Archaeologists scan for ancient burial grounds at Afton park

Updated: 4:18 p.m. | Posted: 2:20 p.m.

Archaeologists are scanning the earth in southeast Minnesota to determine whether a proposed $4 million wastewater treatment project might threaten ancient American Indian burial sites.

The St. Paul Pioneer Press reports that archaeologists Geoff Jones and David Thiel of Archaeo-Physics, LLC, conducted electrical resistance testing at Steamboat Park in Afton on Monday. They used a device to test the soil's electrical resistance in an effort to measure modern disturbances and the presence of archaeological features.

Each reading, roughly six samples per square meter, will be used to produce a map of the site.

"The more samples you collect, the better the picture is going to be," said Jones, who specializes in geophysical surveying and high-resolution subsurface mapping. "Based on the nature of the site, we're collecting data at very high-sample densities. We take all these readings, and we put them together like pixels in an image, and that's our map of the site."

To prepare for the job, Jones studied the work of archaeologist T.H. Lewis, who conducted surveys and mapped Indian burial grounds in Minnesota in the 1880s, including a survey of the Rattlesnake Effigy in Afton.

Lewis "is a personal hero of mine," Jones said. "His surveys were usually very accurate. I tried to map out, from his survey notes, where these mounds originally were exactly. It was pretty well-known, but I got it nailed down pretty accurately."

The tests were requested by the Minnesota Indian Affairs Council, a state-level agency, because it's concerned that the sewer project's storm-water retention pond could pose a risk to the nearby burial mound called Rattlesnake Effigy.

The city of Afton will pay $4,700 for the tests, which will focus on the wastewater treatment project's stormwater pond, the stormwater lift station and the sanitary sewer lift station, according to City Administrator Ron Moorse.

"The information we have is that that area has been substantially disturbed, and we don't expect that we will find anything," Moorse said, adding that no human bones have been found in the park.

Jones agrees that the amount of disturbance at the site "has been considerable," but he declined to comment on whether there are intact archaeological features below ground.

"I may do more to simply document disturbance than find the original features," he said. "The biggest concern here is not just the cultural history aspect of what these mounds might mean, but there is always a possibility that there are burials here, and protecting those is really a high priority."

Later this week, Jones plans to conduct ground-penetrating radar to clarify the location of the mound.

Another company will conduct shovel testing in the park.