The sandstone panel at V-Bar-V Historic Site is filled with a jumble of petroglyphs, etched into the rock up to 900 years ago by the Southern Sinagua who made their home in the Verde Valley's desert hills.
This time of year, the cliff face remains untouched by the sun until 12:45 p.m. when light cascades over its face, except for two parallel bands of shadow cast by rock outcrops.
The shadows seem insignificant until site volunteer Craig Swanson begins pointing to specific images — a zig zag line meant to be a planting calendar, two dancing figures and a representation of a leafy corn stalk. On the summer solstice, the shadows cast by the two rocks exactly touch the roots of the corn plant, land on the endpoint of the planting calendar and highlight the two dancing figures.
Those images, when uniquely linked by light and shadow, signaled this date to ancient peoples, a date with both agricultural and ceremonial significance. The solstice was the time to begin the final corn planting, the time when summer's monsoon season was near and the time to start preparations for the home dance ceremony, which ushered the katsina spirits back to their summer homes on the San Francisco Peaks, said Ken Zoll, executive director of the Verde Valley Archaeology Center.
Zoll calls the V-Bar-V solar panel the most complicated calendar in the entire northern Arizona area.
Across the region, ancient structures, pictographs and petroglyphs like those at the V-Bar-V site still mark the sun’s seasonal traverse across the sky.
They signal the equinoxes, the solstices, the start of their creators' religious ceremonies and important dates for planting and harvesting. Today, they intrigue local archaeologists and adventurers alike.
Designed to withstand the test of time, ancient solar calendars across the Southwest allow people today to experience parts of the world in a way that people experienced it hundreds of years ago, said Mike Campbell, owner of Canyonology Treks.
"It's no small feat," said Campbell, who recently traveled to a solstice marker at Petrified Forest National Park. “It’s not just a curiosity, it is in my eyes a scientific accomplishment. It takes the scientific method. It's observations, recording data and it takes foresight."
While they vary in their mechanism for sun tracking, northern Arizona’s solar calendars share similar purposes — marking the beginning of religious ceremonies and indicating the times to prepare, plant and harvest crops like beans, corn and agave, said several archaeologists who study the sites.
Many of the region's calendars also contain common images like concentric circles or spirals that symbolize “father sun," Zoll said.
It’s clear the images were created by a people that didn’t have the distractions of today, said David Purcell, supervisory archaeologist at the Museum of Northern Arizona.
“They were there with dark skies and they had a lot of time during the day to observe how the sunlight moves across their realm. They were fully living in their environment,” Purcell said. “This is a good expression of how close they are to this environment in this time period.”
WUPATKI SOLAR CALENDARS
Several individuals and groups around the region are searching for and studying these solar calendars. Zoll, for example, has documented close to 12 in the Verde Valley area over the past decade.
Purcell is leading another group of archaeologists with the Museum of Northern Arizona and the National Park Service. The group's three-year project aims to document thousands of petroglyphs on the rock faces of mesas deep in the backcountry of Wupatki National Monument. So far, the group has found at least one solar calendar where a spiral and eight discs arranged like a bunch of grapes have been pecked onto the rock face, Purcell said.
On the equinoxes, a dagger-shaped shadow cast by a natural outcropping slices through the center of the spiral. Then the day after the equinox, a U-shaped band of sunlight caused by the sun sinking behind a break in the mesa momentarily encompasses the bunch of discs.
The team’s guess is that the signal of the equinox would have told people to start counting to the day when crops could be planted, Purcell said.
The team has been using video and time-lapse photography to study that site and four other potential solar calendars at Wupatki since 2014. Next, Purcell said he’s hoping to set up a camera that would film the dagger-and-spiral panel for a year to verify that the shadows occur only on the equinox and not more regularly.
HUNTING FOR SOLSTICE MARKERS
Purcell and others said finding and verifying solar observation sites requires some luck, patient observation and long hours of study.
Bryan Bates, a professor emeritus at Coconino Community College, has spent more than 30 years scouting out different sites, watching how light and shadow interact on certain dates.
Serendipity has a great deal to do with it, Bates said. Then if a place looks interesting, confirming its use as a solar calendar requires finding evidence it was a place of cultural significance, which Bates said means going through archaeological records at places like the Museum of Northern Arizona and Cline Library.
Unequivocally verifying that a site is in fact a solar calendar isn’t a simple or defined process, Purcell said.
“There's a lot of arguing that goes on,” he said. “We're finding there is no set standard or seal of approval.”
When the ancient Pueblo people abandoned the area, they took with them the only absolute knowledge of the images’ meaning, said Jim Wilson, a volunteer at the V-Bar-V Heritage Site, said.
“It will never be fully discovered again,” he said.