Advanced Technology “Rubs” the Ancient Past

With more than 400,000 visitors, the Pennsylvania Farm Show, held each January, is a terrific opportunity to highlight the best of Pennsylvania agriculture. It’s also an exciting venue to showcase Pennsylvania archaeology and remind the public that archaeological sites are important endangered resources that need protection.

Since 1980, PHMC’s Bureau for Historic Preservation and The State Museum of Pennsylvania have presented educational exhibits at the Farm Show. For the past ten years, PHMC produced the exhibits in cooperation with the Society for Pennsylvania Archaeology Inc. (SPA), the Pennsylvania Archaeological Council, and the Pennsylvania Department of Transportation. Each year, a committee consisting of representatives of these organizations selects a theme or a type of archaeological site upon which to develop an exhibit. Committee members decided to feature sites of Native American petroglyphs, or rock carvings, for the 2008 Pennsylvania Farm Show last January. They reasoned that fellow committee member Paul A. Nevin, of York County, SPA president, who has spent more than twenty-five years researching petroglyphs, could handily lend his expertise in this relatively unstudied area of archaeology.

Petroglyphs are images and symbols carved into the surface of natural rock. Native American designs include lines, dots, and human, animal, supernatural, and symbolic images. Petroglyphs are found throughout the world and date back tens of thousands of years. Although many think of “rock art” as existing chiefly in the American Southwest, Pennsylvania’s native peoples also left a legacy of stone carvings. Unlike those in southwestern states, which are often scratched through a dark surface of desert varnish to expose lighter underlying rock, most of the Commonwealth’s petroglyphs were created by chiseling the rock with harder stones or hammer-stones and stone chisels. Petroglyphs in Pennsylvania were usually carved less than three-eighths of an inch deep, and grooves making up their designs are less than an inch wide. Because they are so shallow and share the patina of the surrounding rock, they are difficult to discern.

Archaeologists assume that images and designs discovered at petroglyph sites were common in prehistoric societies. Many were likely portrayed in wood, basketry, and clothing and rarely survive in the archaeological contexts of eastern North America. Petroglyphs provide a unique glimpse of how prehistoric people interpreted and related to their world.

The Pennsylvania Archaeological Site Survey (PASS) currently records thirty-nine Native American petroglyph sites, the majority of which are located in prominent locations near water, especially large rivers. The images are found in clusters ranging from a few to groups of hundreds at a single site. Archaeologists have recorded twenty-eight sites in western Pennsylvania’s Ohio Valley, although most of these are represented by small groups of images. The lower Susquehanna River has yielded the largest concentration of petroglyphs in the northeastern United States with ten sites containing more than one thousand separate carvings. They were found within a twenty-three-mile stretch running through southern Lancaster County and dipping just below the Mason-Dixon Line into Maryland. Because of the construction of hydroelectric projects on this section of the river, many of the petroglyphs have been submerged or removed for preservation and study.

Petroglyphs are a form of symbolic communication and their messages were important. Archaeologists do know they are not a form of prehistoric graffiti, as had been widely believed. Carving in rock with stone tools required too much effort to be undertaken without serious intention. The locations for the carvings were probably important and possibly sacred prior to the placement of the images. They conveyed information – perhaps describing tribal boundaries, hunting grounds, or the people who lived in or passed through the region. The prominent river petroglyphs such as Big Indian Rock, Lancaster County, in the Susquehanna River, and Indian God Rock, Venango County, along the Allegheny River, are perhaps plausible examples of the boundary marker theory. Many, however, are not obviously visible from the river and must have had other functions. Some petroglyph sites may have been sacred places where people came to communicate with the supernatural or places where medicine men, or community or spiritual leaders, gathered to meditate to receive visions or guidance, or to lead or heal their people. Some of the symbols may have had special significance for hunting, fishing, or for solving family or tribal problems. Petroglyphs might have been used to teach young individuals about their culture and the world around them – similar to religious classes conducted throughout the world today. Some designs may represent animal or spirit “helpers,” or totems, that were received through a visit or a vision by a medicine man, or by an adolescent in a coming-of-age ceremony.

The largest concentration of petroglyphs in the northeastern United States survives just south of Lancaster County’s Safe Harbor Dam. The most famous of these sites, Big Indian Rock and Little Indian Rock, were first recorded in 1863 and later investigated by Donald A. Cadzow of the Pennsylvania Historical Commission in 1930 and 1931. A half-century later, in the 1980s, Nevin recorded additional petroglyphs on several other rocks in the vicinity. In 2002, SPA’s Conejohela Chapter 28 systematically recorded more than 300 petroglyphs on seven rocks along this stretch of the Susquehanna River.

