Friday, November 11, 2022

A Summary of the Eastern States Rock Art Research Association’s 2022 Conference

The Eastern States Rock Art Research Association (ESRARA) held its 2022 conference on Oct. 7-8, 2022, in St. Louis, Missouri. The conference brought together presenters and attendees from nine states to discuss the documentation, preservation, and interpretation of rock art sites which included petroglyph (images carved on stone) and pictograph (images painted or drawn on stone) sites in the Eastern United States. Pennsylvania was well represented with three presentations focusing on rock art sites from the Keystone State, which now has over forty petroglyph sites recorded in its cultural resource site files.

The logo for the Eastern States Rock Art Research Association (ESRARA).

A theme throughout the conference was that rock art sites often go unnoticed unless someone is looking for them. One of the presentations focused on Pennsylvania included images and discussion about seemingly forgotten sites and another previously undocumented petroglyph site in the Lower Susquehanna Valley. Located atop a small rock island in the river is carved the figure of a birdman that was previously unknown to researchers.

A figure with both human and bird-like attributes is carved on the highest section of a small rocky island in the Lower Susquehanna River. (Photo: Melanie Mayhew)

As digital technologies advance so do methods for documenting petroglyph sites. Several presentations at the conference demonstrated the use of 3D modeling using photogrammetry and LiDAR. Photogrammetry software uses images to construct a 3-dimensional model while LiDAR uses specialized equipment to collect data with a laser. A benefit of photogrammetry is that no specialized equipment is needed to collect the data, just a digital camera. Photos are then imported into photogrammetry software and a 3D model created. Unlike archaeological excavation, which is a destructive process, the study of rock art primarily uses non-destructive methods of documentation, and it promotes the preservation of sites where they were created hundreds or even thousands of years ago. 

This birds-eye view of a well-known petroglyph site in the Lower Susquehanna Valley was created by linking many images into a 3D model using photogrammetry. While this view is useful for mapping a site, it is not an angle from which the site can be easily viewed in real life. (Image: Melanie Mayhew)

Presenters also discussed new methods of illustrating sites using digital technologies. Referencing the same site as the 3D model above, the image below was created by digitally tracing a high-resolution photograph of the site using a Wacom drawing tablet and Adobe Photoshop. Drawing a site in this format provides a comprehensive method of visualizing subtle detail that has been excluded from previous attempts to map petroglyph/pictograph sites. It also gives the viewer a realistic view of the site at a specific time of day and year. Methods of mapping sites using such media as chalk or other substances are not recommended by conservators.

An original photograph taken during sunrise around the equinox (left) and the illustration created by digitally tracing the photo (right). (Images: Melanie Mayhew)

Pictographs (images drawn or painted on stone) are most often associated with western states, but one was recently rediscovered and documented in Pennsylvania. The Chickaree Hill Pictograph is a relatively small circular image drawn on the ceiling of a rock overhang in western Pennsylvania. Its red color comes from the iron-rich material, likely hematite, that was used to create the image. DStretch, a digital tool available as an app, can aid in making faded or faint pictographs more visible. This tool has helped to increase the number of visible images on previously documented pictograph sites. 

A photograph of the Chickaree Hill Pictograph from Pennsylvania’s Archaeological Site Survey (PASS) form. The circular decorated area is only a few inches across. (image: PA-SHARE)

Among other presentations, the conference included a day-long field trip to Cahokia Mounds, an UNESCO world heritage site, and two nearby petroglyph sites. One of these sites, Washington State Park, provided caution against well-meaning infrastructure improvements that can damage a site over the long term, as seen below.

The above images of Washington State Park petroglyphs show the southern (left) and northern (right) panels at the site. The northern panel remains continuously shaded by a boardwalk and overhead shelter, providing favorable conditions for organic growth which will, over time, damage the site.

For more information, visit the Eastern States Rock Art Research Association (ESRARA). For more information on Pennsylvania Petroglyphs, view our petroglyph brochure (PDF).

Links and Resources:

American Rock Art Research Association (ARARA)

ARARA is an active community dedicated to rock art preservation, research, and education. Several educational resources can be found on their website, including lesson plans for grades K-9. ARARA hosts frequent web presentations and holds an annual conference. Past web presentations can be found on their YouTube channel.

Eastern States Rock Art Research Association (ESRARA)

ESRARA is a group of dedicated professional and avocational members who focus their attention on rock art located in the Eastern United States.

Society for Pennsylvania Archaeology (SPA)

A community of professional and avocational archaeologists dedicated to the scientific study and conservation of archaeological resources in Pennsylvania and surrounding states. Their 92nd annual conference will be held in Dubois, Pennsylvania on April 14-16, 2023.

Burkett, Ken

2021 The Chickaree Hill Pictograph (36CB28). Pennsylvania Archaeologist. Vol 91(2)

Cadzow, Donald

1932 Petroglyphs [Rock Carvings] in the Susquehanna River near Safe Harbor, Pennsylvania, Safe Harbor Report No. 1. Pennsylvania Historical and Museum Commission, Harrisburg.

Swauger, James

1974 Rock Art of the Upper Ohio Valley. Akademische Druck, Austria.

For more information, visit or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .

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