Luther Alumni Magazine

Digging into ancient sites without moving a pebble

Linh Luong ’19 (left), a neuroscience major, chose to work with anthropology professor Colin Betts ’93 because, she says, “This is really good exposure to the research world. This allows me to look at data from a holistic perspective instead of as just one piece of information. I think that will apply to many other fields in my future.”
Linh Luong ’19 (left), a neuroscience major, chose to work with anthropology professor Colin Betts ’93 because, she says, “This is really good exposure to the research world. This allows me to look at data from a holistic perspective instead of as just one piece of information. I think that will apply to many other fields in my future.”

Anthropology professor Colin Betts ’93 began a long-term project this summer that has already collected unexpected and intriguing data from northeast Iowa’s mysterious effigy mounds. Using new remote-sensing equipment, he and student researchers were able to “see” into two effigy mounds—shaped like birds—without disturbing the ground. First looks at the data suggest the mound structures built by native peoples and dating to between 750 and 1000 A.D. were originally much more elaborate than they appear now.

“I’m thrilled with how well it’s turned out,” Betts says. “It has far exceeded my expectations.”

Betts’s research, conducted with Luther juniors Anna Luber and Linh Luong, focused on two mounds on private land near the Mississippi River, about 45 miles east of Decorah. Their study has historical roots in both past mounds research at Luther and in the funding for that research. Betts says this exploration is an extension of work that former Luther anthropology professor R. Clark Mallam did in the 1970s and ’80s. Among other things, Mallam and his students outlined effigy mounds in northeast Iowa in powdered limestone and took aerial photographs in hopes of identifying patterns among the mound groups. Coincidentally, the bird mounds that Betts’s group began researching this summer are the first mounds that Mallam studied.

Rare undergrad experience

Betts hopes to be able to see patterns in the data he collects from inside and around the mounds. The team used a gradiometer, measuring changes in the magnetic field, and a resistivity meter, which determines soil density by measuring its resistance to electrical currents. Later, Betts will also employ ground-penetrating radar. It’s rare for undergraduates to have access to this type of equipment, which Betts also teaches with during the academic year. “The number of schools in the United States that offer a dedicated undergraduate remote-sensing experience can maybe be counted on one hand,” Betts says. “But in some respects, this is where archaeology is going because we recognize [sites such as the mounds] are finite resources. When you dig, you destroy them.”

Anna Luber ’19 (far right), an anthropology major, experienced both kinds of archaeological exploration this summer. She joined Betts’s team immediately after participating in a traditional, invasive dig at Caesarea, in Israel.
Anna Luber ’19 (far right), an anthropology major, experienced both kinds of archaeological exploration this summer. She joined Betts’s team immediately after participating in a traditional, invasive dig at Caesarea, in Israel.

Another, perhaps even larger issue for the effigy mounds, Betts says, is that many are burial sites and all are sacred areas for Native Americans. “I had to clear this with the State Archaeology Office, which has an Indian Advisory Board,” Betts says. Remote sensing is the only way research can be done—nothing can physically penetrate the ground— and Betts knows of no one else doing such work on the mounds.

A history of grant help

The gradiometer was purchased through an endowed Anthropology Department collections fund and an equipment fund bolstered in recent years by donations from Harvey Klevar, professor emeritus of anthropology. The resistivity meter and ground-penetrating radar equipment were funded by grants from the R.J. McElroy Trust and the Kinney-Lindstrom Foundation, Inc., two Iowa-focused foundations with a history of assisting learning at Luther.

This aerial photo of bird mounds outlined in powdered limestone was taken during R. Clark Mallam’s research in the 1980s. In outlining mounds, he was looking for patterns among different groupings of mounds.
This aerial photo of bird mounds outlined in powdered limestone was taken during R. Clark Mallam’s research in the 1980s. In outlining mounds, he was looking for patterns among different groupings of mounds.

The McElroy Trust granted the funding for the resistivity meter, plus a bit more, as a challenge. McElroy encouraged Luther to leverage its grant to seek the rest of the funding for the ground-penetrating radar from other sources—to ensure that Luther was able to get all of the necessary equipment. So Jeanie Lovell, who oversees corporate and foundation support for Luther, contacted another Iowa foundation, Kinney-Lindstrom. The foundation’s past president, Lowell Hall ’56, was also a Luther regent emeritus. His son, Kent Hall ’81, is currently the treasurer and a trustee on the Kinney-Lindstrom Foundation board. The foundation had funded some of the work done by Mallam and recognized that Betts’s research continues those studies. An Iowa State Historical Society grant provided for additional GPS equipment.

