High Bank Site
Excavation of the Great Circle Wall at High Bank Works: 1997 and 2002
N’omi B. Greber
Curator of Archaeology
Map of High Bank walls by Squier and Davis
Aerial view of Circle and Octagon in 1938 |
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The High Bank Works (33Ro24) are located southeast of Chillicothe on a glacial outwash terrace about 17 meters above the active flood plain of the Scioto River. They are one of the more complexly designed sets of enclosures among the numerous enclosure sites found in the Central Scioto region.
The major sections include a relatively rare octagonal enclosure, small and large circular features, and linear walls. Field work in 2002 continued studies centered on the Great Circle as part of long term research aimed at placing enclosure sites into the context of both other types of structural remains such as buildings and mounds, and the well known artifacts.
Since 1994 a combination of geophysical surveys and limited excavation and coring has produced details of the design and construction of the Great Circle wall.
Two major goals were set for this past season and both were met. The first was to determine the source of an anomaly identified by both magnetic and resistance surveys in a small section of the wall directly across from the center point of the neck joining the Circle and Octagon. In an idealized ground plan, this point is a natural end for a line that would bisect the circle and the octagon. It also is a significant point in the astronomical design criteria proposed by Ray Hively and Robert Horn that may have been used in constructing the walls (Hively and Horn 1984). The second goal was to recover materials appropriate for radiocarbon assays. The nineteenth century farm lane that cut across the Circle and Octagon has been expanded for use by modern trucks and other vehicles. This has severely impacted the westerly side of the neck joining the two major enclosures and portions of these enclosures.
In 1846 the Great Circle wall, that had already been affected by farming, was still 1.4 meters (4-5 feet) high (Squire and Davis 1848:50). Today, at ground level it is difficult to impossible to visually trace the entire wall. It is easier using remote sensing techniques. Almost the total length and portions of the interior have been surveyed using a variety of geophysical instruments. The geophysical maps have identified erosional wash and the inner and outer edges of the wall itself that appears to originally been about 8 meters across. The geophysical anomaly investigated this season was first identified in 2000 using a fluxgate FM36 gradiometer. Surveys with the same instrument in 2001 and 2002, and resistivity pseudo-sections taken using the Geohm C earth resistance meter in 2001 corroborated the location and pattern of the anomaly. This pattern contrasts with the patterning of the general wall construction design (Greber 1999, Royce and Greber, 2001). A 2 m x 18 m trench was placed perpendicular to the wall in the central area of the anomaly that is generally circular in outline and approximately 14 m across. The northwesterly corner of the trench was at N 253.88, E -71.42 in the general site grid. Nine 2 m x 2 m excavation units, numbered north to south, were established. Excavations and backfilling took place from 17 June through 17 July.
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Excavation Findings
An unexpected finding is that more than 200 of the recorded features are apparently re-filled post holes of varying diameters. There is no obvious pattern in their locations. It is likely that other post holes exist outside the excavated area. The excavations also revealed the remnant of the wall itself and a different sequence of construction from that found in either of the two test trenches placed near the neck south of the farm lane (Greber 1999: Figs 4,5). Consistent with the initial construction seen in both Trenches I and II, the aboriginal site users apparently cleared the ground surface to about twenty cm above the underlying natural glacial sandy gravels. The clayey nature of the cleared B-horizon makes a usable activity floor that is a common Ohio Hopewell feature as seen, for example, at Seip in the structures excavated by the Ohio Historical Society and in the nearby plaza area (Greber, Otto, and Lee 2002, Greber 1981,1984). The specific activities associated with such prepared floors vary. At the High Bank Great Circle, numerous posts were placed on the floor found in Trench III. Shortly thereafter they were apparently removed and the holes filled with soils of the same type as those that formed the floor itself. Thus, it was extremely difficult to identify the post holes when the floor stratum was first exposed. Such re-filling is also a relatively common Hopewell feature, but the post holes are more easily recognized when fine gravels, colored clays, or other more contrasting materials are used as seen, again as examples, in the Edwin Harness Big House, on the floor under Mound 2 at the Hopewell Site, or in post holes found under Capitolium Mound, Marietta (Greber et al 1983, Greber and Ruhl 2000:55, and Greber 1991 respectively). In our work this past season, the post holes were very easily identified as soon as the natural gravels were reached. The origins of the posts can be seen in wall profiles.
Flagging floor features in Unit 3
Northwest section of Unit 1 showing post molds
Close-up of post molds on Unit 1 floor
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The original construction in this wall section included a slide trench smaller in scale than that found in Trench II (Greber 1999:Fig 5). A line of small decayed posts crossed the northerly end of the excavation near the outer edge of the Great Circle wall. The posts ended in the underlying natural gravels. The separate covering over this feature was truncated by the plow zone. A mantle composed of a layer of heavy gravels in a clayey matrix had been placed on the original activity floor. Infrequently small areas of redden soils and/or burnt pebbles were found in the loadings that formed this stratum, but no evidence for in situ burning was found. One large post intruded into the top of this stratum and possibly a line of shallow post holes near the inner edge of the Great Circle wall. The first stratum of the wall itself, found immediately below the plow zone, was a reddish sandy clay placed over a portion of the gravelly layer. The southerly end of this stratum indicates the inner edge of the Great Circle wall and appears to correspond to a change within the pattern of the geophysical anomalies.
Studies are continuing to work towards identifying the correspondence between the ground truth data and specific elements of the pattern of the anomaly for possible use in interpreting future geophysical surveys. Due to the lack of contrast between the materials of the floor and the re-filled post holes there is not, to my knowledge, a currently available geophysical survey instrument that would detect such features. A contrasting fill, particularly one that contained burned materials or fired ceramics, would provide a better target. The mantle materials, even those that are redeposited unaltered sub-soils and gravels, can provide more contrast with the ground areas immediately surrounding the walls. These are the types of signals we hope to clarify.
