Researchers into the ancient human past are used to wandering the world in search of artifacts. But scientists at the University of Colorado said Wednesday that a major cache of Stone Age tools, believed to be 13,000 years old, had been found in a suburban backyard just six blocks from the campus in Boulder.
“I’m used to going hell and gone across the landscape to look,” said Douglas Bamforth, a professor of anthropology who analyzed the cache. “This time I walked.”
The 83 stone-cutting implements, some with enough blood residue on them to identify the animals they had been used to butcher, are believed to have belonged to a nomadic people who probably buried the tools for later retrieval, but never returned, Professor Bamforth said.
He added that the trove was one of only a handful of major tool caches ever found of that age in North America, and the first to identify protein residue from a now-extinct camel that the hunters had perhaps eaten before hiding their equipment and moving.
The homeowner, Patrick J. Mahaffy, said landscapers were digging out a space to build a fish pond last May when their shovels struck stone, unearthing the space where the tools had been buried. Reporting of the find was delayed until Wednesday to complete analysis, university officials said.
Mr. Mahaffy said that his area of Boulder, northwest of Denver, has been developed for decades — the house itself was built in 1969 — but that somehow that part of the yard had never been dug out.
He said he was struck by the beauty of the tools and also how well designed they seemed to be.
“They’re ergonomically perfect,” Mr. Mahaffy said. “They fit perfectly in your palm, and your fingers curl over just where they should.”