Petrified Forest | Puerco Pueblo Petroglyphs | Solar Calendars | Newspaper Rock | Puerco's Calendar

Puerco Solar Calendar

Pueblo Puerco's Solar Calendar

For several thousand years the early residents of the Southwestst have used rock surfaces as their drawing board. Recent research suggests that some petroglyph sites in Petrified Forest National Park are more than simple drawings - they are in fact solar calendars!

Watch an ancient solar calendar work from June 14th thru 28th at 8:30 a.m.
Spiral Petrogyph

Where is Pueblo Puerco and What Will You See?

Puerco Pueblo is located on the main park road almost midway between the north and south entrances. If you entered the park from Interstate 40, travel south on the park road for eleven miles. If you entered from Highway 180 travel north for fifteen miles.

A circular petroglyph etched on a boulder behind Puerco Pueblo marks the summer solstice. During the sun's morning trek, a shaft of light is projected onto the boulder and travels down the side to penetrate the center of the circle.

Circular Glyph

How Do Solar Observatories Work?

Solar Calendar Solar calendars are single petroglyphs, most commonly circles and spirals, which interact with sunlight and surrounding rocks to mark the passage of the seasons.

If you were to watch the sun rise and set over a long period of time, you would notice that the sun follows different paths throughout the year. In the summer it rises in the northeast and in the winter, it rises in the southeast. As the sun's position changes, shadows and sunlit images are projected onto the rock carvings. These projections mark the winter and summer solstice, the shortest and longest days of the year, as well as the equinoxes, the midpoints between the two solstices. Evidence also indicates that some petroglyphs interact 45 days before and after the winter solstice.


For hundreds of years these solar calendars have unerringly performed their function. Sadly, these petroglyphs may not survive long enough for scientists of this and future generations to unravel their meanings. Vandals and collectors continue to remove and deface petroglyph sites at an alarming pace. Your respect for these ancient artifacts will help ensure that they will be available for others to enjoy now and in the future.

The above information was adapted from the National Park Service.

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