The Rock Art
The Project
Rock House Cave
Indian Cave
Learn More

Petit Jean Mountain is home to the most prolific concentration of Native American rock art in Arkansas. Hundreds of pictographs (painted images) have been identified at dozens of sites, along with a smaller number of petroglyphs (images carved or engraved onto natural rock surfaces). Motifs range from simple geometrics (circles, squares, diamonds, etc.) to naturalistic renderings of animals, plants, people, crafted items, and presumed celestial objects such as sunbursts. None of the art has been directly dated by radiocarbon or other measures (and indeed, many dating techniques don’t work on rock art), but comparison of art style and subject matter suggest that at least some images most likely date to late prehistoric times (ca. A.D. 900 – 1600). It is possible that some are much older. Rock art on Petit Jean Mountain is similar to examples found on many other prominences within the Arkansas River Valley that extend upstream past the Arkansas/Oklahoma state line.

Study of Petit Jean Mountain rock art began in 1914 when Dr. T. W. Hardison, a physician and local resident, began recording information about images he and his family discovered at sites near their home. With the establishment of Petit Jean State Park in 1923, stimulated in large part as a result of Hardison’s discoveries, these ancient motifs received greater public attention. Scholarly attention was intermittent throughout subsequent decades, but a systematic investigation begun by the Arkansas Archeological Survey during the late 1970s (that continues to the present) resulted in the listing of several sites on the National Register of Historic Places. P. Clay Sherrod (University of Arkansas at Little Rock) and Donald Higgins (another Petit Jean Mountain resident with keen interest in the region’s irreplaceable cultural resources) have undertaken additional investigations, resulting in the discovery of a large number of rock art sites that display many hundreds of images.

Work completed to date by these organizations and individuals has produced extensive documentation that makes projects like this one possible. Although a large number of images have faded or disappeared altogether as a result of both natural weathering and the acts of unthinking individuals wielding marking pens, cans of spray paint, or other implements, visible examples are preserved at a number of sites. Although digital techniques for photographic enhancement reveal a far larger number of images than can be observed with the naked eye, this presentation concentrates on visible imagery at Rockhouse Cave, where State Park visitors are invited to view the world as seen through the eyes of ancient Native American artists.

The 3D Petit Jean project uses state-of-the-art, laser scanning technology to create 3D models of the bluff shelters and the rock art that was created in them by Native Americans hundreds of years ago. This effort aims to precisely document the dozens of pictographs and petroglyphs and the complex environment they were created in as well provide a means to help visitors locate and understand them. Indian Cave is not accessible to visitors, but because of its restricted size and limited number of motifs, it provides an interesting contrast to the larger Rockhouse Cave – home to the largest concentration of rock art in Arkansas with over 100 motifs. Rockhouse Cave is also the only rock art site in Arkansas with public access. Thousands of visitors explore this bluff shelter each year in search of these interesting images, but most walk away without finding a single one. Many are quite small and difficult to see even to someone who has located them before; however, even the largest figures remain hidden to the great majority of visitors in the vastness and complexity of Rockhouse Cave.

In addition to assisting visitors find and learn more about these interesting images, another goal of this project is to create a 3D scaled model of each shelter and their surrounding environments to educate the public about the location and history of rock art in the park. The results have been published on this website and are also available as part of two interactive kiosks that have been installed in Mather Lodge at Petit Jean State Park.


The Technology

Funded by the Arkansas Natural and Cultural Resources Council, researchers from the Center for Advanced Spatial Technologies (CAST) at the University of Arkansas documented both shelters using the Leica C10 long range scanner. The Leica C10 is a time-of-flight scanner that captures 3-dimensional data with color texture at a rate of up to 50,000 points/second. When surveying with the C10, multiple scans are acquired across a location and all scans are stitched together using specialized software to create a complete 3D, scaled representation of a site. The resulting dataset is commonly referred to as a point cloud in which each point represents a 3D position measured by the scanner (X,Y,Z) with color information (R,G,B). It is fairly typical for a final merged dataset to contain hundreds of millions or even billions of points depending on the size and complexity of the area surveyed.

While numerous products can be derived from a 3D point cloud, the point cloud on its own can be a very compelling visualization tool. For this project, it was decided that the 3D point cloud would be the ideal format for visualizing each of the bluff shelter locations. Project researchers at CAST then had to determine how to display a 3D point cloud directly in browser. While 3D content on the web has typically required the end user to download a third party plugin, recent advances in WebGL are now allowing developers to directly embed 3D graphics in websites using standard javascript libraries (that do not require a browser plugin). This website uses Three.js to support the viewing and manipulation of the 3D point cloud site data for each of the bluff shelters.


The Final Product

Project developers created a custom application using Three.js that allows web users to virtually explore both Indian Cave and Rockhouse Cave. Users are encouraged to view and discover the Native American rock art present at each location. Once found, the user can select each individual motif to retrieve additional content. When a motif is selected, the user has the ability to view a video, featuring renowned rock art expert and archaeologist, Dr. George Sabo providing an interpretation of the rock art, and to also view an enhanced set of images that tease the rock art out of its surrounding context. Researchers used the DStretch plugin (http://www.dstretch.com/) to accentuate the rock art in the photographs. Additional information about the art at each shelter is located in the information panel on the left side of the screen.