In 2014, an exciting discovery occurred in the initial spot identified for the visitor center when enormous images of mythic beings, called geoglyphs, were found beneath the upper layer of sod. Ancient peoples left these mysterious images between 2,000 and 1,500 years ago, long before Blood Run/Good Earth's settlement. Omaha, Ponca, and Ioway Tribal Historic Preservation Officers and archaeologists suspected their presence and supervised the investigation. Once the geoglyphs appeared, they were labeled, analyzed, photographed, and covered back up so that they could be preserved. Good Earth State Park is one of only three North American sites with geoglyphs, and the other two locations are in eastern Iowa. All three sites sit on high ground above rivers. The team investigating the geoglyphs estimated that the 3.5 acres they studied probably included about 140 drawings. No one knows for certain what the images illustrate, nor is their purpose known. Archaeologists dug a pit to learn more about how the images were made, finding that the darker line in the soil was the image, made by digging a trench about 12 to 18 inches deep, with the line a different color because the topsoil that fell into the trench was darkened by plant and organic matter.