Rock Art in Mexico

Article | Updated 8 years ago

Report on Ian MacLeod’s rock art conservation program and site visits in Mexico.

During a recent period of annual leave Dr MacLeod gave a customised 4 day rock art conservation and microclimate management course at the Coordinación Nacional de Conservación (CNCPC) centre in Mexico City.

There are six rock art conservators directly employed by the centre, which coordinates the work of more than 272 conservators and technicians across the country. More than 50 conservators attended the program. With more than 700,000 rock art sites to manage the need for having regional teams is strongly supported by the CNCPC.

A public lecture on the way in which shipwreck corrosion products can inform the public on the past fate of vessels was a sell out and it was noted that Mexico has ratified the UNESCO convention on the management of shipwrecks. Australia lags behind in this recognition program.

Fieldwork involved a two-hour flight to La Paz in southern Baja California and a four-hour drive to Loreto and inspection of a rock art site. This site had been almost completely buried by riverine sediments being dropped in front of the artwork at a bend in the riverbed as heavy rains bring down large amounts of material from the mountains. Measurements of biological activity were made on the exposed sections and when the site was revisited four days later, torrential rain had caused the underlying rocks to become a source of freshly alkalinised water that washed away all acidic metabolites from bacteria and reset the deterioration clock back to zero. 

A few hundred more kilometres north and a lot of ascending brought us to the high plateau of the Sierra of San Francisco and the cave of the mouse (Cueva del Ratón) where giant paintings of deer and black panthers abound.

The area is a Unesco World Heritage site and ours were the first direct measurements of surface pH of the paintings and the background rocks.

Along with nitrate, sulphate and chloride readings it was possible to gauge what impact the biological deterioration was having on the survival of the rock paintings. After a long return to our accommodation in the centre of San Ignacio the incoming cyclonic depression necessitated a journey to the next site. This involved two hours of rough country travelling followed by a 4 km walk carrying instruments and an 850-metre climb to a giant shelter near the top of the range. Here, giant size rock paintings, more than four times life size, are found 15-20 metres above the cave floor. The Cuest Palmarito site is certainly one of the most spectacular sites I have ever seen. As measurements were concluded a massive thunderstorm broke and the front of the giant cave was covered with a bridal veil waterfall.

Our walk out meant we waded through creeks that had hours before been our ascending route on dry ground. One of the vehicles kept getting bogged so this involved a lot of use of towropes and muddy encounters with other vehicles. Somewhat exhausted after an 18-hour day, we eventually returned to the hotel to no running water, no power and no food.  All in all, a brilliant experience.

During excursions into Mexico City the giant metropolitical cathedral of the Ascended Mary gave glimpses of the glories of 17^th century Spanish church and organ building and a roof top inspection of the ancient cathedral gave access to the northern belfry and the sounds of a 14 tonne bell.