Miamisburg Mound, the largest conical earthwork in Ohio, originally was sixty-eight feet high with a diameter of three hundred feet. One excavating attempt in 1869 reduced the height to its present sixty-five feet. The mound was then partially investigated by means of a vertical shaft which extended from the top to the base and connected with two horizontal tunnels. The exploration revealed one burial eight feet from the top containing a bark covered skeleton and a vault twenty-eight feet lower that was surrounded by logs but without a burial. Along the sides of the vertical shaft were found various layers of ashes and stones, implying that the mound was built in several stages. The entire construction, however, has never been systematically excavated. The conical shape, the type of burials, and the absence of associate earthworks indicate that the Miamisburg Mound was the work of Adena Indians, a prehistoric group that lived in the Ohio valley between 1000 B.C. and 400 A.D. These people were the first in this area to domesticate plants for food, to settle in fairly permanent villages, and to make pottery. An important part of their way of life was the proper burial of the dead in graves that were covered with earth mounds, such as this one.