Mexico Life
Petroglyphs at the Rock Art Sanctuary in Jalisco. Petroglyphs at the Rock Art Sanctuary in Jalisco.

Petroglyph calendars and rock art in Jalisco

Rock-Art Sanctuary discovered in 2006 has more than 850 petroglyphs

More than 850 petroglyphs have been discovered along the shores of La Presa de la Luz, a small, dammed up lake located some 100 kilometers east of the city of Guadalajara.

Archaeologists Rodrigo Esparza and Francisco Rodríguez have reason to believe that the site may have been used as an astronomical observatory over 1,000 years ago.

The two archaeologists have described their findings in scholarly articles and recently in an elegant 154-page hardcover book in Spanish entitled El Santuario Rupestre de los Altos de Jalisco (The Rock-Art Sanctuary of the Jalisco Highlands).

With the help of nearly 200 color photos and diagrams, they reveal — in laymen’s terms — some of the secrets of this extraordinary site, while simultaneously raising new questions about it.

The discovery of the petroglyphs took place in 2006, the book tells us, when Don Lupe, foreman of a ranch next to the dam, was clearing an area of the shore to make a corral. The tractor scraped away a rather thin layer of topsoil covering the flat, underlying rock and Don Lupe noticed some curious marks on the newly exposed surface.

He got a shovel and carefully removed the dirt, revealing not just one ancient engraving, but a whole collection of them, covering an area of some 25 square meters. This spot is now known as “El Planchón Principal,” or The Big Slab, and contains some 40 individual designs.

Dominating the rock art on The Big Slab are two pecked crosses, each set in the center of a pair of concentric circles. As their name indicates, all the lines in a pecked cross consist of dots (also called cups) drilled or pecked into the rock. These crosses have been found in other parts of western and central Mexico and are principally related to the Teotihuacan culture.

The arms of the crosses are oriented toward the four cardinal points and some researchers think they are solar calendars. In the opinion of Esparza and Rodríguez, the engravings on The Big Slab represent the movement of the sun and other stars over the period of a year and mark seasonal changes, such as the solstices and equinoxes. However, they stress that scientific studies still need to be carried out to corroborate this theory.

The same holds for dates. The archaeologists estimate that the petroglyphs may date back to the year 500 but, they say, “We need to carry out a far more detailed study of the engraving techniques, which should tell us whether all the designs have the same age or whether they were made at different periods by different societies.”

A total of 16 pecked crosses have been found at the Rock Art Sanctuary. “Figuring out what the pecked crosses mean has been a headache for researchers,” say the archaeologists. Pecked crosses have 260 points which coincide exactly with the number of days in the Mesoamerican calendar, so perhaps they were used for keeping track of time.

However, the cross in the center of the circles is usually oriented toward the four directions, so perhaps they constitute a kind of pre-Hispanic compass, divided into 260 degrees, just as our modern compasses have 360 degrees, roughly the number of days in our own calendar.

The designs around (and sometimes within) the pecked crosses might indicate when to carry out practical activities such as hunting, planting and harvesting or the beginning of the rainy and dry seasons. It is even possible that they are records of astronomical events, the alignment of the planets or even the explosion of a supernova.

The spiral is the most common design found in rock art, from Alaska to Patagonia, and around 150 have been registered at Presa de la Luz. Much speculation is made on what the spirals represent: lakes, springs, mountains, wind, gods and the very circle of birth and death have been suggested.

I should note that a simpler explanation is given by archaeologist Joseph Mountjoy, author of the book Arte Rupestre en Jalisco (Rock Art in Jalisco), who suggests that each spiral is basically a prayer requesting rain. A similar meaning might apply to the many pocitos or little pits carved into the rock all around the area.

Mountjoy suggests they may be an uncomplicated way to depict the sun god, making them also a kind of prayer, although some of the larger pocitos have been described as “fixed mortars” for crushing plants and grain.

It is surprising to note that among the 857 designs at Presa de la Luz, only two represent human anatomy. One is a full-length figure of a woman and the other is a foot. A great many of the designs might be described as elaborate and maze-like, with several elements connected by a single, often meandering line.

Esparza and Rodríguez are now working with a third archaeologist, Teruaki Yoshida of Tokai University in Japan. Their most recent project is a dig to investigate the ruins of an ancient ceremonial center located in a field of agaves near Presa de la Luz.

“Dating petroglyphs is very difficult,” says Esparza, “but nearby we have found the remains of several structures which ought to tell us a great deal about who did the art work and when they did it.”

In May, four test pits were dug resulting in the uncovering of a rectangular altar located in the middle of a wide, sunken patio. “The first thing we noticed was that this altar is closely related to those found in the Bajío culture, which flourished in this area from 600 to 900 A.D., so it appears to be part of this tradition.

This has encouraged us to do another dig, hopefully this coming January. So we now have high hopes of learning much more about the people who carved the petroglyphs at this rock-art sanctuary.”

Unfortunately, the fact that these horizontal petroglyphs can easily be stepped on and that the rock they are carved in is rather soft means that the place is not open to the public and may never be.

This makes Esparza and Rodríguez’ book all the more valuable to people interested in fathoming the secrets of the ancient inhabitants of Mexico. It can be purchased for 400 pesos by contacting

The writer has lived near Guadalajara, Jalisco, for 31 years, and is the author of “A Guide to West Mexico’s Guachimontones and Surrounding Area” and co-author of “Outdoors in Western Mexico.” More of his writing can be found on his website.

  • petroglyphs-1
  • petroglyphs-9
  • petroglyphs-3
  • petroglyphs-4
  • petroglyphs-5
  • petroglyphs-7
  • petroglyphs-10
  • petroglyphs-11
  • petroglyphs-13
  • petroglyphs-12
  • petroglyphs-8
  • petroglyphs-2

Reader forum