When an Iowa farmer discovered an enormous thigh bone on his property, it was the start of an amazing excavation that has yielded bones both large and small from at least two different species.
The farmer, who has chosen to keep his identity and the location of his farm private, called on the expertise of scientists at the University of Iowa and other institutions for help in recovering the woolly mammoth bones earlier this year. To date, they’ve uncovered more than 30 bones in the same area. This indicates the animal died near where the bones were found, allowing scientists to learn even more about how it lived and died.
Some believe it could be the most important mammoth discovery in Iowa.
IIHR Associate Research Engineer Frank Weirich has contributed to the excavation by imaging the entire site using ground-penetrating radar. Weirich, who is also an associate professor of geoscience/civil and environmental engineering, explains that the radar images help paleontologists know where and how to proceed, and whether to use an earthmover or a toothbrush — or something in between.
“They’re trying to figure out where to dig next,” he explains. Ground-penetrating radar makes use of the same technology as atmospheric radar, but aims it downward and changes the frequency. When configured as a multi-channel radar system, ground-penetrating radar can send and receive multiple frequencies simultaneously, providing data of relatively high resolution from different levels within the earth.
Weirich says they created a grid of the site and took both vertical and horizontal radar slices of the area. These data were rendered into a 3-D image. The information gathered this way gives researchers valuable information about what lies beneath the surface of the ground — where to dig, and where to use particular care.
Woolly mammoth finds are not unheard of in Iowa, but finding more than one species, and an entire skeleton, at one site is highly unusual. Woolly mammoths flourished during the glacial period in North America and Eurasia. As glaciers receded, some mammoths remained in the Midwest. They died out when the Ice Age ended about 11,000 years ago, due to a rapidly changing climate.
Sarah Horgen, Museum of Natural History education coordinator, says it also has enormous educational potential. “We are excited about the scientific research that will come from this site, but also about how we can use the excavation and research as an educational tool to show Iowans the natural history that is right under their feet.”
The UI-led excavation has involved partnerships with various institutions and local organizations, including William Penn University in Oskaloosa, Iowa State University, the Office of the State Archaeologist, and the Cedar Valley Rock and Mineral Society. High school teachers, students, and residents also have participated in the dig.
Weirich says the site is yielding significant finds, including the impressive femur, multiple ribs and vertebrae, and a few toe bones —and there’s likely to be more. “It’s huge,” Weirich says. “It may take another year.”