|Although the ancient people of the Southwest didn't have a written language, they had effective ways to communicate. Cultures worldwide have used rock art to transmit ideas and beliefs. There are two types of rock art, petroglyphs and pictographs. Petroglyphs are images carved or pecked into a rock surface. In Chaco Canyon, petroglyphs are carved into the sandstone cliffs that form the canyon walls. Many are located on boulders. Pictographs, images painted on a rock surface, are less common in Chaco Canyon because the paint erodes over time.
At Chaco, and throughout the American Southwest, rock images were probably an important form of visual communication. Some are images of clan symbols; others are records of important events during migrations. Still others are memory aids for recalling stories, songs, and ceremonies. Today, descendants often recognize Chaco's petroglyphs and pictographs as records of the migrations of clans, and as other affirmations of meaningful and ongoing associations with sites.
Many Chacoan petroglyphs are geometric designs such as spirals, mazes, and hatching. There are some depictions of stick figures or stylized humans, flute players, hands, sandals, mountain sheep, birds, and insects. One of the most famous petroglyphs in Chaco Canyon is the Sun Dagger. It consists of two spirals that mark the annual solstices and equinoxes. More recent historic-era pictographs and petroglyphs depict scenes of dancers, men on horseback, and Navajo deities.
Since the 1970s, there have been several surveys documenting petroglyphs and pictographs at Chaco Culture National Historical Park. Several of these can be seen in the slide show (see link to left).