Hiwassee Island Revisited: Using Non-Invasive Technology to Evaluate Archaeological Sites on TVA Land

30 Days of Tennessee Archaeology 2016, Day 28

Erin Pritchard 
Tennessee Valley Authority

 As a federal agency, the Tennessee Valley Authority is responsible for the identification and evaluation of archaeological sites on its managed lands under the National Historic Preservation Act. Over the last several decades the agency has surveyed many thousands of acres of land and identified over 11,500 sites on its property. A majority of the public land managed by TVA is located along the Tennessee River and its tributaries where people have been settling for thousands of years. The task of completing TVA’s inventory while simultaneously evaluating and ensuring the protection of these many thousands of sites has been incredibly challenging.

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Shawn Patch (New South Associates) talks to Emman Spain (Thlopthlocco Tribal Town) and Pat Ezzell (TVA Historian and Tribal Liaison) about ground penetrating radar.

With the significant depth of archaeological deposits along the Tennessee river (sites documented as deep as 12-15 feet below the surface), traditional survey methods are not typically effective for full identification of both horizontal and vertical sites. Coupled with that are ever-expanding problems with curation of archaeological collections. Repositories are running low on space, and federal agencies are struggling to pay for long term curation costs and material continues to come in. Agencies such as TVA must find more innovative and efficient ways to address these federal obligations.

Toward that goal, TVA has been exploring new technology to document archaeological sites. In the last few years, the agency has experimented with non-invasive geophysical techniques to survey TVA parcels. This methodology has proven to be most effective in the reexamination of previously recorded sites with limited known archaeological information, some not having been thoroughly examined since the 1930s and 40s when they were first discovered. A most recent example of these investigations was done at Hiwassee Island.

Hiwassee Island, located at the confluence of the Hiwassee and Tennessee Rivers in Meigs County, Tennessee, was initially visited as early as 1885 with numerous excavations over the next century including work by John W. Emmert (1885), Clarence B. Moore (1913-1914) and Mark Harrington (1919). These early explorations identified as many as 24 mounds on the island. Most of these earlier excavations focused on the conical mounds now known as Hamilton burial mounds.

WPA/TVA Archaeology Photographs, 1930's - 1940's

WPA workers at Hiwassee Island (Photo courtesy of McClung Museum of Natural and Cultural History)

The largest excavation conducted at Hiwassee Island occurred in the late 1930s when the University of Tennessee investigated the site prior to the inundation of Chickamauga Reservoir. Labor for this effort was provided by the Works Progress Administration (WPA). The focus of the excavation was on the Mississippian Village located on the north end of the island. Among the findings was a central plaza, palisade/stockade and large platform mound. Information collected from these investigations provided one of the first regional chronologies in the Southeast and the fieldwork and most importantly the resulting report was touted by numerous professionals in the field as being innovative for its time.

WPA/TVA Archaeology Photographs, 1930s-1940s

WPA Excavations of large platform mound on Hiwassee Island (Photo courtesy of McClung Museum of Natural and Cultural History)

Since the 1930s several small scale surveys and excavations have been conducted at the site. A reconnaissance survey in 1987 re-examined previously identified features, such as shell middens and mounds, still remaining on the island. An archaeological field school conducted between 1997-1999 assessed the extent of intact deposits along the shoreline as justification for stabilization to protect eroding features. While both of these efforts provided data to indicate the potential for remaining significant archaeological deposits, no comprehensive assessment of the island was made until 2015.

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Marianne Shuler (TVA Archaeologist) learns how to use the gradiometer

In 2015 TVA hired New South Associates to conduct a geophysical survey of the island to provide comprehensive data on the extent and nature of archaeological deposits to help support its nomination for the National Register of Historic Places (NRHP) and provide TVA with information to better manage the resource. Under the direction of Shawn Patch and Sarah Lowry, New South Associates conducted an initial magnetic gradiometery survey across the island and a ground penetrating radar survey in areas where the magnetometer identified potential archaeological features. In addition, conductivity and magnetic susceptibility data were collected by Eileen Ernenwein from East Tennessee State University. The fieldwork also included a week of training for TVA and other regional archaeologists and Federally recognized Indian tribal representatives to learn more about how this new technology works.

Geophysical results clearly indicate the island retains significant archaeological deposits. A total of 649 anomalies believed to be cultural features were identified in either the GPR or gradiometer data. These include middens (39), structures (129), pit features (356), palisades or portions of palisades (26) and historic homesteads (13). While resources were identified across the island (both prehistoric and historic), data collected from the previously identified Mississippian component on the island was included some of the more exciting finds associated with the project.

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GPR and gradiometer data results from Mississippian Village

As expected, the Mississippian village area of the island contained the highest density of archaeological features which included burned houses, middens, pit features and evidence of palisades. More specifically, results indicate that at least seven palisades once stood around the Mississippian town. One of these clearly defined palisade wall features includes what appear to be bastions. Excavations conducted during the WPA period identified at least one palisade, but now it appears that the Mississippian village expanded and/or contracted numerous times throughout its occupation. The time frame for these additional palisades cannot be determined through geophysical testing, so more testing is needed to establish a chronology.

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Interpretive results of Mississippian village.

Geophysical survey of Hiwassee island proved to be a successful method for providing TVA with the information needed to justify the site’s inclusion in the NRHP. In fact, the State Review Board of the Tennessee Historical Commission unanimously accepted Hiwassee Island as eligible for listing in the NRHP on September 14th. TVA hopes to see the site officially listed by the end of 2016!

More importantly, the work that has been conducted through these non-invasive methods has provided the agency with data that will help them manage archaeological sites on its land more effectively in the future. This methodology will allow the agency to evaluate and protect these resources without having to face large amounts of new archaeological collections or impact sensitive features such as burials. Once a site is excavated it is gone forever. Non-invasive technology allows archaeologists to collect sufficient data to limit our need for extensive excavations, so we are doing archaeology smarter and protecting these resources for many generations to come.

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