Sunday, April 24, 2011

Summer 2011 Archaeological Field Schools at OHS

In addition to its world-class archaeology, natural history and history collections, the Ohio Historical Society is steward to a statewide system of prestigious historic and prehistoric sites - second only to the National Park Service in type and variety of locations. Among the more notable of OHS properties are Fort Ancient in Warren County and the Johnston Farm and Indian Agency, formerly known as the Piqua Historical Area, in Miami County.

This summer significant archaeological research will be undertaken at both places to better understand the sites' purpose and function and/or events that occurred there in the past. Field work is particularly labor intensive and it is often the case that it is preformed during the summer season by college and university students, under their instructor's direction. Many hands make the work go faster. Summer schools offer both a foundation in the discipline of archaeology for the students and a chance for the Ohio Historical Society to learn more about their holdings.

Fort Ancient Field School Uncovers Ancient History

Fort Ancient in Warren County is a hilltop enclosure consisting of nearly 3.5 miles of earthen walls that range from 4 to 23 feet in height. They encircle a high bluff above the Little Miami River near Oregonia. The earthwork walls are broken by more than 80 irregularly spaced gaps or "gateways," the purpose of which is not particularly well understood. Fort Ancient was constructed approximately 2,000 years ago by the Hopewell culture.

In 2004, OHS received a Save America's Treasures grant to do erosion control and restoration at various locations throughout the site. Preliminary to actual construction, affected areas were surveyed with geophysical instruments designed to see what might be located below the surface in a given area without actually having to dig exploratory excavations. The results come back as sub-surface anomalies that can be individually investigated.

In 2005, a series of anomalies in the northern portion of the site turned out to be perhaps one of the most significant discoveries of its type in the past several decades. The geophysical data indicated there was some sort of very large pit feature with a very high magnetic signature at the center of what appeared to be a 200-foot diameter wooden-post enclosure, or henge, with a single out-turned opening or gateway just a few degrees off from due south. Inside the henge there are at least two of what was been interpreted as house structures or perhaps ceremonial floors.

In 2006, Dr. Robert Riordan, students from Wright State University and selected volunteers began an ongoing investigation of what became known as the Moorehead Circle, named in honor of Warren King Moorehead, former curator of archaeology at the Ohio Historical Society and an early investigator of Fort Ancient. In fact, it was largely through his efforts that the state legislature was made aware of the site's importance and Fort Ancient being set aside as Ohio's first archaeology reserve.

The past field seasons at Fort Ancient have revealed that the large central pit was filled with soil burned at a high enough temperature to turn it bright brick red. However, it appears that it had been burned at some other location, scooped up and gleaned of any foreign material, including charcoal, and redeposited in the pit at the center of the circle. Surrounding the central-pit feature is a shallow ring-shaped feature that contains a sizeable number of pottery fragments and small flint artifacts. The henge that surrounds the site was tested in two places and it was found that the posts used in its construction were of a large diameter (up to 12 inches) and placed with fairly regular spacing. Most were deeply set and held in place with up to 200 pounds of stone chinking. The slip trenches used to erect the posts, their large diameters and the amount of stone needed to hold them in place indicates that the posts were likely of a telephone-pole size - architecture on a truly monumental scale.

Work on the interior of the circle begun last year and continuing at present indicates a single large or complex set of smaller limestone slab plazas inside the south side of the circle possibly associated with the supposed house structures. To complicate things even further, it would appear that these plaza features were cross cut by a series of shallow, squared trenches some time after their original construction.

What does it all mean? It is far too early to connect all the dots, so to speak, and it will probably take many more field seasons of work to make a correct interpretation. An area of nearly 35,000 square feet and working just a few weeks a season makes work to understand the Moorehead Circle slow going.

For more interesting topics related to archaeology, visit archaeology excavations.

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