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Petroglyphs at boca de Potrerillos, Nuevo León México. Source: theneonjaguar /Adobe Stock

Boca de Potrerillos: Mysterious Rock Art in a Mexican Desert

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More than 4000 pieces of rock art, the majority being petroglyphs, have been recorded at the site of  Boca de Potrerillos in Nuevo León, Mexico. This is considered one of the most important rock art sites in the country. Boca de Potrerillos first drew the attention of archaeologists during the 1960s, and the site was studied in the decades that followed, but there are still big mysteries surrounding the rock art of Boca de Potrerillos.

One of these mysteries is the purpose of these objects. Another is the identity of the people (or groups of people) who created the works of art . To date, these questions have not been answered satisfactorily.

Researchers are still working to find out who created this rock art and the reasons why. (Biologo Jorge Ayala/CC BY SA 4.0)

Researchers are still working to find out who created this rock art and the reasons why. (Biologo Jorge Ayala/ CC BY SA 4.0 )

Life at the Mouth of a Canyon

Boca de Potrerillos is located not far from Mina, a town in Nuevo León, Mexico. This archaeological site derives its name, which translates into English as the ‘Mouth of the Potrerillos’ from the fact that it is the entrance to the Potrerillos Canyon. The site lies between two mountains, El Antrisco and La Zorra, thus forming the canyon’s entrance. The name of the site was given during the 19th century, around the time when the Viceroyalty of New Spain ended. At that time, a wine-growing ranch called Boca de Potrerillos was built in that area.

Today, Boca de Potrerillos is located within a desert landscape, and covers an area of 6 km 2 (600 ha). Palaeoenvironmental studies of the site, however, suggest that there were periods in the past when the local climate was less severe than it is today. This means that it was possible for humans to live in Boca de Potrerillos during those times .

Although human beings could live in Boca de Potrerillos when the area was experiencing milder climatic conditions, the area’s inhabitants were hunter-gatherers, and were therefore most likely living a nomadic way of life. This is evident, for instance, in the absence of traces of permanent settlements in the archaeological record.

Today, Boca de Potrerillos is located within a desert landscape. (Ebarella_R/CC BY 2.0)

Today, Boca de Potrerillos is located within a desert landscape. (Ebarella_R/ CC BY 2.0 )

The Spanish colonists, who wrote extensively about the native peoples of Mexico, make no mention about any large civilization in that part of the country. This does not mean, however, that no traces of human habitation have been found at Boca de Potrerillos. For instance, objects such as spear points, pots, and amulets have been unearthed. Moreover, fogones, which are ovens made from piles of rock, have also been found.

Samples of coal from these fogones have been radiocarbon dated, which suggest that the site may have been occupied by human beings as early as 8900 BC. The evidence also suggests that humans were living in the area as late as the 18th century. In addition, the archaeological remains suggest that during prehistoric times, the site could support a large population, at least on a seasonal basis.

Finding the Rock Art of Boca de Potrerillos

The most impressive archaeological discovery made at Boca de Potrerillos, however, is its rock art. This first came to the attention of archaeologists during the 1960s. The site was first reported in 1963 by María Antonieta Espejo, who was working for Mexico’s Instituto Nacional de Antropología e Historia or INAH (National Institute of Anthropology and History).

Subsequently, the site was studied by a number of rock art experts during the 1980s. In 1991, a joint ‘Boca de Potrerillos Project’ was initiated by INAH and the University of Texas at Austin. In addition to archaeological investigations, the site was also turned into a tourist attraction, and was officially opened to the public in November 1995.

Most of the rock art at Boca de Potrerillos are petroglyphs, though there are some paintings as well. Petroglyphs are rock engravings formed by the removal of part of the rock’s surface. As a matter of fact, the word ‘petroglyph’ is formed by two Greek words, ‘petros’ and ‘glyphe’, which mean ‘stone’ and ‘carving’ respectively.

