Geophysical Survey at Ohio Earthworks: updating Nineteenth Century Maps and Filling the ‘Empty’ Spaces

Abstract

ABSTRACTThe state of Ohio is rich in monumental architecture, from small, geometric ditch‐and‐embankment earthworks to wooden henge‐like enclosures and massive complexes consisting of miles of earthen embankments. Until recently, scholars have relied primarily upon nineteenth century maps and mound excavations for use in a range of research programmes related to the earthworks. However, large‐scale geophysical surveys are showing that most of the nineteenth century maps are inaccurate in a variety of ways. To many earthwork scholars perhaps most surprising are the new enclosures and other features appearing between the mounds in the geophysical data. This article explores the geophysical survey results from three sites in southern Ohio: Steel Group, Snake Den Group and Fort Ancient. A selection of magnetic gradient, electrical resistance and ground‐penetrating radar data are presented. The three sites examined represent a range of different earthwork site types, including floodplain enclosures, a large hilltop enclosure and hilltop mound clusters. The surveys from these sites also highlight the kinds of previously undocumented features that can be found during geophysical surveys at Ohio earthwork sites, including henge‐type wooden enclosures, ditch‐and‐embankment enclosures and pit‐type features. These results suggest that other Ohio earthwork sites, and earthwork sites in surrounding states, are probably more complex than previously thought. Although archaeologists have in the past 100 years attempted to look beyond the burial mounds for evidence of what these monumental sites were used for, the large size of the spaces between the mounds and enclosures has made it difficult to locate additional evidence. As in other regions of the world, geophysical survey in the Ohio valley is allowing archaeologists to create more detailed and accurate maps of monumental architecture sites, as well as to locate some of the smaller and more subtle features between the monumental constructions. Copyright © 2014 John Wiley & Sons, Ltd.