Data turns into fascinating images

Three decades after Mallam’s project, Colin Betts is looking into the interior of the same bird mounds using remote-sensing equipment. This image is compiled from data taken from Luther’s new gradiometer, which measures magnetic fields in the soil. These images reveal two-toned wings on the birds, especially noticeable in the bird wing on the far right side. That raises questions about whether the wings were constructed of different types of soil and if so, why. Also visible in the magnetic data images are dots in which the top part of the dot is dark and the bottom is light. Those indicate dipoles, spots that have both negative and positive charges. Betts finds it interesting that the dipoles appear at the ends of the wings and in the center of the larger bird. He’ll be investigating whether similar dipoles appear in other mounds.
Three decades after Mallam’s project, Colin Betts is looking into the interior of the same bird mounds using remote-sensing equipment. This image is compiled from data taken from Luther’s new gradiometer, which measures magnetic fields in the soil. These images reveal two-toned wings on the birds, especially noticeable in the bird wing on the far right side. That raises questions about whether the wings were constructed of different types of soil and if so, why. Also visible in the magnetic data images are dots in which the top part of the dot is dark and the bottom is light. Those indicate dipoles, spots that have both negative and positive charges. Betts finds it interesting that the dipoles appear at the ends of the wings and in the center of the larger bird. He’ll be investigating whether similar dipoles appear in other mounds.

Betts, Luber, and Luong spent two warm, humid weeks in July gridding the grassy mounds with yellow cord and moving the resistivity meter and gradiometer systematically over the surface. The collected data was fed into a software program back in Betts’s third-floor Koren office, where the researchers manipulated it to create images of what’s under the earth.

The goals of this ongoing research are to see how well-preserved the mounds are, to get an idea of their interior structure, and to see what areas outside of the mounds may be important as ritual components. After only a few weeks of research, the team found several unexpected images that raise new questions. Magnetic spots, called dipoles, seem to appear in intentional spots—could they have been caused by ritual fires? The largest bird’s head appears to be looking to the left, which can’t be seen in Mallam’s photographs. A border that includes a triangle around the large bird’s head, not visible to the naked eye, also shows up. And the large bird’s wings appear two-toned in the gradiometer readings—could they have been constructed of two different types of soil? Why?

Data compiled from the resistivity meter can help determine the scope of the mounds and how well they have been preserved. For instance, the larger bird’s head appears to curve slightly to the left, and perhaps it is meant to be looking that way. That detail is not apparent in the earlier limestone outlines. Areas of less soil resistance appear as light spots in the bird. The light spot in the center of the large bird’s body is a looter’s pit, Betts says. The soil in that place is still indented from the digging. He doesn’t know yet what the other spots may be. Lines running over the large bird’s left wing are paths created by cattle that once grazed on the mounds. But the light-colored line that extends up from the left wing is a mystery so far. This image also shows that the mound had an outline—whitish areas around the birds— that formed a triangle around the large bird’s head.
Data compiled from the resistivity meter can help determine the scope of the mounds and how well they have been preserved. For instance, the larger bird’s head appears to curve slightly to the left, and perhaps it is meant to be looking that way. That detail is not apparent in the earlier limestone outlines. Areas of less soil resistance appear as light spots in the bird. The light spot in the center of the large bird’s body is a looter’s pit, Betts says. The soil in that place is still indented from the digging. He doesn’t know yet what the other spots may be. Lines running over the large bird’s left wing are paths created by cattle that once grazed on the mounds. But the light-colored line that extends up from the left wing is a mystery so far. This image also shows that the mound had an outline—whitish areas around the birds— that formed a triangle around the large bird’s head.

The mounds now appear more detailed than expected, and at this point, the data raises more questions than answers. These are all things that Betts’s research teams will look for in other mounds in future months and years to see if there are patterns. Each bit of information adds to an overall understanding of the ancient mounds and the people who built them.