The Fantastic Balls in el Cerro Piedras Bola
By: Édgar Anaya Rodríguez
One can see the curved shapes of the half-buried rocks, of the rocks that are
completely out in the open and those of which one can only see a small part from among the
shadows of the tree branches.
The wives of the giants who made their homes in this mountain a long time ago
were large, heavy -very heavy-, slow moving and they did not say much. How big are
these rocks? Nine meters? twenty? How, when and where did they live? Almost none of the
remains of these enormous beings survived the course of time; only that which would appear
to be the most trivial: their toys, or their stone balls, as round as any
other ball, and enormous, just as they were.
That was how some of the inhabitants of the place imagined the origins of these
amazing rocks. Only some of them believe this, because others affirm that the rocks were
made by extraterrestrials on one of their many journeys to the area. There are also those
who believe that they were created by the pre Hispanic Indians.
THE MASTER SCULPTOR
If spheres are enigmatic in and of themselves, how much more so is this
collection of rocks, which, when standing alongside them, make a human being look like an
ant playing among marbles.
The questions, who, when, how and why these spherical rocks were created strike
one the minute you set your eyes on them. Where they were made is the simplest question to
answer: they are located in cerro Piedras Bola, a part of the Sierra de Ameca, an
important volcanically active area about two hours walk from the nearest town,
Ahualulco de Mercado.
Among these rocks, the first one to become famous was the one at the entrance to
one of the mines in the area, called Piedra Bola. Over time, Piedras Bola in
the plural- was the name given to the tree-covered hill where dozens of these spherical
rocks in varying sizes are located (this is the only place where these rocks can be
found). They have an average diameter of between one and two meters, although some of them
have a diameter of up to three meters.
American geologists determined their origins and age after they had visited cerro
Piedras Bola in 1968. Their analysis, based on research done on other naturally spherical
rocks those in New Mexico, USA, have similar origins but the biggest are only some
60 cm in diameter- concluded that the rocks were formed about 40 million years ago during
the Tertiary period, through the chance crystallization of volcanic ash (attributed by
some to have come from the Tequila volcano, only about 30 km away). This still candescent
material, with temperatures estimated to reach between 500º and 800 º C, spewed from the
volcano and flooded canyons. When it settled and cooled, concentric layers of molten rock
underwent a crystallization process around glass particles contained in the molten
material. These processes stopped due to cooling during different eras, depending on their
location in the ash deposit. The result was these balls, formed in layers of
different sizes, similar to an onion.
Over time, wind and climactic conditions have uncovered many of the spherical
rocks buried in un-crystallized ash under the surface of the earth.
AND NOT SO WELL LIKED.
There are many examples of spherical rocks used as adornments in the San Fernando
Plaza, near the Hidalgo metro station, in Motolinía Street, and in the Centro Médico
Siglo XXI in Mexico City and in other towns and cities. Long before this, these rocks were
perhaps also sculpted into spheres for decorative purposes: Olmec spheres carved out of
basalt a type of rock that has never been found in naturally spherical form- were
found in the south of the state of Veracruz; these amazing shapes have also been found in
such places as Honduras, Belize, and Costa Rica.
The 1.5 cm-diameter spherical rocks, found in El Palmar in the southeast of Costa
Rica are not perfect spheres. Some 70 of these rocks were found by archeologists in the
1930s when a fruit company decided to sow orchards of fruit trees on these old flooded
plains. Some of them are about two meters tall higher than the average adult- and
weigh up to 16 tons. However, the archeologists have concluded that these balls
were carved by pre Hispanic Indians. Many of them are still half-buried in El Palmar, but
others have been taken by crane to San José, the capital of Costa Rica and used to
decorate peoples gardens.
Neither did the balls found in Jalisco, Mexico, escape the
devastation caused by man when he comes across natural treasures. In spite of the
fact that they are not very well known, even in the region, several of them have been
defaced by visitors, and there are only remains of many others that were blown up with
dynamite when the rumor spread that they contained a gold center. The locals speak of a
mother stone that was rolled down a hill and destroyed. This rock weighed 30
On the part of the hill called Las Torrecillas, soil erosion over the years left
the balls perched on top of columns of earth, forming strange, formidable
sculptures that daily are subject to being knocked down by ignorant idiots. Instead
of providing security for these historical formations and educating the public about them,
there is only garbage and ignorance.
The spherical rocks at Piedras Bola -a masterpiece of nature- are yet another
example of the marvels generally unknown in Mexico.
TO THE ROCKS
México desconocido No. 23 (1978)
contains a description of what was in those days
called the giants ball. They look like they are ready to be used
as bowling balls
the surface of the rock is rough and eroded by the weather and
possibly by movements of the earth.
The same article mentions that there is a unique adornment on the church in the
town of Ahualulco de Mercado, the nearest town to cerro Piedras Bola. Today, that
adornment sits on a pedestal in the gardens of the towns main park. It is a
spherical rock about 40 cm in diameter that served as a valve in the sluice gates of a
nearby dam. Some say that the rock is natural in origin, but that it was polished by
someone; others say that it was sculpted. What is certain is that today it is a monument
in honor of the rocks on the nearby hill and has almost become the symbol of the town of
Another spherical rock almost one meter high lies in a space in front of a
government office building, giving the welcome, as it were, on behalf of all the other
similar rocks that have made Ahualulco famous.
Other carved rocks catch ones attention in the towns main park where
you can also enjoy a regional corn drink called tejuino;
these were made to flatten and extract the juice of the tequila-producing agave plant.
Now retired from service, these round millstones are used solely for decorative purposes.
Trade in Ahualulco takes place in the tranquility of the plaza, between the palm
trees surrounding the old buildings and the church with its Gothic-like tower. The
atmosphere created by the mines in the nearby hills is no longer there. The mines that
reached their peak about one hundred years ago were mainly lead and tin mines, and today
they have been closed.
IF YOU'RE GOING TO
CERRO PIEDRAS BOLA...
Leave Guadalajara on
Highway No. 15 at Km 28 and take the turn-off for Federal Highway No. 70 to El Refugio.
From there, take State Highway No. 17 to Ahualulco de Mercado. From there, take the
special mountain path (you will need a guide) and you will find the cerro Piedras Bola
some 10 km from the town.
México desconocido # 305 / July 2002