A mysterious series of petroglyphs made by the Pueblo people of southwestern United States have been deciphered. These beautiful examples of rock art have been proven to record the passage of the season and astronomical observations. They also provide evidence for their culture and sophisticated traditions over 800 years.

A team of archaeologists, led by Radek Palonka of Jagiellonian of the University in Kraków, Poland, was investigating panels of petroglyphs in the Mesa Verde region, Colorado. Since 2011, they have been working, along with local volunteers, on the Castle Pueblo site that is part of the Canyons of the Ancients National Monument. They are only one of a handful of European archaeologists who have worked in this area.

The excavation site where the rock art of the Pueblo people was found. ( Jagiellonian University )

Ancient Pueblo People

The petroglyphs or rock art were made some 800 years ago. They were made by chipping the surface of rock away and applying pigments, by the ancient Puebloan people who are the ancestors of the modern Hopi tribe. They evolved from nomadic hunter-gathers and became settled farmers. They developed a sophisticated irrigation system and built distinctive buildings made of adobe. According to IBT, “the ancient Puebloans’ way of life declined in the 1300s, probably due to drought and intertribal warfare, which forced them to migrate to the south.”

Ethnographic researchers in the 19th century believed that the rock art was probably used as solar calendars. Experts believe that based on analogies with other cultures, such art was used to record astronomical observations. The archaeologists wanted to establish the meaning of the Puebloan rock art, and if it was used to demine astronomical events such as equinoxes.

Polish archaeologist analyzing some of the Pueblo people’s rock art found at the Mesa Verde site in Colorado. ( Jagiellonian University )

At one location, the Polish team studied a panel of petroglyphs carved on a wall of a rock shelter. “The panel consists of three different spirals and several smaller elements, such as rectangular motifs and numerous hollows,” according to Archaeology News Network.

3D Imaging Leads to Breakthrough

The archaeologists used breakthrough technologies in their study of 13 th-century art, including laser scanning and photogrammetry. They took many images of the petroglyphs, and they recreated them in three dimensions. Live Science quotes Palonka, as saying the purpose of this was “so we were able to see more stuff on the rocks than it is possible to see only with the naked eye.”

Close up of the spiral patterns that appear prominently in the rock carvings and are thought to be a symbol among ancestral Pueblo people for the sky or the sun. ( Jagiellonian University )

What they found was amazing and demonstrates how sophisticated the ancestral Puebloan people were. The rock art was intentionally made to display complex interactions between light and shadow. These are most apparent during winter and summer solstices and also around the equinoxes in the fall and spring.

Astronomical Observations

Palonka told Live Science that on the winter solstice (December 22), “patterns of sunlight and shadow can be seen to move through the spirals, grooves and other parts of the petroglyphs.” This also occurs during the fall and spring equinoxes, when there are equal hours in the nights and days. Yet it does not happen at other times of the year.

Patterns of sunlight and shadow move across the rock carvings only at certain times of the day, and only for a few days around the solstices and equinoxes, showing the sophistication of the Pueblo people. ( Jagiellonian University )

There are similar petroglyphs at another Puebloan site, in nearby Sandy Canyon, which are similarly illuminated. Unlike these, the petroglyphs studied by the team were “lit by sunlight only in the late mornings and early afternoons around the summer solstice,” according to Palonka, reports Archaeology News Networks .

The calendar would have helped the Pueblo people to know when to plant their seed, which is very important for agricultural people. The rock art also shows scenes of traditional Puebloan culture and their ceremonies, which seem to have been tied to the solar calendar. This is very similar to those practiced by modern-day Hopi people and would suggest a great deal of cultural continuity among Native Americans in the region.

Polish archaeologists exploring the site where the rock art of the Pueblo people was found at the Mesa Verde site in Colorado. ( Jagiellonian University )

Hopi Community Collaboration

The team is collaborating with local Hopi community leaders, who are helping them to better understand the carvings. Live Science quotes Palonka “this collaboration with native people, in this case, Hopi people from Arizona, is really important.” The Hopi have explained that the symbol of a spiral represented the sky, but not in every case.

During their investigations, the team has also found a number of undocumented carvings. More surveys of rock art in the Canyons of the Ancients National Monument, in Colorado, are planned in the future, especially with regard to their role in observing and recording astronomical phenomena.

Top image: Main: Cliff Palace in Mesa Verde, ruins of an Anasazi Pueblo people, near where the rock art was found. Source: Dietmar / Adobe stock. Inset: The spiral patterns that appear prominently in the rock carvings are thought to be a symbol among ancestral Pueblo people for the sky or the sun. Source: Jagiellonian University

By Ed Whelan