Radiocarbon Dates
Three AMS radiocarbon assays have been completed. Two dates, Beta 170562 and Beta 170564, come from bits of charred oak recovered from the slide trench (Feature 2) and are consistent with the dates obtained from the larger charred oak posts that composed the dismantled fence found in Trench II (Greber 1999: Table 1). The average at two sigma for the dates based on the small line of posts in Trench III is 1860 +/- 80 Years BP. Averaging the date based on charcoal from an above ground section of the dismantled fence and the three dates from the in situ below ground posts found in Trench II gives the same date. The third date, Beta 170563, is apparently not associated with the Hopewell wall construction. It was based on charred oak bits found at the edge of a post hole directly north of the slide trench (Feature 6). Beta Analytic conducted a second independent run based on materials selected from the remaining pretreated portion of the sample. The resulting date is the same, many millennia before the Hopewell era. Feature 6, a post hole that originated on the activity floor, contained a humic soil (7.5 YR 3/4, dark brown).
Window trench centered on west half of Feature 2
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It tapered downward some 40 cm deep into the underlying natural gravels. Tiny flecks of charcoal occurred in parts of the fill. The charred wood found on the activity floor at the edge of the post hole appears to have been the remains of some earlier use of the site. The only portable artifact recovered this season, is a small, burnt, worked flint flake that was probably an accidental inclusion in the soils used for wall construction. It is possible that a second accidental inclusion of charcoal bits occurred during Hopewell earth moving. Unfortunately, Beta 170563 is not useful for dating the original building time of the Great Circle wall.
Comments
It must be kept in mind that the following comments are based on a very small excavation sample of the wall. The six usable radiocarbon dates from essentially opposite sides of the circle suggest a relatively short time, in terms of human generations, for initial construction of the wall. This is consistent with the condition of the lower strata found in Trenches I and II where about thirty percent (40 centimeters) of the wall height recorded in 1846 is still intact. Here the top surfaces of the inner “red” and outer “yellow” base strata showed no signs of exposure. The total construction time that left a significantly higher wall is still not known. Edges of the upper layers and two erosional episodes, apparently before and after AD 1800, were seen in Trenches I and II. The materials used to form the “red” stratum near the neck and also to re-fill post holes on the opposite side of the circle, likely came from a horizontal stripping of the pre-Hopewell natural ground surface. Dan LeMaster, Regional Soils Specialist, Soils Conservation Service has found evidence for this stripping in his observations of the present ground surface within the circle (p.c. 1997, 2001, 2002). Such stripping was also clearly documented beyond the inner edge of the original circle wall at the southerly end of Trench III.
Prior to wall construction appropriate Hopewell architects and engineers determined a ground plan, wall design, and construction techniques. Prior to raising the wall, activities took place at the site that emphasize the importance of the initiation of the building process, and perhaps of the planning phase. At least some of these activities could have been seen by those carrying the required special soils and gravels that they deposited, each in their proper arrangement. The remains of the ritual activities found at the base of the wall differ near the neck and across the circle from the neck. None of the portable objects used in any associated activities have been found. The plethora of posts adds new, and as yet unexplained, elements to possible interpretations of the range of pre-construction activities.
Acknowledgments
Permission for the excavation came from the United States Department of the Interior and Hopewell Culture National Historical Park. Funding was provided by the Robert M. Utley Research Fund, the Laub Foundation, the NPS Challenge Cost Share Program, and Hopewell Culture National Historical Park. Services in kind came from Hopewell Culture National Historical Park, the Midwest Archaeological Center, Hocking College, and the Cleveland Museum of Natural History.
References
Greber, N’omi B.
1981 Salvaging Clues to a Prehistoric Culture. The Gamut 3:22-45. Cleveland State University.
1984 Geophysical Remote Sensing at Archaeological Sites in Ohio: A Case History. Paper presented at the Annual Meeting of the Society of Exploration Geophysics, Atlanta. Published in volume of the proceedings.
1991 Preliminary Report on the 1990 Excavations at Capitolium Mound, Marietta Earthworks, Ohio. Presented to The National Geographic Society, Washington, D.C., 1991
1999 Combining Geophysics and Ground Truth at High Bank Earthworks, Ross County, Ohio. The Ohio Archaeological Council Newsletter 11(1): 8-12.
Greber, N’omi, editor
1983 Recent Excavations at the Edwin Harness Mound, Liberty Works, Ross County Ohio. Special Paper No. 5, Midcontinental Journal of Archaeology, Kent State University Press.
Greber, N’omi B., Martha P. Otto, and Anne B. Lee
2002 Revisiting the Structures Recorded Within the Seip Earthworks, Ross County, Ohio. Paper presented in 3 October Plenary Session, Midwest Archaeological Conference, 3-6 October, Columbus.
Greber, N’omi and Katherine C. Ruhl
2000 The Hopewell Site: A Contemporary Analysis Based on the Work of Charles C. Willoughby. Eastern National, Washington, PA.
Hively, Ray and Robert Horn
1984 Hopewellian Geometry and Astronomy at High Bank. Supplement to Volume 15, Journal for the History of Astronomy: S85-S100.
Royce, Karen and N’omi B. Greber
2001 The Year 2000 Field Season at the High Bank Earthwork. The Ohio Archaeological Council Newsletter 13(1):23.
Squier, Ephraim G. and Edwin H. Davis
1848 Ancient Monuments of the Mississippi Valley. Smithsonian Contributions to Knowledge 1, Washington D.C.
To read more about work at High Banks, go to: http://www.cr.nps.gov/mwac/hopewell/v6n2/three.htm