Cerro de Trincheras Trail, Museum & Petroglyphs South of the Border in Sonora, Mexico
The Cerro de Trincheras is an extraordinary prehistoric archaeological site located just outside the village of Trincheras in the northwest Mexican state of Sonora. The site opened to the public in December 2011 and includes an interpretive trail and an extensive visitor’s center (museum). The site is under the auspices of the National Institute of Anthropology and History (INAH).
My husband and I visited the site by taking a day-trip tour south of the border into Mexico (when the border was open before the COVID-19 pandemic), departing from Nogales, Arizona. The tour was organized by Linda Rushton from Ambos Tours of Arizona, based in Nogales, Arizona. We were part of a small group of nine people total. We left Nogales, Arizona, crossed the border into Nogales, Sonora, at 8 a.m., and, after a couple of stops, we reached Trincheras just before noon.
The Cerro de Trincheras site is the remains of 900 hillside terraces with retaining stone walls ranging from 4 inches to 10 feet tall, dating from an early culture between AD 1300 and 1450. “Cerro” in Spanish means hill or mountain, and “trincheras” was the Spanish term for entrenchments or fortifications, as that is what the hillside terraces reminded the early Spanish explorers. The name of this settlement is attributed to Captain Mateo Manje, who accompanied Father Francisco Kino to the Magdalena Valley. The soldier said that they looked like military trenches.
The stone terraces at Cerro de Trincheras were used for agricultural and housing purposes, where prehistoric farmers of the Sonoran Desert lived. The first settlers arrived in the area about 13,000 years ago, and the hunters and gatherers adapted to the Sonoran Desert environment about 10,000 to 8,000 years ago (www.lugares.inah.gob.mex ). The site excavation took place between 1995 and 1996 and was a bi-national effort. Research showed that over 1,000 people lived there, and creating the terraces was a major investment of labor (Cerro de Trincheras, Randall McGuire & Elisa Villalpando, Archeology in Tucson, Winter 1998).
When we visited, a new short-term pottery exhibit was on view. The beautiful display included four polychrome pots discovered by archaeologists at the site, and new pottery created by local youth, using the ancient clay type and methods.
Among the other museum exhibits, I found most interesting the arrowhead points, finds from the local Clovis culture around 5,000 years ago. The name ‘Clovis’ is derived from Clovis, New Mexico, where these type of spear points were first found in 1929. On exhibit are biface, fluted biface and projectile points from La Cochera and La Playa Municipali
ties of Trincheras and the geo-archeological investigations at Fin Del Mundo, all dating from 5500 to 4100 years ago. Points from La Playa date to the early Agriculture Period (1500 to 850 BC), which continued into the early Ceramic Period (AD 50-500). The rich blade industry artifacts include cores, flakes, and blades. Local materials used include vitrified basalt, quartzite, rhyolite, obsidian, and chert (for in-depth details, read Clovis - At the Edge of New Understanding, A. Smallwood, T. Jennings, 2015).
I was also very attracted to the local jewelry-making finds of shell bracelets and beads from the nearby La Playa site, which had a thriving shell jewelry manufacturing tradition. Marine shells were collected in the Gulf of California and utilized by the communities of Early Farmers to adorn their bodies. Among them are cone shells and Glycemeris shells (large saltwater bittersweet clams) - a popular trade item among the Hohokam people of the Sonoran Desert; some shell fragments are even engraved. Archeologists have recovered examples of all manufacturing process stages of shell loops (circles) for bracelets and beads. The known method of shell-bracelet manufacturing from the La Playa site, involved “marking off the shell exterior with deep, regular, short scratches, and the artisan sawed them with a sharp flaking tool. When the grooves were deep enough, the artisan tapped the center with his hammerstone, and the core fell out. Then, the ragged edges were ground and smoothed” (Shell Bracelet Manufacturing, Christine Virden-Lange, Archeology Southwest, 2017).
Walking through the museum, we followed the outside trail, where interpretive signs guide visitors through the terraced hills. The hill’s occupation only lasted about 150 years, and much of the evidence has disappeared, but the terraces’ stone walls remain as silent witnesses. When we visited in the summer, all terraces were covered by green vegetation due to monsoon rains. A few fellow tour participants braved the heat and hiked all the way to the top of the hill to see the Plaza del Caracol (the snail shell), which has semi-circular walls and a spiral-shaped access corridor.
Andy and I walked to La Cancha (The Court), a large plaza area for public events. The Court is the name modern archeologists gave to this public space, which never had a roof, possibly used by the ancient inhabitants for ceremonies. The interpretive signs read, “As in modern Indian ceremonies in northern Mexico, dancers probably used the flat space, and musicians and singers accompanied them from the circular structure.” We also enjoyed the petroglyphs area, where various images are carved on the rocks, occurring isolated or in groups. Designs include animals, human figures, and geometric forms.
The Cerro de Trincheras is a wonderful site, definitely worth visiting. Visitors can learn about this agricultural community and the Sonoran Desert’s pre-Hispanic occupation that was much more complex than previously imagined. Most exhibits are both in Spanish and English. All museum personnel were wonderful, happily sharing their knowledge about the site. It is open Wednesday through Sunday, 9 a.m. until 4 p.m., and there is no admission fee.
Find them at www.facebook.com/Zona-Arqueológica-Cerro-de-Trincheras, with a link to their website.