You see them everywhere across the Southwest, symbols from an ancient and mysterious race — spirals, zigzag lines, strange stick figures, a hump-backed flute player. They appear on signs and billboards, on fashionable furniture and tee shirts.

These images were originally discovered etched in the rocks of canyons and mountains from deep in Mexico to the northern Rockies, from the Pacific to the yawning grasslands of the American prairie. They are most highly concentrated in the American Southwest — Arizona, New Mexico, Nevada, Colorado, Utah, Texas, and California — but have been found from coast to coast within the United States. There are thousands of these rock art sites throughout the Southwest; more than 7,000 have been cataloged in Utah alone.

Archaeologists tell us that they know little about these prehistoric images pecked onto rock surfaces known as “petroglyphs.” Deciphering and understanding their meaning has been elusive. Dating petroglyphs is uncertain at best, since carbon-dating techniques aren’t effective on the rock. Some images can be dated approximately according to their content — one panel of rock art in Canyon de Chelly depicts men on horseback and, therefore, must have been etched sometime after the arrival of the Spaniards and their horses.

Another method of dating petroglyphs is by determining the age of the desert varnish glaze on the rock surface. According to the experts at Petroglyph National Monument in Albuquerque, New Mexico, most petroglyphs date from AD 1300-1650, although some may be as much as 3,000 years old. Petroglyphs in Wyoming’s Legend Rock have been dated to at least 5,700 years of age.

Petroglyphs are associated primarily with the Puebloan cultures of both the present and the past, including an ancient people known as the Anasazi, credited with building the immense cliff-dwellings that pepper the Southwestern landscape.

Once thought to have mysteriously “disappeared,” around AD 1500, the Anasazi are now believed to be the ancestors of the present Pueblo Indians. Other authors of the petroglyphs include the Hohokam, another highly developed and possibly related civilization that inhabited southern Arizona, around Phoenix.

While the meaning of some petroglyph images is obvious — a hunter spearing a deer, for example — the meaning of many others remains elusive. John Kantner, author of the Sipapu website states, “There are many theories. Some scholars believe that they convey important information regarding village boundaries, farming field ownership, and other basic messages… Other scholars argue that they are symbols that were pecked or carved into rock faces during important rituals. And still, other archaeologists believe that they are just ‘doodles.’”

Many symbols have been determined to be clan or tribal symbols and are, therefore associated with territory. Others indicate the presence of game, shelter and water, but the more esoteric symbols such as zigzags, spirals, dots, concentric circles and others are less easy to define and have most often been relegated to the category of religious symbols. Archeoastronomers have also found that a number of the rock images are celestial in nature, indicating solstices and planetary movements, and certain sites have been found to be astronomical observatories similar in function to Stonehenge.