Rattlesnake Canyon is a small, steep-sided canyon in southwestern Val Verde County; it begins west of Langtry and runs for several miles to its junction with the Rio Grande. The canyon is best known for its numerous pictographs, which date variously from prehistoric times up through the era of Spanish contact. Rattlesnake Canyon also contains other evidence of pre-Hispanic occupation, including piles of debris from the manufacture of stone tools, various used flake tools, burned rocks, circular stone alignments, and mortar holes. Most of the sites, like those in the rest of the Lower Pecos area, have been looted to some degree.
The canyon's smooth limestone walls and rockshelters provided the perfect canvas for Indian rock art. The natural aridity of this region of Texas, combined with the protection afforded by overhangs and rockshelters, allowed for the excellent preservation of some of the pictographs. Those pictographs, however, which were not protected beneath an overhang or in a rockshelter, but were instead painted directly on the canyon walls, have not been as well preserved. Some of these have been scoured by high water during the area's infrequent floods. Among the pictographs damaged by floodwaters was the famous historic-period Missionary Pictograph, which depicted a Spanish missionary pierced by a spear and a rendering of crosses and a horse. This site was first recorded by Lula and Olea Forrest Kirkland during their rock-art excursions in the 1930s, and was photographed a short time later by A. T. Jackson. The pictograph, unfortunately, was almost completely destroyed by the flood of 1954.
In the early 1990s the Rattlesnake Canyon land was owned by Texas Tech University, but at that time arrangements were being made to transfer ownership to the National Park Service. Rattlesnake Canyon, which is listed in the National Register of Historic Places, has been extensively surveyed, but as of the early 1990s, no sites in the canyon had been formally excavated. Early surveys in Rattlesnake Canyon concentrated on locating rock-art sites or sites with an obviously large prehistoric component. More recent surveys focussed not only on finding this type of site, but on locating smaller, less substantial sites as well. Because there had been little formal investigation of the sites in Rattlesnake Canyon, in the early 1990s there were almost no published materials about them, though some unpublished materials were housed at the Texas Archeological Research Laboratory at the J. J. Pickle Research Campus (formerly the Balcones Research Center) of the University of Texas at Austin. The primary published source for information about and illustrations of the rock art in Rattlesnake Canyon is The Rock Art of Texas Indians (1967), by Forrest Kirkland and W. W. Newcomb. Some of the rock art is also shown in Ancient Texans: Rock Art and Lifeways Along the Lower Pecos (1986), by Harry Shafer and Jim Zintgraff.
Forrest and Lula Kirkland are well known for the watercolors they produced of Texas rock art, especially that found in what is now Seminole Canyon State Historical Park, also in Val Verde County. In July 1936 they stopped by Rattlesnake Canyon and recorded the pictographs in three of the largest shelters. These pictographs are complex murals of painted and overpainted representations of animals and shamans and other anthropomorphic figures as well as abstract geometric designs. During their stop in Rattlesnake Canyon they also recorded the Missionary Pictograph. Besides the missionary figure and the horse, there are also positive handprints surrounding the figures. All are executed in the Red Monochrome style, a style used by later inhabitants of the Lower Pecos during the Late Prehistoric period, who are characterized by archeologist Solveig Turpin as newcomers to the area. This style first appears around A.D. 600 and persists in pictographs done until shortly after the arrival of the Spanish. The greater number of the paintings are executed in the Pecos River Style, which was popular from about 2500 B.C. to about 500 B.C. This is the oldest style found in the area and is the most distinct and common. Pecos River-Style paintings are generally polychrome renderings that include costumed shamans. Colors include red, yellow, orange, black, and white. Many of these figures wear horned headdresses and carry fringed pouches by their side. Frequently depictions of atlatls and fending sticks are associated with the shaman figures. Rattlesnake Canyon also has a large number of "airplane" figures.