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GPR Survey of an Inundated Paleoindian Site

TerraSearch Geophysical, in collaboration with the UConn Geosciences Department, is conducting an underwater ground penetrating radar (GPR) survey of an inundated Paleoindian site. The site, which was discovered in the 1990s and partially excavated by Dr. John Pfeiffer when the 19th century impounded lake levels were lowered, preserves evidence of a normal Paleoindian toolkit, including a broken fluted point base, several end and side scrapers, as well as utilized flakes. A three-dimensional reconstruction of an end scraper and the fluted point are shown below. These artifacts are currently on display at the Lebanon Historical Society, who graciously allowed us (and Dr. Zachary Singer previously) to photograph and reanalyze the collection.

3-D model of the bit end of an End Scraper from the Liebman Site
Fluted Point Base Recovered from the Liebman Site

Because the site is currently inundated, it is not possible to investigate the surrounding area through traditional archaeological methods. We instead set out to study the underwater portions of the site through GPR via small watercraft. This survey will be useful in contextualizing the geologic setting of the site, understanding the environmental characteristics that made the site attractive to people during the Paleoindian period. The survey was conducted via a paddleboard and small raft, using a GSSI 350 MHz Hyperstacking Antenna. We collected our data via time delay, and used an Emlid Reach GPS system to track our location. The data was collected via grid and wildcat, to make sure that we covered the entire area.

Andy Fallon conducting underwater survey of the Liebman Site
Andy Fallon conducting underwater survey of the Liebman Site

The results of the survey provided compelling geologic information about the sedimentation at the site. A relatively flat terrace is preserved above the original course of the river in our eastern profiles, which provides an ideal location for a Paleoindian campsite.

Eastern transect of Liebman Site Area
Eastern transect of Liebman Site Area

Additional profiles indicate that an earlier river channel also exists within the project area, but has been buried through successive flooding, indicating potential long term stability of the river, as well as deep burial of some site elements.

Western GPR Transect of Liebman Site Area
Western GPR Transect of Liebman Site Area

Finally, the survey was particularly useful in creating a high resolution three-dimensional bathymetric map of the existing pond floor, to help contextualize the site area. This three-dimensional reconstruction is shown below, with clear evidence for the existing river channel, as well as several areas that might have been attractive campsite locations for Paleoindians.

Bathymetric 3-D map of Liebman Site Area
Bathymetric 3-D map of Liebman Site Area

The data analyses of this survey are currently ongoing, but Andy Fallon, PhD student at the University of Connecticut, is planning to present the results of the survey at the upcoming Eastern States Archaeology Federation Meeting.