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Arizona archaeologist says she's found artifacts linked to famed 1540 expedition: "A history-changing site"

A Tucson archaeologist has unveiled a discovery in Santa Cruz County that she thinks could rewrite the history of the Coronado Expedition. Deni Seymour said she has unearthed hundreds of artifacts linked to the 16th century Spanish expedition, including pieces of iron and copper crossbow bolts, distinctive caret-headed nails, a medieval horseshoe and spur, a sword point and bits of chain mail armor.

The "trophy artifact" is a bronze wall gun — more than 3 feet long and weighing roughly 40 pounds — found sitting on the floor of a structure that she said could be proof of the oldest European settlement in the continental United States.

Francisco Coronado Exploration
Francisco Coronado on 1540 expedition from Mexico through American Southwest. 1905 lithograph of painting by Frederic Remington. Universal History Archive/Universal Images Group via Getty

"This is a history-changing site," said Seymour, who touts herself as the Sherlock Holmes of history. "It's unquestionably Coronado."

The independent researcher revealed her find on Jan. 29 in a sold-out lecture to more than 100 people at Tubac Presidio State Historic Park.   

Seymour is not disclosing the exact location of the archaeological site, but her general description in the Santa Cruz Valley places it at least 40 miles west of Coronado National Memorial, which overlooks the San Pedro River and the U.S.-Mexico border south of Sierra Vista.

In 1540, Spanish conquistador Francisco Vázquez de Coronado led an armed expedition of more than 2,500 Europeans and Mexican-Indian allies through what is now Mexico and the American Southwest in search of riches.

The two-year journey took them as far north and east as present-day Kansas and brought them into contact — and often conflict — with centuries-old Indigenous cultures along the way.

Though professional archeologists and amateur sleuths have puzzled over it for close to 150 years, Coronado's exact route through Arizona to the elaborate Zuni pueblos of northern New Mexico remains a mystery.

The consensus among scholars is that the expedition most likely followed the Rio Sonora through northern Mexico and the San Pedro River into what is now Arizona.

Seymour believes her discovery proves once and for all that Coronado and company actually entered Arizona along the Santa Cruz River before eventually heading east.

Deni Seymour

That puts her at odds with most researchers.

Bill Hartmann is an accomplished Tucson astronomer, who has also been investigating and writing about Coronado for more than 20 years. In 2014, the University of Arizona Press published his book on the subject, "Searching for Golden Empires."

"It sure sounds like she has a really exciting site," Hartmann said after attending Seymour's first lecture in Tubac. "The big question in my mind is whether it disagrees with the earlier interpretation of where the Coronado Expedition went. I don't think it undermines earlier thoughts that they came up the San Pedro."

New Mexico historian Richard Flint had a similar reaction: excited by Seymour's discovery, skeptical about her conclusions.

Flint and his historian wife, Shirley Cushing Flint, are among the world's leading experts on the expedition. In more than 40 years of research, they've written eight books and countless academic papers on the topic.

"I think Deni's finds are certainly fascinating and probably indicate the presence of the Coronado expedition," Flint said. "I don't think that that means the usual reconstruction of the route going north has to be abandoned. The evidence is very strong that they came up through the Rio Sonora."

Seymour said she once favored the San Pedro route, too. But that was before all these artifacts turned up in an entirely different river valley.

She said she first visited the site in Santa Cruz County in July 2020 and immediately found several caret-headed nails, "which in this area means without question you have Coronado."

She has been uncovering artifacts there ever since with the help of metal detectors and a crew of up to 18 volunteers, including several members of the Tohono Oʼodham tribe.

"The site keeps giving and giving," she said.

Relics have been unearthed across an area that stretches for well over half a mile. At minimum, Seymour said, it is the remains of a large encampment, but she suspects it is something more.

"What we have is a named place," she said, "a place named in the Coronado papers."

Seymour believes she has found the remains of Suya, also known as San Geronimo III because it was the third and northernmost location of a Spanish outpost established to support the expedition.

Along with the central structure where the wall gun was found, she said she has identified what appear to be six surrounding lookout stations, three of which show "clear evidence of being attacked."

The Spanish "had a major presence here, and they had major conflicts with the natives here," Seymour said. "And it's different natives than previously thought."

Based on the site's location and the items she has found, she is convinced the outpost was routed not by the Opata people who once dominated what is now Sonora but by the Sobaipuri, whose direct descendants include the Tohono Oʼodham at San Xavier.

Clusters of lead shot and distinctive Sobaipuri arrowheads tell the story of their final confrontation, which sent the Spaniards retreating back to the south.

"We have clear evidence of battle," said Seymour, who has written dozens of academic books and papers about the region and its early native inhabitants. "There's no question."

Excavation at the site has yielded more than 120 caret-headed nails and more than 60 crossbow bolts so far.

Those are the most "diagnostic" artifacts from the Coronado Expedition, Flint said, and to find so many crossbow bolts in particular is convincing evidence of a significant skirmish.

According to Flint, there are a number of written accounts by members of the expedition that reference Suya and the battle that led to it being abandoned. He said the loss of the outpost "sort of put the nail in the coffin" of Coronado's journey, because it cut him off from his main resupply and communication route.

The question of whether it qualifies as the first European settlement in the U.S. seems to depend on how you define the word settlement.

To Hartmann, Suya was "more like a struggling military garrison than a town," he said.

And it wasn't the first regardless, Flint added. By the time San Geronimo III was established, Coronado had already traveled deep into present-day New Mexico, where the expedition clashed with native people and lived for months in some of their captured pueblos.

"Everyone wants to be first. (This discovery) is important, even if it's not the first," Flint said. "Virtually anything that is found about the Coronado Expedition has the chance to shed new light on something that was not known."

Seymour is far less measured. As far as she is concerned, this discovery is so important, so game-changing that it could wind up as a national monument or a World Heritage Site someday.

"There are a lot of naysayers," she said. "I'm an archaeologist. I just go where the evidence is."

Seymour expects to publish the first of several peer-reviewed papers on her discovery sometime this spring. She said she has already received a few radiocarbon results and other dating methods to back her up, with more testing planned.

As for her recent public talks in Tubac, Seymour said she took the unusual step of selling tickets and publicizing her work early to raise money for a documentary that's being made about the discovery by Tucson-based Frances Causey Films.     

"As archaeologists, we get to see the coolest stuff" and go to places others can't go, she said. "(The documentary) is important so people can see and understand the discovery process."

Just over $8,400 had been raised so far for the film, but the crowdfunding campaign was still well short of its $100,000 goal.

Seymour hasn't kept the dig site entirely to herself. Over the past year, she has shared photos of the artifacts with several experts, including the Flints, and invited a handful of fellow researchers out to see where she is working.

She said she only brings along people she can trust, and only on the condition that they not reveal the location or take anyone else there on their own.

Seymour knows she can't keep the site a secret forever, but she wants to protect it for as long as she can.

"We still have a lot of work to do," she said. "I don't want to be in competition with treasure hunters."

The longtime Southern Arizona researcher also claims to have found Coronado artifacts at two other spots about 6 miles apart in the San Bernardino Valley, roughly 100 miles east as the crow flies from her main site in Santa Cruz County.

She predicts these discoveries will eventually help pin down the exact route of the infamous expedition through Arizona.

"We have an anchor point now," Seymour said. "I think we're going to start finding a lot more Coronado sites."

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