Drought reveals dozens of ancient petroglyphs submerged under a Mexican lake.

Valle de Bravo, Mexico. Over the past few days our team was able to document dozens of ancient petroglyphs that emerged from the waters of Lake Avandaro in Valle de Bravo, Mexico, for the first time in over a decade. The petroglyphs, which are located very near the shore, may date to the Teotihuacan period, or nearly 2,000 years old. The site was submerged when a dam was created in 1947 leading to the formation of Lake Avandaro, and is only rarely visible when the rocks are uncovered during exceptional drought conditions, as it has been the case for the past few months. 

The main group of petroglyphs located inside a small rock shelter or cave. All the surfaces of the cave, including the floor and ceiling are decorated with geometric and other abstract symbols.

Among the numerous petroglyphs are several astronomical markers or pecked crosses, typical of the Teotihuacan culture that dominated central Mexico in the first centuries of our era, as well as solar symbols and other abstract and geometric carvings. A small cave alone contains dozens of petroglyphs including circles, spirals as well as lines and other abstract shapes that may form part of a map. Another rock nearby bears a diagram of what appears to be a temple or shrine approached by a monumental double stairway. There are also several architectural models of what appear to be pyramids with steps, unfortunately now badly eroded. More submerged petroglyphs and rock carvings are said to lie submerged in the waters of Lake Avandaro. Unfortunately the constant water erosion from the lake has now erased most of the carvings and it is doubtful they will survive for much longer unless efforts are taken for their preservation and documentation.

A typical Teotihuacan pecked cross, likely used as an astronomical marker or for calendar calculations.

An important prehispanic settlement was located in Valle de Bravo near La Peña, containing several small pyramids and monumental sculptures like the pair of giant serpent stone heads now housed in the small archaeological museum of Valle de Bravo, showing a strong Teotihuacan influence. 

A detailed view of the main group of petroglyphs on the bottom wall of the rock shelter near the lake shore.

One of the walls of the rock shelter, entirely covered in petroglyphs. These include several circles connected by lines that may represent constellations or a map of the area.

Another view of the same rock shelter taken from the entrance. Some faint petroglyphs are also visible on the floor and ceiling.

More carvings and petroglyphs near the entrance.

A badly eroded architectural model carved from a single colossal stone, depicting what appear to be a group of pyramids surrounding a central plaza. The very faint outlines of steps can be made out on the rock surface.

Another view of the same stone showing more stepped carvings.

The location of the main petroglyphs site, near the shore of Lake Avandaro. These huge rocks are usually submerged under the waters of the lake.

More carved boulders near the shore. The group of stones barely emerging from the water in the distance form part of another architectural model depicting a pyramid and Mesoamerican ballcourt.

Huge boulders apparently carved and piled together near the shore. Any petroglyphs that may have once been present on their surface have now disappeared.

A huge carved stone with an artificially flattened top. The outlines of several faint stairways and stepped symbols are visible to the right of the stone.

Another stone with small steps carved into it. It may have symbolized a sacred mountain or peak.

A solar symbol carved on a large boulder. The first rays of the sun illuminate this stone on the morning of the Winter Solstice.

Deeply carved grooves in one huge boulder.

Another badly eroded architectural model of a stepped structure (left), possibly a pyramid or temple, with a broad central stairway. It is still possible to make out the faint outlines of steps.

A typical Teotihuacan pecked cross, likely used as an astronomical marker or for calendar calculations. One of the arms of the cross points in the direction of La Pena, a large rocky outcrop on the opposite shore of the lake where a ceremonial center and numerous caves were located.

One of the most intriguing carvings is this representation of what appears to be an architectural plan. Two square structures, possibly pyramids or temples, are approached by monumental stairways. The uppermost one appears to be connected to a set of three chambers in a cruciform arrangement, connected by a corridor. 

Another badly eroded petroglyph - One of several dozens on boulders near the shore, now threatened by the waters of the lake.