Missing 150-year-old time capsule potentially found with CONQUEST®100 GPR Survey | Scanning
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Missing 150-year-old time capsule potentially found with CONQUEST®100

Dr.

Jarrod Burks from Ohio Valley Archaeology, Inc based in Columbus, Ohio, began offering geophysical services for archaeological applications in 2001 and subsequently implemented ground penetrating radar (GPR) surveys in the mid-2000s, with clients ranging from private contractors, historical societies, academics, and the U.S. Government.

With such a wide array of customers, Dr. Burks has had his fair share of unique applications for GPR and we are happy to share one of those.

Having done traditional archeological surveys in the past for the Jackson County Historical Society, Dr. Burks was approached by them to locate a time capsule that they knew was buried in one of the cornerstones of the Jackson County courthouse located in Jackson, Ohio. The cornerstone was laid in 1867, and since then locals had forgotten which corner the time capsule was in. As this project required a nondestructive and efficient means of imaging the insides of the cornerstores, Dr. Burks considered the use of GPR as a tool to attempt to locate this missing artifact.

A cornerstone is a ceremonial masonry stone set in a conspicuous side of a building and is often located above the actual foundation in a visible and prominent area, commonly the northeast corner of a structure. Cornerstones are also known to contain a cavity in which, historically, time capsules could be placed. Time capsules contain various artifacts relevant to the time period they are buried and are a historic repository of information that help preserve and collect items and messages as a thoughtful way of communicating with people in the future.

An issue Dr. Burks faced was that this project would require a high frequency GPR system which at the time he did not possess. He therefore approached his existing GPR manufacturer, Sensors & Software Inc to get a CONQUEST® 100 system that operates at a center frequency of 1000 MHz.
Despite having never used a CONQUEST® system before, Dr. Burks completed the whole project in about 1.5 hours. He said that the system was easy to use and as he got more practice with it, the survey went increasingly faster as he got more efficient in setting up the grid and scanning on the side of the building.

The investigation consisted of a grid scan of the three accessible building corners (SE, SW and NW) with the high resolution CONQUEST® 100 GPR system (Figure 1).

ground area scanning using gpr
Figure 1
Google Earth image of the Jackson County Courthouse survey site showing the 3 cornerstones, marked in yellow (SE, SW, NW) that were surveyed with the CONQUEST®100 System. The NW Corner where the time capsule might be is marked using a red star.

Each corner was scanned by combining two 24 x 24 inch grids into a 48 x 24 grid to cover 8 square feet (Figure 2).
 

Dr Burks using concrete gpr scanner
Figure 2
Dr. Burks, using the CONQUEST® 100 System to survey a 48 x 24-inch grid on the SW corner of the Jackson County Courthouse.

For two cornerstones (NW and SW) he surveyed both visible sides, but was able to only cover one side of remaining cornerstone (SE). Unfortunately, no potential target was detected at the first two corners on the south side of the building, which were the easiest to access. At the harder-to-access northwest corner, he detected a GPR anomaly that he attributed to either being an object or cavity within the sandstone cornerstone (Figures 3 and 4). After processing the grid scans into depth slices, in real time, right on the CONQUEST®100, the dimensions of the anomaly closely matched the dimensions of the time capsule from 1867 (Figures 3 and 4).

gprconcrete wall scanning
Figure 3
5 – 6 inch depth slice overlaid on a schematic of the NW Corner facing Broadway Street of the Jackson County Courthouse, showing the possible location of the time capsule with estimated object dimensions and depth. (Bottom) Photo of the northwest cornerstone showing the potential location (red star) of the time capsule.

 

concrete scanning with gpr
Figure 4
4 – 5 inch depth slice overlaid on a schematic of the NW corner facing E Main Street of the Jackson County Courthouse, showing the possible location of the time capsule
with estimated object dimensions and depth. (Bottom) Photo of the Conquest grid used for the survey with the potential location (red star) of the time capsule.

 

Post-processing was done to produce a 3D volume render of the object (Figure 5).

3D concrete scanning
Figure 5
3D volume visualization of the potential object likely to be the time capsule generated using the grid data collected over the northwest cornerstone of the Jackson County Courthouse.

So far, this 150 year old artifact has yet to be brought to light; the County has chosen not to try and extract the time capsule from the cornerstone as it is still a standing structure in use and they do not want to damage the original foundation of this historic building. A physical mark was left on the side of the building where the object is likely located.

Overall Dr. Burks had a very pleasant experience with the CONQUEST® GPR system and shared the following with us: “We detected something that could certainly be the time capsule. I am looking forward to the day when they can test the cornerstone to determine if in fact a time capsule is present.”

Stay tuned as we will share an update to this story once we hear the good news.

Story Courtesy of Dr. Jarrod Burks

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