Most of the rock art at Boca de Potrerillos are petroglyphs. (Biologo Jorge Ayala/CC BY SA 4.0)

Most of the rock art at Boca de Potrerillos are petroglyphs. (Biologo Jorge Ayala/ CC BY SA 4.0 )

In spite of its name, carving was not the only means by which a petroglyph could be made. The surface of rocks could also be removed through incision, pecking, and abrasion. Petroglyphs have been found all over the world, with North America having more petroglyph sites than any other continent. Incidentally, as of 2005, 2839 rock art sites were identified in Mexico.

Petroglyphs are often associated with prehistoric societies, and their subject matter includes both real events and abstract ideas. Various theories have been put forward to explain the potential functions of these petroglyphs, though such interpretations are dependent on many factors, including the images depicted, the location of the petroglyph, and its age. Some petroglyphs, for instance, are believed to have had cultural and religious significance, while others were thought to be a form of symbolic communication. Yet others are thought to be astronomical markers, maps, or a precursor to writing.

Some of the petroglyphs at Boca de Potrerillos are thought to be astronomical markers, maps, or a precursor to writing. (theneonjaguar /Adobe Stock)

Some of the petroglyphs at Boca de Potrerillos are thought to be astronomical markers, maps, or a precursor to writing. ( theneonjaguar /Adobe Stock)

The rock art at Boca de Potrerillos is mostly found on the eastern flank of the El Antrisco and La Zorra mountains. This is one of the three main topographic divisions of Boca de Potrerillos, the other two being an “extended alluvial fan located on the eastern part of the site”, and another on the site’s western side. In the former, the archaeological finds consist of “the remains of hundreds of prehispanic hearths called fogones and thousands of carved lithic and grinding artifacts, which are widely dispersed on the surface”. The same kind of artifacts are found in the latter, though on a smaller scale.

According to one source, over 4000 pieces of rock art have been recorded at the site. Another source, however, claims that the number of petroglyphs at Boca de Potrerillos is estimated to be between 6000 and 8000. Yet another source claims that there are between 8000 and 10,000 petroglyphs at the site. Despite these differences in number, it is clear that the works of art were not created all at once, but over a period of time. This is due to the fact that the rocks display different levels of patination and exposure to the elements.

Interpreting the Boca de Potrerillos Petroglyphs

The vast majority of the petroglyphs at Boca de Potrerillos are found on rock boulders or rock panels, which makes them immobile works of art. Most of the designs of the petroglyphs, up to 80%, according to one source, are abstract geometric figures.

Other designs include natural elements, such as rain, the stars, and the Sun. This suggests that the petroglyphs’ creators practiced some sort of cult involving the natural elements. Yet other designs include figures of shamans, plants, animals, and artifacts. It is also suggested that these petroglyphs have a cultic function, “probably related to ideological reproduction of local indigenous groups, and with aspects of a ceremonial nature such as hunting and fertility.”

Other designs include natural elements, such as rain, the stars, and the Sun. (Biologo Jorge Ayala/CC BY SA 4.0)

Other designs include natural elements, such as rain, the stars, and the Sun. (Biologo Jorge Ayala/ CC BY SA 4.0 )

Another interpretation of these petroglyphs is that they served an astronomical purpose. In general, the petroglyphs were made in such a way that they are oriented towards the sunrise. The site also has a “natural orientation to the cardinal directions and functions as a solar horizon calendar.”

Moreover, it has been argued that the creators of the petroglyphs had a reasonable amount of knowledge regarding the heavens and celestial events. Such knowledge would have been important, as it would have been often used by the hunter-gatherers who lived in the area in their daily lives. Researchers have determined that the astronomical knowledge possessed by the creators of the Boca de Potrerillos petroglyphs would have included a familiarity with the equinoxes and solstices, eclipses, and passing comets.

While most of the petroglyphs at Boca de Potrerillos are immobile, the site has also produced a small group of portable petroglyphs, which are also referred to as mobiliary art . An article from 1996 asserts that the mobiliary art of Boca de Potrerillos represent the “first portable art attributable to the Archaic hunters of northeastern Mexico who presumably occupied this region throughout prehistory.”

