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Colorado State University archaeology Professor Christopher Fisher and geography Professor Stephen Leisz have used LiDAR (Light Detection and Ranging) technology to document thousands of architectural features from an ancient city in western Mexico that could help provide insights into the formation of the pre-Hispanic Purépecha (Tarascan) Empire and help unravel connections between complex societies and climate change.
The city, which predominately dates to between A.D. 1000 to A.D. 1520, may have held as many as 30,000 residents and features thousands of architectural remains, including pyramids, roads, buildings and the first documented ball court in the region. The urban center is located within the Lake Pátzcuaro Basin in Michoacán, Mexico, which was the geopolitical core of the Purépecha Empire at the time of European contact (A.D. 1520).
Fisher and Leisz, whose work has been funded by the National Science Foundation and the NASA Space Archaeology program, said the discovery could help researchers better understand the Purépecha civilization, which was a contemporary and rival of the Aztecs in central Mexico. The unique site, which covers more than 10 square kilometers, is located at 7,000 feet in elevation, a four-hour drive northwest of Mexico City.
“This is a very exciting discovery because it can document the growth of complex societies in the region and help determine social and environment factors that contributed to the formation of the Purépecha Empire,” Fisher said. “The city, at its height, was similar to a modern suburb, filled with neighborhoods where people lived their daily lives. This discovery will provide important clues into the formation of the empire as well as the impact of climate and environmental change, migration, changes in social complexity and other important issues.”
Fisher started surveying the site in 2008 and realized that the complex spatial arrangment, size and multi-functional nature indicated it was a city. After two seasons of intensive field work (approximately three months during the summer) Fisher’s team had documented more than 2,600 architectural features. Given the pace of the fieldwork, it would have taken at least a decade to fully document the architecture at the settlement.
That’s when Leisz, Fisher’s colleague in CSU’s Department of Anthropology, suggested LiDAR as a way to speed the surveying process. LiDAR uses pulses of infrared light from an airplane to allow researchers to “see” below the tree canopy all the way to the ground. The resulting images reveal structures that would otherwise take years to uncover.
“I was hesitant to use LiDAR because I could fund one full season of surveying for what it would cost to do the LiDAR survey,” Fisher said. “Thanks to Steve’s suggestion, it turned out to be a great decision. In 45 minutes of flying, the LiDAR team accomplished a decade’s worth of archaeological survey. In light of the LiDAR data, we can begin the excavation process much earlier than originally anticipated – perhaps even this summer.”
The LiDAR survey, performed by Merrick & Company from Aurora, Colo., revealed more than 20,000 architectural features and a highly organized city that is far more complex and included more people than previous research in the region has suggested. In addition, there is evidence for landscape features such as a complex water management system and intensive agricultural features.
Fisher’s work is part of “Legacies of Resilience: The Lake Pátzcuaro Basin Archaeology Project,” a long-term program of research by archaeologists, geologists and geographers from the U.S. and Mexico which is funded by major granting agencies and private donations. The goal is to better understand the development of the Purépecha Empire, the impact of climatic and environmental change on societies in the region, and to help build resilient strategies for modern land management.
The Purépecha were considered the most advanced metal smiths and among the finest craftsmen in Mexico. Like the rival Aztec, the Purépecha Empire was destroyed following European occupation in the early 1500s.