Karen Royce

The Ohio State University

N'omi Greber

The Cleveland Museum of Natural History
Ohio Archaeological Council © 2001

The High Bank Earthwork (33RO24) is located in Ross County, Ohio on the east side of the Scioto River southeast of Chillicothe. The earthwork was mapped in 1846 by E.G. Squire and E.H. Davis (Squire and Davis 1848:Plate 16). A circle and an octagon joined by two short parallel walls comprise part of its complex design. Today the earthwork walls are severely degraded, primarily due to agricultural causes and continued erosion. Geophysical methods have been used at the site since 1994 (Figure 1:Blocks A through I) as a non-destructive means for delineating and studying the large circle in conjunction with very limited coring and excavation.

Figure 1. High Bank Earthwork 33Ro24, areas investigated 1994-2000
Figure 1. High Bank Earthwork 33Ro24, areas investigated 1994-2000

The focus of this year's field investigation was the portion of the large circular structure on land owned by the Archaeological Conservancy. The fieldwork objective was to complete a magnetic map of the circle and evaluate whether geophysical methods can be used to delineate structural qualities of the wall as recorded in test excavations (Figure 1:TI, TII). To this end, fifty 20-meter by 20-meter grids were traversed using a Geoscan FM-38 fluxgate gradiometer (Blocks J through Q).

The interpretation of the magnetic data was facilitated by the sharp contrast the circular wall has with the surrounding soil. For the most part, the wall is consistently 8 to 10 m wide. Five unique anomalies were observed in the data, two are interpreted as being historic (i.e., metal) and the other three as probably prehistoric. Two of the latter are subtle in appearance and generally oval in shape. They are located in the southeast portion of Block M and north central portion of Block P. It is interesting to note that the location of the anomaly in Block P is directly across from the neck where the circle and octagon join one another. The third likely prehistoric anomalous area is in Block J where a break occurs in the magnetic readings. This could be an opening in the wall that was noted by Squire and Davis in 1846.

Construction differences in the wall recorded in the test excavation, if present in other sections, are difficult to interpret with current data. In general, the outer limit of the wall appears to have a stronger magnetic signature than the inner edge. This can be due to differential weathering of the wall (and thus differential magnetic susceptibility of the soil); it could also be due to different soils and gravels of the inner and outer portions of the wall as seen in previous test excavations TI and TII. Further data collection is necessary to definitively determine the source of the differing magnetic signals from the wall edges, and the source of the anomalies.

The fieldwork and analysis were sponsored in part by a Laub Foundation grant to the Cleveland Museum of Natural History and a matching grant from the National Park Service. We thank the Conservancy and their farmer, Mr. Paul Esterday for access to the alfalfa field, Dawn Walters, staff member of Hopewell Culture National Historical Park, for assistance in the field, and HCNHP for support in many ways.

References Cited

Squire, E.G., and E.H. Davis
 1848  Ancient Monuments of the Mississippi Valley. Smithsonian Contributions to Knowledge 1. Washington, D.C.