What’s under there? Checking Woodstock Cemetery grounds for space with radar

Dr. John Rayburn and students. (Photo by Violet Snow)

SUNY New Paltz geology professor John Rayburn and two of his students came to the Woodstock Cemetery on June 26 with ground-penetrating radar equipment to determine what lies under sections of the property that are without gravestones. Members of the cemetery task force hope to find out if there are areas that could someday be used for burials, either of coffins or cremation urns.

The cemetery, located on the east side of Rock City Road, was taken over last year by the town when the private cemetery association in charge could no longer maintain the property. The “empty” sections are probably unused because they’re underlaid by bedrock near the surface, but some areas might contain unmarked paupers’ graves. Both situations will show up in the radar data.

The New Paltz team recently examined a property in Kingston that was suspected of having been an African-American graveyard. They confirmed the presence of graves under the surface, and the land has since been purchased for preservation as the Pine Street African Burial Ground. Rayburn agreed to survey the Woodstock Cemetery at no cost, as a teaching experience for his students.

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On a sunny June morning, they began by laying out a 10-meter by 10-meter grid at the front of the cemetery, using white cable marked with red every half-meter. Nearby, rocky outcroppings indicated the probability of bedrock underneath. The radar will reveal the depth of the soil on top, which might be sufficient for burial of cremation urns.

“That’s going to be alluvial soil along the fence,” Rayburn told his students, “and over there should be till,” referring to the cemetery’s long, narrow north-south ridges, which are drumlins deposited by glaciers.

He assembled the two pieces of a wheeled device, the SmartCart 250, which resembles a lawn mower, then mounted a computer, the Noggin, on the handle. He pointed to the lower part of the cart. “The front sends a signal into the ground, and the back listens. If the radar waves bounce off anything, the machine picks it up. Today we’re looking for disturbances in the soil. The waves will bounce off rock, a metal casket, or a buried pipe, but a wooden coffin may have deteriorated. If you once dug a hole, it changed the arrangement of the soil, and the radar picks that up.”

The computer compiles the data into a three-dimensional map that can be overlaid on Google Earth’s digital maps, since the cart includes a GPS. For the front section of the cemetery, Rayburn programmed the computer to gather data up to a depth of two meters, since his initial sweep with the device showed bedrock about a meter and a half down. He also determined the soil velocity, the speed at which the waves will move through the soil, which is dependent on the amount of moisture in the soil and enables the measurement of depth. Then his students took turns guiding the 250 across the grid at half-meter intervals.

The data, which consists of 3-D slices, will be analyzed at the university, where the computers have filters and sophisticated processing capabilities. Then Rayburn will email the results to cemetery task force chair Teri Reynolds.

The team spent eight hours working on eight 10-by-10 grids at various locations: the front, the hill containing Civil War graves, the top of the knoll off to the side, and the very back of the cemetery. “He emailed and said there is a lot of data to go over,” Reynolds reported two days after the survey, “plus a couple of areas that need more investigation.” She hopes to receive results from Rayburn in a week or two. He will also run the data by another New Paltz professor, Dr. Joe Diamond, whose archeological expertise will help to interpret the findings.

We’ll report back when the results are in.

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