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Study: Chaco was largely ceremonial

Researchers say the land insufficient to feed large population



FARMINGTON — New research from a team headed by a University of Colorado scientist casts doubt on Chaco Canyon’s status as a significant yearround population center during the Anasazi era.

Larry Benson, an adjunct curator at the CU Museum of Natural History, as well as a hydrologist and geochemist, led a team of researchers that published its findings about the settlement’s food sources in the November 2019 edition of the Journal of Archaeological Science, a monthly, peer-reviewed academic journal.

Additionally, Benson maintains there is reason to believe Chaco was home to only a small, “caretaker” population on a year-round basis, filling up only occasionally for large ceremonial events that required large amounts of food to be imported.

The research largely confirms what Benson thought when he got his first look at Chaco Canyon — now known as Chaco Culture National Historic Park — decades ago. As a native Midwesterner who had grown up amid lush corn fields, he didn’t see any way that the arid territory surrounding the settlement could produce maize or other crops in significant amounts – and certainly not enough to feed the 2,300 people often cited as the population of Chaco during that era.

During a telephone interview on Jan. 10 from Boulder, Colorado, Benson said the research focusing on Chaco’s unsuitability for large-scale agriculture that was featured in the Journal of Archaeological Science paper didn’t break a lot of new ground, as much of it had been published before. But it did go into much greater detail, crunching large amounts of data that strongly support the idea that the area could produce only enough food on its own to sustain a very small population.

Only a minimal amount of maize could have been grown at Chaco because of its aridity, short growing season and the flooding of the valley floor that occurred frequently in the summer, Benson writes with his fellow authors, Deanna Grimstead, John Stein, David Roth and Terry Plowman.

Benson said it was clear to him that dryland farming was not a feasible option for Chaco residents during the prehistoric era, and he said there is no physical evidence that irrigation took place in the valley on a large scale.

“It would have taken a monumental ditch and berm system to prevent (summer monsoon) flooding and direct the flow of that water,” Benson said.

If such a system had been built, he said, “You should be able to see it now, and you can’t, so my position is, they didn’t.”

According to Benson’s research, even if Chaco residents had farmed 100 percent of the valley floor and the surrounding side valleys — a dubious proposition, he noted, estimating that only around 20 percent of that land is actually usable for agriculture — it could have supported a population of 1,000 people at most.

Additionally, the authors also write that 2,300 residents and their need for meat quickly would have eliminated the small and large animal populations, such as deer and rabbits, in the valley.

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