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Some of the stone tools revealed protein residues from bears, sheep, horses and camels. (photo courtesy CU Museum of Natural History)

Mysterious cache of prehistoric tools is ‘stunning, beautiful stuff’

By Ruthanne Johnson

If you didn’t know better, you’d think you were standing in front of some amazing sculpture in St. Peter’s Basilica or the Louvre. A white backdrop and the light-blue coloring on the walls of CU’s Museum of Natural History draw your eye to a series of delicately flaked stones, many of which are attached to vertical rods so they look as if they’re floating. Some are shaped like arrows. Others are round and flat, resembling rudimentary skinning knives. Soft spotlights highlight each depression, chisel mark and sharp edge.

“Every archaeological find is a small miracle.
What are the chances that people today will dig where people long ago deposited their things? Rare!
And the older the site, the less likely its discovery. This makes the Mahaffy Cache find truly extraordinary.”

—CU professor Doug Bamforth

You realize as you’re standing there that some ancient craftsman worked deftly, diligently to create these hunting and butchering tools for animals long gone from the Boulder Valley.

The 83 artifacts on exhibit at the museum were found in the spring of 2008 by landscapers moving dirt to make room for a koi pond in the backyard of Boulder
resident Patrick Mahaffy. One of their shovels hit something that sounded different from the surrounding soil and rock, and when one of the workers carefully scooped away the soil, there was this cache of uniquely chiseled stones packed together in a pit 3 feet square. Mahaffy knew as soon as he saw the stones they were something special, and contacted CU’s department of archaeology.

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Anthropologist Doug Bamforth (left) and Patrick Mahaffy in Mahaffy’s Boulder yard, where 83 stone objects had been buried.

“I went out there the next day and was just amazed,” remembers CU Boulder anthropology professor Douglas Bamforth. “It’s stunning, beautiful stuff—and I knew it was unique in my life experience to see something like this. I mean, you just don’t find tools like that anywhere.” The tools underwent a series of basic studies in the following year—such as measuring and inspecting to determine how they’d been made—and the surrounding soil was radiocarbon dated to about 1,000 years old. “That told us the cache couldn’t be younger than that,” Bamforth says.

Then the tools took a trip to California State University in Bakersfield, where they were tested for animal-protein residue. “We identified sheep, bear, horse and camel. One tool with each of those. No tool with more than one.” The findings told scientists the cache was at least 13,000 years old. Besides modern-day horses and camel-family animals like llamas and alpacas, which arrived more recently than 1,000 years ago, these mammals haven’t been around since the Pleistocene, when prehistoric Clovis peoples roamed North America. “We don’t know much about these early people, so anything we can add to that picture is important,” Bamforth says.

The Work of a Master?

The cache provides evidence that these early people, ancestors of today’s Native Americans, preyed upon a wider variety of animals than previously thought. And the locations of the stone used to make the tools—the Uinta Mountains in northeastern Utah, the Yampa River Valley and Sand Wash Basin near Craig, and up into Middle Park—demonstrates a clear path across Colorado. And they probably did it fairly quickly, Bamforth says. “As you use a stone tool, it gets dull and you have to reflake the edges and it gets smaller and smaller and changes shape. The user eventually throws it away when it’s no longer good enough to use.”

‘Archaeology is stones and bones.
Study and imagination give it meaning, and shed light on human life of the past.’
—CU professor Doug Bamforth

The cache also shows knowledge of the area. The softer, flakeable rocks were systematically gathered from known locations and then cached where they could be found. The Boulder cache was buried near the bank of Gregory Creek, which flows from behind the northernmost Flatiron. “All you would have to do is go to that place and follow the creek down to whatever landmark was there at the end of the Ice Age. It’s a findable, describable place, and that helps to explain the whole idea of cacheing it.”

As far as what happened to those who buried the cache, there’s simply no way to know, Bamforth says. “They might not have needed it. Maybe they forgot. They could have died or moved on to a different place.”

The exhibit offers visitors information about the cache and Clovis peoples. But museum staff also wanted to tap into the intrinsic beauty of the tools and what local residents would be interested in learning about them. Working with a consultant, they conducted a survey before building the display in-house.

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Some of the stone tools on display revealed protein residues from bears, sheep, horses, and camels (above). (photo courtesy CU Museum of Natural History)

“What rose up out of those inquiries is that some of the tools are more finely crafted than they needed to be to do the work they were designed for,” says museum assistant director Sharon Tinianow. “The process used to shape these tools is called flint-knapping,” she explains, “where you take a really hard stone, a granite rock from a riverbed, for example, and strike it against flinty stone, like chert or quartzite, to create form and sharp edges.” Though there are hobbyists still flint-knapping today, no one can replicate these tools, she says. “Perhaps we’re looking at the work of a master craftsman.”

To highlight the tools’ workmanship, they’re displayed standing upright in a case, held by wire mounts for 360-degree viewing. Replicas of the four stones found with protein residue were created with a 3-D printer. Visitors can pick them up to feel their shape and weight.

Beyond the cache’s scientific and artistic value is the way the find has resonated within the Boulder community. “People think what archaeologists do is cool,” Bamforth says. “But this seems to go beyond that. People are finding this connection to the deep past really special.”

There has been a significant spike in museum attendance since the exhibit opened in early October, Tinianow says. Visitors’ responses have been nothing less than inspiring. “For some people it’s the connection of being able to hold the tools. Others are struck by how beautiful the tools are.” For others, it’s a deeper connection.

“What is inspiring is that these tools are from my ancestors over thousands of years ago,” writes one visitor, a Mountain Ute from Towaoc, Colo. “My relations had a plan. [Their] path of travel across is my known homeland. It is with great fortune that [the tools] were found intact in a cache.”

Attendance at the CU Museum of Natural History has risen sharply since the unique Mahaffy Cache went on display. “I have been to much larger natural history museums and seen many Clovis artifacts,” one visitor wrote, “but nowhere have I seen an exhibit on a scale where it was possible to so fully comprehend its significance or feel closer to the person or people who crafted them.” (photo courtesy of CU Museum of Natural History)
Attendance at the
CU Museum of Natural History has risen sharply since the unique Mahaffy Cache went on display. “I have been to much larger natural history museums and seen many Clovis artifacts,” one visitor wrote, “but nowhere have I seen an exhibit on a scale where it was possible to so fully comprehend its significance or feel closer to the person or people who crafted them.” (photo courtesy of CU Museum of Natural History)

On Exhibit

The Mahaffy Cache will be on exhibit through October 2016 at the University of Colorado Museum of Natural History, located in the Henderson Building at 15th Street and Broadway. Admission is free. For more information visit www.cumuseum.colorado.edu or call 303-492-6892.


Ruthanne Johnson contributes regularly to Brock Media publications. She is a staff writer for the Humane Society of the United States and is passionate about saving animals.