Early and Middle Woodland Earthwork Enclosures in Iowa

Earthen enclosures are hallmarks of both the Early Woodland Adena complex and the Middle Woodland Hopewell Interaction Sphere of the eastern United States. Early and Middle Woodland enclosures also exist west of the Mississippi River, but these generally have been overlooked. Eastern Iowa has at least five enclosures of apparent Early or Middle Woodland affiliation and numerous others with later or undetermined affiliations. The Woodland enclosures contain many of the characteristics associated with Adena and Hopewell in terms of their size, apparent non-defensive function, and association with ritual areas including burial mounds. The distribution of these earthworks suggests that the Mississippi River valley was the western limit of Adena- and Hopewell-related ceremonial enclosures but that their importance may have extended more widely.