Leaving an Impression for the Ages: Footprints from a Family Walk through the Mud at Least 2,500 Years Ago in Arizona are Reconnecting Local Tribes with their Past

About 2,500 to 3,000 years ago some early North Americans walked in Arizona and left their footprints in the clay and mud. The prints are still there, petrified now, and viewable at a modern construction site in Tucson.

Archaeologists working at the site of a new bridge and highway connection say the prehistoric footprints belonged to people who lived and farmed in the area part of the time and moved around at other times.

“It’s incredible, and we’re so excited,” Ian Milliken, an archaeologist with Pima County who is working on the project, told Ancient Origins. “There’s been an incredible outpouring of support from the public.”

Members of the Tohono O’odham Nation, whose reservation is in Arizona, have been some of the visitors to the site. A group of high-schoolers from the tribe also plans to make the trip to see the footprints next week. Other tribes have been invited to view the ancient prints as well.

Mr. Milliken said that there are 13 tribes with ancestral ties in the area, but whether the modern people are related to the people who left the footprints can’t be known because there is no DNA evidence from the prehistoric period.

Another one of the footprints (ArchaeologySouthwest.org photo)

Workers on the project have extracted two of the footprints in blocks and have taken castings of others so they can be replicated in a pedestrian showcase near the roadway for posterity, he said.

Doug Gann of Archaeology Southwest wrote a report about the find on the company’s website, saying:

“Archaeologists from SWCA (Suzanne Griset, Principal Investigator) and Pima County observed the footprints of women, men, kids, and dogs, as well as three-dimensional remains of irrigation canals, field boundaries—even planting pits. All marked in a single muddy surface that dried out and hardened into solid adobe, which was then, some days later, buried in a flash flood so intense the entire area was blanketed in clean sand before the previously dried mud record could melt.”

Mr. Gann also said that it must have been a wet day on the farm when the people left the prints.

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Dan Arnit of Innovative Excavating discovered the ancient footprints, possibly the oldest north of Mexico in the American Southwest, while working at the site. He saw a heel and scratched away dirt and sand to reveal toes and an entire set of footprints. More excavation in the vicinity turned up 20 to 30 sets of footprints.

The people who made the footprints were of the early agricultural period and hadn’t developed ceramics yet. They were of the Stone Age and yet had marks of civilization. Discoveries at the site are evidence that the people had a technological sophistication that researchers did not know people of that time and region had developed yet.

This aerial shot shows the construction site where the prehistoric footprints were discovered. (Photo by ArchaeologySouth.org)

“It’s a transition era from a lifestyle defined by hunter-gatherers to a settling down,” Jerome Hesse of SWCA Environmental Consultants told Tucson.com

Excavations at the site have revealed two field cells and two parallel channels that fed water to the fields. Archaeologists have also found an earthen barrier that may have redirected water flow from the river. Mr. Milliken told Ancient Origins that the field cells are in the construction area, but the site is much bigger than the project area, so some of the site’s features can be preserved for future study.

Research in past years has shown that the course of the Rillito River has shifted as much as a mile over the intervening years. So it’s possible the river bank, now about a kilometer (half mile) away, was a lot closer to the crop field when the footprints and irrigation works were made.

Rillito River & Rincon Mountains. Old Fort Lowell, Tucson, Arizona. (Raquel Baranow/CC BY 2.0)

“This is a perfect place for irrigation agriculture ,” Mr. Milliken told Tucson.com. “They were brilliant engineers.”

Researchers are unsure how the people lived or organized their society, but Jerome Hesse said they likely lived near the irrigated fields and other places in the region.

Ancient Origins asked Mr. Milliken if researchers know what crops the people grew there.

“As for your question related to crops and pollen, we have taken a large amount of samples from the field, and hope to be able to answer these questions when we begin analysis. We are currently wrapping up fieldwork (next week or two), following which we will begin our analysis, which will involve running a set of the samples,” he wrote in e-mail.

Interactive 3D models of the footprints and site can be found at: http://www.archaeologysouthwest.org/what-we-do/investigations/sunset-road-footprints/

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The Arizona footprints are impressive, and more information will likely arise from their discovery, however they are not the oldest in North America. In 2014, researchers discovered fossilized footprints far north of Arizona, on Calvert Island, off the coast of British Columbia in Canada, that could be more than 13,000 years old. If they are that old, it would make them the oldest footprints discovered in North America.

This is the oldest known footprint in North America, discovered on Calvert Island in British Columbia and dating back more than 13,000 years ago. (Photo credit: Joanne McSporran)

The footprints were discovered below the shoreline on Calvert Island, a remote island off the coast of central British Columbia. The island can only be visited by boat or a seaplane. The first footprint on the site was discovered in April 2014. It was found pressed into grey clay beneath other layers of sediment. This discovery prompted the team of archaeologists, drawn from a number of locations including the University of Victoria, Hakai Institute and Heiltsuk and Wuikinuxv First Nations, to return to the site in May 2015 to conduct a longer and more extensive excavation. On this occasion, 12 other footprints were discovered, believed to be those of a man, woman, and child.

The British Columbia footprints are estimated to be at least 13,000 years old, making them 800 years older than others found nearby in a cave on Haida Gwaii.

Evidence of an ancient campfire was also found nearby, within a hearth of rocks, consisting of a pile of ash and soot. Radiocarbon dating indicates these remains could be around 13,200 years old. A stone tool was also found near the fire.

Featured image: Hohokam people working in gardens with irrigation canals. (Duke Manor) Detail: Outline showing one of the footprints found at the site in Tucson, Arizona. (Daily Mail)

By Mark Miller