Pictographs, Petroglyphs, “Rock Art,” What is the difference?

The National Archives is celebrating American Archives Month throughout October. Follow us on social media and share your archives stories using the hashtag #ArchivesMonth. Today’s post comes from Larry Shockley, an archives specialist at the National Archives at College Park, MD. 

The National Archives’ holdings offer many keys to understanding our past. With a simple search in our online catalog researchers can find information contained in millions of documents, maps, photographs, and more. One recent search led me to photographs of petroglyphs, pictographs, and “rock art” that reside within NARA’s holdings.

Some of the earliest photographs of a petroglyph that are in our online catalog were taken by the U.S. Army Corp of Engineers in 1956. Other photographs of pictographs, petroglyphs, and rock art made their way into NARA’s holdings courtesy of the DOCUMERICA project conducted by the Environmental Protection Agency (EPA) in the early 1970s. The works of photographers Charles O’Rear, David Hiser, and Patricia D. Duncan include these types of creations.

According to our friends with the National Park Service, the differences between petroglyphs, pictographs, and rock art are not always easily discernible.

The National Park Service defines pictographs as “images and designs made by painting on rocks or in caves.” The pictographs depicted in the photo below are at Indian Creek State Park in Utah. For this type of painting, plants and minerals were ground up and mixed with liquids and then applied with sticks, fingers, or hands. Due to the fragile nature of these creations, very few pictographs have survived the elements over time.

Petroglyphs are more commonly found, and these images were created by carving, engraving, or scratching the rock’s surface in order to reveal the lighter layers beneath. The depth and thickness of these images can vary depending upon whether they were scratched, pecked, abraded, incised, or carved onto a surface. The image below was taken at the mouth of the Nemaha River near Troy, Kansas. It is believed that this specific petroglyph was mentioned in journals from the Lewis and Clark Expedition.

Approximately 450 petroglyphs were discovered near Long Narrows and Celilo Falls, east of The Dalles, Oregon. The petroglyph pictured below is one of the 40 or so petroglyphs that were removed prior to the creation of The Dalles Dam and relocated to Columbia Hills State Park.  

“Rock art” is a generic label or tag often applied to both petroglyphs and pictographs, but the term is seldom used by the Park Service.

Although there are distinct differences between pictographs and petroglyphs, confusion between the two continues to occur. In addition to a lack of knowledge about the two processes, there are many examples where both petroglyphic and pictographic processes were employed to create “painted petrogyphs.” It is amazing how one simple search can take you down a road of discovery—take a look in the online catalog and see what you can find!