The article reports that 26 stones were found on the surface of two separate areas at the site. 17 of the stones were found in an area called Coconos, while the other nine were found at a place called Loma San Pedro. Based on radiocarbon dating, the former area is believed to have been occupied around 5,000 years ago, whereas the latter area was occupied between 230 and 950 years ago.

Both groups of petroglyphs were made of sandstone, which is the locally available raw material. The production technique and design of the stones, however, are quite different. For instance, the stones from Coconos were “engraved with broad, deep linear and curvilinear designs made by pecking and smoothing of grooves”, whereas the ones from Loma San Pedro have “simple linear cross-hatching”, which were made by scratching.

Drawing of some of the portable rock art found at Boca de Potrerillos. (Herbert H. Eling)

Drawing of some of the portable rock art found at Boca de Potrerillos. ( Herbert H. Eling )

Considering that there were still many uncertainties regarding the stones at that time, the authors of the paper were not too keen to speculate too much about the nature and function of the artifacts. Still, some cautious speculations were made.

As an example, the authors point out that as the distribution of the mobiliary art of Boca de Potrerillos is limited, and that they were found only within certain areas of the site, it was speculated that these artifacts suggested specialized production, and that they were used “by a very small segment of the population, perhaps even an individual.” Nevertheless, the authors were also quick to point out that this speculation “hinges on ascertaining how the stones came to be in these locations, whether they were casually discarded or if they were used, kept, or cached in a specific place, only to be uncovered centuries or millennia later and dispersed.”

Apart from that, speculations may be made based on comparisons between the mobiliary art from other parts of North America with those from Boca de Potrerillos. For example, similarities have been drawn between the stones from Coconos and those from the Lower Pecos region in Texas. These similarities are said to be “consistent with prayers, rites, or offerings related to fecundity, rain-making, and regeneration of resources, often considered provinces in the female domain.”

Who Made the Boca de Potrerillos Rock Art?

The creators of the rock art at Boca de Potrerillos is another of the site’s unsolved mysteries. As mentioned earlier, the Spanish colonists, despite producing detailed accounts of the native peoples of Mexico, made no mention of any large civilization in that part of their colony. It is widely believed, however, that the rock art at Boca de Potrerillos were created by the Coahuiltecans.

This term does not refer to a single ethnic group of Native Americans . Instead, Coahuiltecan is better understood as a geographical term, as it encompasses the hundreds of small, nomadic hunter-gatherer societies who lived in the areas of southern Texas and northeastern Mexico.

Alternatively, it has been suggested that the petroglyphs were created by some other native American culture, such as the Aztecs , the Comanche, or the Chichimec. There is, however, insufficient evidence to support these claims.

Visiting and Preserving this Significant Archaeological Site

Boca de Potrerillos is without doubt one of the most significant rock art sites in Mexico. The site’s website claims that Boca de Potrerillos is the “only cave area with a presidential declaration in northeast Mexico.” Another source mentions that the site is on the Tentative List of UNESCO’s World Heritage Site. Due to the importance of the site, measures have been taken to protect it.

For instance, Boca de Potrerillos is included in INAH’s Public Register of Monuments and Archaeological Zones. This means that the boundaries of the site are legally defined, and “marked on the ground by 10 boundary markers in form of piles of stone”. Additionally, the site is surrounded by a mesh fence, and may be accessed via two entrances on opposite sides.

The protection of the archaeological site also involves the local population. Meetings with local communities, for example, were held to inform them about the judicial and legal measures protecting the site. In addition, people from these communities were employed as site guardians and watchmen.

Today, Boca de Potrerillos is not only an archaeological site, but also a tourist attraction. Only a small part of the site, however, is opened to the public . The rest of the site is a buffer zone, which is meant to protect the site from the negative impacts of tourism.

Moreover, this buffer zone ensures that more archaeological investigations may be conducted in the future. Hopefully, this will help to enhance our understanding of Boca de Potrerillos and its fantastic rock art.

Top Image: Petroglyphs at boca de Potrerillos, Nuevo León México. Source: theneonjaguar /Adobe Stock

By Wu Mingren

References

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