An ancient petroglyph displayed on Hidalgo Plaza, the Piedra Historica is one of the more intriguing objects in a town full of quiet history. The carved rock was recovered from a nearby ranch and placed here so locals and visitors could study it. The engravings show a series of lines and channels that some researchers interpret as a schematic map of the irrigation canals that the Opata people used to farm the Sonora River valley. Whether or not that reading is correct, the stone is genuinely old and the mystery is genuine.
Piedra Historica
A story
The boulder was found on a ranch in the surrounding hills and moved to the plaza for safekeeping. Archaeologists believe the carved lines may represent an ancient irrigation canal system — a working map etched in stone by the Opata people who managed the river valley's water supply centuries before the Jesuits arrived.