There was a time when plows were drawn across the prairie by early settlers, starting lives in a new world.
These early versions of the plow are long retired, and this week a very different piece of equipment is being drawn across the prairie at Homestead National Monument of America.
It’s called a magnetic gradiometer, and workers hope the device will uncover artifacts from the past buried underground at the National Park Service site.
“The thing about archaeology is that certain types of features create subtle variations in the Earth’s magnetic field, explained Adam Wiewel an archaeologist with the Lincoln-based Midwest Archeological Center. “Just imagine if we measure the orientation and the strength of the magnetic field at this location. If we moved over a little bit and happened to cross over a buried brick foundation, those bricks are magnetic, so they would create a change in the magnetic field. That’s what this instrument is measuring.”
The device features four wheels, the size of those found on a small bicycle, and a series of wires and equipment pointed directly at the ground. Everything on the gradiometer is nonmagnetic to avoid conflicting with the results, and it’s pulled roughly 10 feet behind a utility vehicle, just far enough away that the vehicle won’t skew signals.
An archaeological survey was last done at Homestead sometime in the 1980s, though the equipment wasn’t as advanced or efficient.
“We’re able to cover 15-20 acres a day with this,” Wiewel said. “In the past, we had smaller versions of these that are handheld and we would set up a grid and we might be able to cover one to two acres a day. This has really changed the way we’re able to survey large areas.”
An alternative approach would be shovel testing, though it’s time consuming, impossible to cover all areas and leaves holes in the prairie.
“We’re not impacting the site in a significant way,” Wiewel said. “We’re not putting in lots of shovel tests and large excavations. We can really limit those to small areas to confirm the results. This is a way of targeting features or identifying their locations, but also mapping them out across the prairie.”
Archaeologists mapped a portion of Homestead with the device, hoping to find relics of a Native American settlement, a kiln believed to be in the area and other items.
Wiewel will return in a couple weeks to dig and document, with a chance for the public to help.
“Once we do our survey, in a couple of weeks we’ll be back with a team and we’ll do a few test pits,” said Becky Wiewel with the Midwest Archeological Center. “We’re going to be working with public volunteers where people can see what we’re doing and come take part in it if they’re interested.”
Homestead park ranger Susan Cook said 900 students will visit as part of field trips to interact with archaeologists and learn about the prairie. Additionally, the public can sign up in advance to assist with the project on Saturday, May 4.
“It’s something that doesn’t happen very often, so this is an opportunity we can share with visitors to see another part of what the Park Service does,” Cook said. “We do protect the archaeology. We protect those type of things. A lot of people don’t thing about us having that kind of work also.”
Participants can sign up to volunteer starting on Saturday, April 20 when Homestead hosts a “Be a citizen scientist” event from 10 a.m. to 4 p.m. The event features several speakers for all ages who will present about entomology and other topics related to the prairie.