One of the goals for the Farm Show exhibit was to present an image of the petroglyphs on Little Indian Rock. There was serious discussion about creating a life-size cast, but that proved too complex and prohibitively expensive. Instead, organizers decided to exhibit a rubbing of the carved images. Rubbings, often associated with recording grave markers, are a good, low-tech way to map petroglyphs. The idea was to convert the rubbing into a large-scale banner for the archaeology exhibit.

On a warm Sunday in mid-October, Nevin and Kurt W. Carr, senior curator of archaeology at The State Museum of Pennsylvania, loaded a small boat with gear and motored out to the site from just below the Safe Harbor Dam. Little Indian Rock is about forty feet in diameter and divided in half by a large crack with a tree growing from its middle that separates the upper half from the lower portion. The majority of the images are on the upstream half. The water level fluctuates because of periodic releases by the dam, but the rock usually stands about five feet above the river’s surface. Access to the rock is easiest on the downriver side, where the foundation of an old duck hunting blind exists. The upstream half is gently arched and contains more than one hundred images. Some are clearly evident, while others are only visible when the light is perfect.

Visitors to the site usually spend their first few minutes admiring the ancient artwork. With a little water splashed across the rock, the carvings seem to be three dimensional. To accomplish the rubbing, Nevin had ordered fifty-inch-wide archival DuPont™ Tyvek®, a type of paper barrier often used in modern building construction. He makes his own crayons, about the size of hockey pucks, by melting standard crayons and adding powdered dye so they produce a dark image without smudging. His crayons worked well until they began to melt in the sunlight and needed to be cooled in the shade.

Nevin and Carr rolled a twenty-foot-long section of paper across the lower portion of the rock and taped it down. In the 1930s, Cadzow had made drawings of the designs which Nevin refined by tracing and creating a photo-mosaic image of the petroglyph panel. The pair used this to guide the crayons, pressing hard in places where there were images and exerting only slight pressure where there were none. The first section of paper was on a downward slope, and Carr held on to Nevin to keep him from falling off the rock as he rubbed the images nearest to the water. The rock was rough and irregular in places, and many of the images were shallow. It was difficult to make all the images appear even though they could feel them with their fingers.

As Nevin and Carr rolled out a second and third stretch of paper, they painstakingly overlapped the images so that the sheets could be matched later when they were scanned to produce the banner. In about five hours, the two completed about 80 percent of the rock.

With Ted R. Walke, chief of PHMC’s Division of Publications and Sales, who wanted to document the project with photographs, they returned the following weekend to complete the rubbings. Reaching Little Indian Rock by boat, Nevin says, “has always been iffy.” When the Native Americans carved the petroglyphs, the rock was amidst an area of rapids. Today, Lake Aldred, formed behind Holtwood Dam – completed in 1910 as part of the Holtwood Hydroelectric Plant – submerges the rapids, but river conditions can make access difficult or impossible.

The experience of making the rubbing was insightful. Working on their knees, they observed – and felt – every detail of the rock. It was easy to imagine people in the distant past pounding on the rock and carving the designs.

Jeff Decker, an editor and designer with PHMC’s Division of Publications and Sales, digitized the rubbings with the assistance of Harry F. Parker, chief of the Division of Archives and Manuscripts, Pennsylvania State Archives, who retired in August. The result was an electronic reproduction of the Little Indian Rock petroglyphs. For the Farm Show, they were reproduced as a large banner, measuring twenty feet long and eight feet wide. The exhibit proved to be a successful public outreach effort. From a scientific standpoint, the electronic image will greatly facilitate the analysis of these petroglyphs.

Since 1980, Kurt W. Carr, coauthor of several books on archaeology, has been providing his expertise to the Pennsylvania Historical and Museum Commission (PHMC) and served as chief of the Division of Archaeology in the PHMC’s Bureau for Historic Preservation from 1988 to 2005. He has conducted extensive field work with interests that include early Holocene adaptations, lithic technology, settlement pattern analysis, geomorphology, and environmental reconstructions. He frequently lectures about anthropology at Harrisburg Area Community College. Currently the senior curator of archaeology for The State Museum of Pennsylvania, he is investigating a Paleoindian site in Dauphin County dating between 10,000 and 11,000 years ago.

Paul A. Nevin is president of the Society for Pennsylvania Archaeology. He has a background in education and is the owner of Paul A. Nevin Fine Carpentry & Restoration in Hellam Township, York County, specializing in historic restoration. He has studied petroglyphs on the Susquehanna River for more than twenty-five years and frequently lectures on the topic of rock art on the lower Susquehanna. He has also contributed a chapter about the river’s Safe Harbor petroglyphs to the book, The Rock-Art of Eastern North America, Capturing Images and Insight, published by University of Alabama Press in 2004.