Steel Archaeology

The Steel Group

The Steel Group earthwork site is located at the southwest edge of Chillicothe, Ohio in a narrow valley cut by glacial melt waters at the end of the last ice age. It was first documented in the 1840s by Ephraim Squier and Edwin Davis in their landmark volume Ancient Monuments of the Mississippi Valley (Squier and Davis 1848). Their basic map of the site included two circles, with gateways facing roughly east, and a small nearby mound. Today the site has been severely impacted by plowing, and only the larger of the two circles is still visible to any degree.

Sq&D Middle Scioto Valley Steel highlighted 2

In 2007 and 2008 HEC President Jarrod Burks surveyed the site with a Geoscan Research FM 256 fluxgate gradiometer, a type of handheld magnetometer. Just prior to the magnetic survey, an oblique aerial photograph taken in early June 2007, with the winter wheat taking on a golden hue as it matured, revealed a number of additional possible enclosures not previously documented in the Squier and Davis map.
The magnetic survey confirmed the presence of the additional enclosures from the aerial photos, as well as several more. The magnetic data in Figure 2 were collected at a density of eight readings per meter along transects spaced one meter apart. The darker geometric shapes in the data are the magnetic signatures of the enclosure ditches, all but the largest of which has been completely filled by nearly 200 years of plowing. The foundations of most of the enclosure embankments, now plowed away, are visible as less magnetic areas surrounding the ditches. The decreased magnetism associated with the embankments is likely the result of near-surface clayey subsoil used in constructing the embankments; or it might indicate that the topsoil was removed prior to the construction of the embankments—topsoil is magnetic, so when it is removed it leaves behind an area of decreased magnetism.
Steel Simple-All Mag 2007
While the 19th century map of the site recorded two circles, clearly the site consists of one larger circle, seven small squircles (a shape part way between circle and square), a c-shaped enclosure, and one entirely unique shape (a small square with an open corner) not previously known in the middle Ohio River Valley. In addition to the two enclosures, two faint but distinctive circles of small anomalies are likely circles of posts, i.e., henges (see if you can find them!). One may be associated with one of the squircles as it is located directly outside and aligned to its gateway. The other henge-type feature overlaps with another of the squircles. Circles of postholes are commonly found under mounds in the region and are often associated with the Adena cultural manifestation. However, post circles have also been found under the embankments of circular enclosures and lining the inside edges of circular ditches.
Once considered a small and ephemeral site in an area extremely rich in larger earthworks (see Squier and Davis, 1848: Plate II), the 2007-2008 magnetic survey of the Steel Group has found it to consist of many more enclosures than once thought—some of which were not visible under fairly ideal conditions for aerial photography. These results certainly provoke many questions, especially about enclosure function and construction sequence. Does the variety of enclosure shapes indicate differing functions or change through time? And is the repeated appearance of squircles a sign of multiple groups using the site at the same time or one group building new enclosures of a similar function but over many visits? The appearance of the post circles was also unexpected, given the lack of mounds in these locations. Wood post enclosures may be more common at these earthwork sites than previously known, filling in some of the “empty” spaces between the ditch and embankment enclosures.

Find out more about the Steel Earthworks:

Conservation Plans for the Steel Group

Newly Discovered Ancient Earthworks at the Steel Group

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