Landscapers were digging a hole for a pond in the back yard of a Boulder, Colorado home when their equipment uncovered a cache of 83 stone tools that had been buried by a person in the Clovis era. What is even more fascinating is that some of the tools had protein residues from extinct animals (camels, horses, sheep, bear), probably as a result of the original owner having used the scrapers to strip meat and/or prepare hides for use. Those protein residues allowed the cache to be dated to about 13,000 years before the present.
The Mahaffy Cache consists of 83 stone implements ranging from salad plate-sized, elegantly crafted bifacial knives and a unique tool resembling a double-bitted axe to small blades and flint scraps...Photo credit here. This link includes a video.
The artifacts were buried in a coarse, sandy sediment overlain by dark, clay-like soil and appear to have been cached on the edge of an ancient stream, said Bamforth. "It looks like someone gathered together some of their most spectacular tools and other ordinary scraps of potentially useful material and stuck them all into a small hole in the ground, fully expecting to come back at a later date and retrieve them."
A 2008 study led by the University of Oregon offers evidence that a cadre of comets exploded over North America about 12,900 years ago, triggering massive fires that caused the extinction of ice-age mammals and perhaps even the Clovis people.