetrating radar can also be successfully used to locate other underground features, such as timber posts from a former internal fence and an extension to the ruins of the morgue at Goulburn's Jewish Cemetery.
RETURN TO COUNTRY
Shown above are the plastic flowers and cross placed on the coffin of Baby Michael Nichols at his burial in 1972. These decorations were located by Dr Steding during an exhumation.
Joining Michael's family in their search for his grave has been a highlight of our work. Baby Michael Nicholls was returned to his family and country in Armidale.
Please note: Return to families or return to country are the only reasons that we would exhume an Aboriginal person and would be at the request of Aboriginal people.
More recently an Aboriginal community showed us the site where they knew their relatives were buried in a mass grave. GPR results support this.
Ground penetrating radar particularly important for Aboriginal people and others who for cultural or religious reasons do not want their relatives to be disturbed. It is a non-intrusive method of identifying likely burials. Likewise, methods causing minimal disturbance exist for verification.
For cemetery and other burial projects, likely unmarked graves are pegged on site, giving visitors an immediate visual representation. They are then recorded using a total station and are shown on a user friendly site plan. Back in the office, the pegged anomalies are cross-checked with radargrams, their depths, and their GIS positions.
We welcome community input and hold demonstration days to show our findings.
During community projects, locals are encouraged to give the ground penetrating radar a go, to experience the search event and to see results for themselves in real time.
In a fieldtrip to Sydney's Quarantine Station Cemetery No.3, criminology students from Swinburne University were also shown how to use a ground penetrating radar.