Saturday, August 1, 2020


Petroglyph at Caborca, Sonora, Mexico.
Photograph Margaret Berrier, 1993.

Comets have always fascinated humans whether seen as good omens or evil portents. As I am writing this Comet Neowise (C/2020 F3) is overhead in the evening sky under the Big Dipper. A sight like this would have been even more impressive to people in a dark sky with no light pollution centuries ago. I recently received a picture from Margaret Berrier of a petroglyph panel near Caborca, in Sonora, Mexico, which appears to include a possible comet image.

Comet Neowise, Northern Arizona, July 18, 2020, from Flagstaff, AZ. Photograph Austin Young, online image.

Margaret is an independent rock art researcher who lives in New Mexico and took the photograph in 1993. Indeed, the panel can be interpreted to show a comet passing a crescent moon. The rock art is attributed to the Trinchera Tradition, which is dated to between 750 and 1450 CE, with a range extending from the Gulf of California into northern Sonora. (Wikipedia) These people certainly were stone workers. Their culture is named Trinchera (trenches) after the rock terraces that they created up hillsides, believed to be used for residential areas as well as possibly agriculture (although why the name is not Terrazza for terraces escapes me).

Trincheras at Cerro De Trincheras, online photograph from

"Contemporaneous with the Hohokam of the river valleys of southern and central Arizona were pottery-making cultures adapted to the desert province of the Papagueria of southern Arizona and northern Sonora. A distinctive complex known as the Trincheras culture was centered in the Magdalena and Altar valleys of northern Sonora, the name Trincheras being derived from the terraced hillsides or 'fortified' hills that are the most obvious architectural feature of these sites. These desert groups probably had roots in the Cochise and their cultural systems reflect different adaptive responses to the local environment. Subsistence in the dry Papagueria was based primarily on hunting and gathering." (Schaafsma 1980:99)

What relationships existed between Trincheras and Hohokam has been argued at length. Some consider Trincheras to be a manifestation of a "Desert Hohokam" complex while others deny any relationship at all. (Schaafsma 1980:100)

"The last view, however, is not borne out by the rock art. Shared petroglyph elements and stylistic traits throughout the entire area suggest that all the various populations, including the Hohokam, were in communication and participated in shared ideas. One of the prime mechanisms for this interaction may have been the shell trade from the Gulf of California. The Trinchera people themselves were the major suppliers of shell for the more northerly Hohokam and such a trade would have been an important means of facilitating direct communication with the north." (Schaafsma 1980:101)

As we now know there was considerable south-north contact between the cultures of the desert southwest, especially commercial contact and trade.

"The rock art of the Trincheras culture is less well known than that of the Hohokam. Nevertheless, petroglyphs are fairly common in the Magdalena-Altar riverine region. - - -Design elements consist of anthropomorphic, zoomorphic, and geometric figures in the Hohokam style. On Cerro las Trincheras, the first of these sites to be so named, are representations of quadrupeds, spirals, and other abstract designs, both curvilinear and rectilinear. From Caborca and a Trincheras site near La Nariz east of Sonora, Lumholtz (1912) illustrates further Hohokam-like designs - again spirals, a set of frets, lizards with  the typical central bulge, and a pattern of interlocking scrolls." (Schaafsma 1980:101)

"Differences between the Trincheras petroglyphs of Sonora and the Arizona Hohokam lie primarily in the degree of refinement in design and in technical matters, the Sonoran figures generally excelling in these aspects." (Schaafsma 1980:101)

Petroglyph at Caborca, Sonora, Mexico. Photograph Margaret Berrier, 1993.

This panel, which includes a possible comet image, also shows an orb which can be interpreted as a crescent moon (a comet would be seen, of course, in the night sky). All-in-all this seems a fairly reasonable assumption. Which comet would be represented, on the other hand, is probably impossible to determine. During the time span of the Trinchera complex there are historical records from other cultures of comets appearing and we can guess it was possibly one of those.

For instance in 837 AD, Halley's comet approached as close as 3.2 million miles to the Earth, its tail stretching some 60 degrees across the sky (this is 1/3 of the distance across the sky from horizon to horizon). This appearance was recorded in annals in China, Japan, Germany, and the Byzantine empire. Halley's also was recorded subsequently in 989, 1066, 1145, 1222, and 1301 AD. (Wikipedia)

The 1066 AD appearance of Halley's comet is probably the source of the painted comet image above the Peñasco Blanco trail in Chaco Canyon, New Mexico (Faris 2010) and as the most impressive on record is probably a logical candidate for the inspiration of this Trinchera petroglyph.

NOTES: Thank you to Margaret Berrier for sharing this interesting photograph as well as permission to use it.

Some images in this posting were retrieved from the internet with a search for public domain photographs. If any of these images are not intended to be public domain, I apologize, and will happily provide the picture credits if the owner will contact me with them. For further information on these reports you should read the original reports at the sites listed below.



Faris, Peter

2010   Halley's Comet Pictured in Chaco Canyon, November 20, 2010,

Schaafsma, Polly

1980   Indian Rock Art of the Southwest, School of American Research, Santa Fe, pp. 99-101.


History of Sonora,

Halley's Comet,