I recently received a most interesting book entitled “Arte Rupestre en Jalisco” (Rock Art in Jalisco) by archaeologist Joseph Mountjoy, which was kindly given to me by the author himself after I asked him one too many questions about petroglyphs. Joe suggested I might find many of the answers I sought in the pages of this richly illustrated, 48-page book (all in Spanish) and I certainly did.
If anyone ought to know rock art, it’s Mountjoy, who registered his first pintura rupestre (rock painting) in 1964 and has analyzed some 20,000 glyphs since then. To fully appreciate his insights, you really ought to visit the fascinating museum he has set up in the Casa de Cultura in Mascota (140 kilometers west of Guadalajara), where you will find a whole room dedicated to petroglyphs, a project carried out in collaboration with National Geographic Magazine. Google Mascota Museum for more information.
Between now and your visit to Mascota, here are a few insights I gleaned while reading “Arte Rupestre en Jalisco.”
The great majority of rock-art designs, says Mountjoy, are related to ceremonies aimed at obtaining rain from the sun god for the benefit of those plants and animals that ancient peoples depended on for their sustenance. The ceremonies were related to that critical transition from dry to rainy season and the drawings were destined for a god rather than for fellow human beings.
As for the meaning of most rock art, Mountjoy says, “Approximately 98 percent of the petroglyphs (in western Jalisco) can be explained by 
only three intimately related factors: sun, water and fertility.”
As for the age of most Jalisco petroglyphs, the great majority were made during the Postclassic Period (900 to 1500 A.D.) although a few may go back to the time of Christ.
What are these interpretations based on? “In Jalisco, the main source of ethnographic information for interpreting rock art is the Huichol culture,” says Mountjoy. “They have preserved their culture, customs and beliefs quite well,” he points out, adding that the religious symbolism of the Huicholes was the subject of an extensive study carried out in the 19th century by ethnographer Carl Lumholtz.
Many of the rock-art designs we see could be interpreted as the physical manifestations of prayers offered up to the sun god to obtain some practical benefit. This, Mountjoy points out, is similar to the post-Conquest custom of filling the walls of some Catholic shrines with “milagritos,” testimonials giving thanks for favors received from on high.
Perusing the book’s many color photos of rock art, I learned that the symbol for the sun god is often a set of concentric circles, sometimes surrounded by rays, but it can also be as simple as an unadorned pit carved in the rock. The more elaborate designs can also have arms, legs and a tail, representing either the god in anthropomorphic form or a shaman who carries out rites supplicating the sun god.As for that other commonly seen symbol, the spiral, Mountjoy says it represents a coiled snake, which, he adds, represents water directly.
Since most petroglyphs are a prayer for water, it’s not surprising he’s found them to be most abundant in areas where rivers and pools 
typically dry up during the course of the dry season.
A fascinating section of the book is dedicated to a kind of rock engraving called the patole. This is the ancient equivalent of board games like backgammon or snakes and ladders. The “board” was engraved on a flat rock and for dice, the Aztecs used big beans painted with white dots and known as patoles.
The oldest patole petroglyphs go back to 300 B.C. and were found in places like Teotihuacán and Palenque. There was an elaborate kind of patole shaped like a rectangle with a cross in it with 52 spaces where your token could land (representing the Mesoamerican century) and also “abbreviated patoles” with only 12 spaces. Mountjoy found both styles in the Mascota area. “I should mention,” he says, “that for the Aztecs, playing patole also included drinking alcoholic beverages and gambling for high stakes.”
At the end of the book, we are reminded that most petroglyphs were considered sacred by their makers and that visiting sites with rock art should be considered like stepping into a temple or a church. Damaging petroglyphs or making fires near them (which can cause the rock to fragment) would be very offensive to native peoples.
“Arte Rupestre en Jalisco” is a thin, magazine-size (27 by 21.5 cm), 48-page paperback with 44 photos, almost all in color, beautifully printed by Acento Editores of Guadalajara. The price is 150 pesos and – for the moment – it is for sale exclusively at the Casa Cultural in Mascota.