Curious residents of Nederland, Colo., watched recently as two men pulled what looked like a small sled through the town cemetery. Nearby, a woman inched her way among the headstones like an edgy tightrope walker gripping a 15-foot-long metal rod.
For spectators wondering what was up, the answer probably surprised them. A University of Colorado at Boulder geophysics class armed with high-tech equipment was searching for unmarked graves and empty plots in the historic mountain community聮s cemetery as part of a project undertaken for Nederland town administrators.
Led by geological sciences Associate Professor Craig Jones, the class used ground penetrating radar, a resistivity machine and a magnetic sensor -- all capable of locating buried metal, including lead-lined coffins. Despite a few technical glitches, they located several unmarked graves and several empty plots previously believed to be occupied.
Founded in 1864 during the Colorado gold rush, Nederland (then called Brownville) had two graveyards in its early years, said Nederland Mayor Jim Miller. One, begun in 1875, was built on land that later gave way to the Antlers Hotel in the late 1930s. The headstones and coffins from that cemetery were transferred to the other town cemetery, located on a hillside in northwest Nederland off Highway 72.
Today, Nederland聮s cemetery is a hodge-podge of gravesites. Because of the rocky, sloping terrain and shallow bedrock, the graves were dug in places where rocks were least abundant. "As you can see, there are a lot of miners and a lot of babies buried here," said Nederland Historical Society Director Glenna Carline. "Life was very hard back then."
As with many graveyards, weathering and vandalism have taken their toll on the cemetery. Headstones have eroded or been displaced, making it difficult to pinpoint not only the gravesites, but the occupants. "Fortunately, we recently got some funding that will allow us to erect a new cemetery sign, put in new fencing around the cemetery and pipe water to the site to keep the vegetation green," Carline said.
"We knew we needed an accurate, historical inventory of the cemetery for our archives, and also to see if we had any plots available to sell," said Miller, who has had inquiries from long-time Nederland residents seeking permanent resting places. The local historical society is working on an accurate map of all gravesites and photos of each.
The 15-foot-long pole wielded by the student was actually a resistivity machine that generates and sends a magnetic current underground, then collects the results at the pole聮s opposite end. A spike in the data indicates a significant amount of metal underground as reflected by an increase in electrical conductivity, said Jones, also a fellow of the Cooperative Institute for Research in Environmental Sciences headquartered on campus.
Although the ground-penetrating radar sled picked up three graves during its first short pass over a small part of the cemetery, the signals were a bit sketchy, said Jones. "But we did pick up a strange signal about 20 feet below the ground in the cemetery, below the bedrock," said Jones. "It could be a vein of ore, it could be a mineshaft, we just don聮t know."
But the ground-penetrating radar problems were overshadowed by the success of the resistivity machine. "The signal of metal just came howling out of the ground when we passed the resistivity instrument over coffins," said Jones.
Senior Ryan Thomas said the team was hoping the resistivity machine or ground-penetrating radar might even pick up wooden coffins or even coffinless graves. "Since the underground current measures the conductivity of electricity through soil and other buried objects, the read-outs could conceivably show places where the soil was disturbed by the digging and back-filling of graves," he said.
"This is a great field of opportunity for the students," said Otina Fox, a CU-Boulder doctoral student and teaching assistant for the class. "It聮s a small enough class where everyone gets hands-on time with the geophysics instruments."
Miller called the project "a win-win" situation. "I聮m sure the students gained valuable experience, and we got our immediate problems solved for Nederland in terms of available plots. We also got additional information on old burials by locals who stopped by during the project, and we look forward to working with CU again."
Although the class of four undergraduates, two graduate students and a teaching assistant was able to survey only part the cemetery on a sunny September morning, the graduate students will return to the cemetery the weekend of Oct. 14-15 to survey the oldest part of the cemetery, Jones said. "We will have lot of data to analyze."