Museum of Northern Arizona exterior

Science Saturday: The Natural History of Rock Art

By David E. Purcell

Native Americans made rock images for many reasons. Petroglyphs (pecked or cut into the rock surface) and pictographs (painted images) recall migrations, are created as part of religious ceremonies, document the activities of families or clans, or mark the passage of the seasons. Among the images visible at rock art sites are depictions of animals and sometimes plants, a tradition that began more than 40,000 years ago in the Paleolithic era in Europe and Asia. The famous paintings and inscriptions at sites like Lascaux in France and Altamira in Spain provide detailed records of animals in the Ice Age environment of the painters. Even though these images, like those in the Southwest, held other meanings for those who created them and those who viewed them, they also provide scientists with important information about the climate and environment of the time and place the art was made.

Wupatki National Monument northeast of Flagstaff contains a dense concentration of rock art made by ancestors of the Puebloan people between 900 and 800 years ago. The Museum of Northern Arizona and the National Park Service partnered in a study of over 4000 petroglyphs at four sites in Wupatki between 2014 and 2017. With bare rock and sparse grasses dominating the view, the current environment of the area seems desolate and forbidding to life. The most barren areas are on the talus slopes and around the cliff faces where the petroglyphs are most numerous. The only plants growing in this zone are native desert tobacco (Nicotiana trigonophylla) and many-headed barrel cactus (Echinocactus polycephalus), which is more common in southern California and Nevada and western Arizona between 1,000 and 2,500 feet elevation. Images of these two plants have not been identified among the petroglyphs.

The rock art does show other plants and animals in the modern environment of the sites. Pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus), or both, are commonly depicted, with over a hundred individual petroglyphs identified as antlered quadrupeds. Other animals are easier to recognize: bighorn sheep (Ovis canadensis), snakes, lizards, even a bat. Although one petroglyph is an accurate portrayal of a rattlesnake, with triangular head and rattles, none have been observed in the area. Yet, roadrunners (Geococcyx californianus), a top predator of rattlesnakes, have been reported in the vicinity, and at least one petroglyph appears to be an image of this distinctive long-tailed bird. Stylized petroglyph images of maize (corn, Zea mays) plants are probably clan symbols, and record visits to the site, but corn was also an important domestic crop that would have been grown on the Little Colorado River floodplain.

Among the creatures now living near the petroglyphs, there are many lizards, such as desert spiny (Sceloporus magister), collared (Crotaphytus collaris), and longnose leopard lizards (Gambelia wislizenii). Birds are also common, both on the wing today and depicted in rock art on the cliff faces. American kestrels (Falco sparverius), ravens (Corvus corax), crows (Corvus brachyrhynchos), bald eagles (Haliaeetus leucocephalus), and canyon wrens (Catherpes mexicanus) frequent the cliffs and mesas of Wupatki. Petroglyphs immortalize a variety of birds including images of tall wading birds that are probably American bittern (Botaurus lentiginosus) or great blue heron (Ardea herodias), as well as eagles.

Without the distractions of smart phones and other attention-claiming devices, the ancient residents of the Southwest had plenty of time to observe the natural world around them, and to preserve their observations as images on stone. Through their eyes we can picture Antelope Prairie in what is now Wupatki teeming with herds of pronghorn and deer, and the rich environment of the floodplain before it was overrun with the invasive tamarisk tree. As the climate continues to change in response to human activity and natural cycles, the rock images of Wupatki and other locations provide us with an important index of those changes. This is yet another good reason to view and appreciate ancient rock art, but not deface it with names or dates. To learn more about Southwestern rock images visit Wupatki National Monument or check out the most recent issue of MNA’s magazine Plateau, “Wupatki National Monument: New Perspectives On Petroglyphs Of The Crack-In-Rock Community.”

David Purcell is the Supervisory Archaeologist for the Museum of Northern Arizona.

Total Word Count: 689 – including species names