February 25, 2009
BOULDER, Colo. -- Someone left their tools in a Boulder yard -- 13,000 years ago.The Clovis-era stone tools, uncovered last year, appeared to have been used to butcher ice-age camels and horses that roamed this part of North America until they became extinct.
The find was announced by the University of Colorado at Boulder on Wednesday.
Scientists examining the tools found protein residue from extinct camels and horse protein residue, said CU-Boulder Anthropology Professor Douglas Bamforth. The tool cache is one of only a handful of Clovis-age artifact caches that have been unearthed in North America, said Bamforth, who studies Paleo-Indian culture and tools.Named the Mahaffy Cache, after Boulder resident and landowner Patrick Mahaffy, the collection is one of only two Clovis caches -- the other is from Washington state -- that have been analyzed for protein residue from ice-age mammals, said Bamforth.
In addition to the camel and horse residue on the artifacts, a third item from the Mahaffy Cache is the first Clovis tool ever to test positive for sheep, and a fourth tested positive for bear.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 ax to small blades and flint scraps.
Discovered in May 2008 by Brant Turney, head of a landscaping crew working on the Mahaffy property, the cache was unearthed with a shovel under about 18 inches of soil and was packed tightly into a hole about the size of a large shoebox. It appeared to have been untouched for thousands of years, Bamforth said.Although the surface of the house lot had been lowered by construction work over the years, an analysis of photos from the Mahaffy Cache excavation site by CU-Boulder geological sciences Emeritus Professor Peter Birkeland confirmed the approximate age of sediment layer containing the Clovis implements. The site appears to be on the edge of an ancient drainage that ran northeast from Boulders foothills, said Bamforth.
"The idea that these Clovis-age tools essentially fell out of someones yard in Boulder is astonishing," he said. "But the evidence Ive seen gives me no reason to believe the cache has been disturbed since the items were placed there for storage about 13,000 years ago."The artifacts were buried in 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."Bamforth said he knew immediately that much of the stone used to craft the tools in the cache originated from Colorados Western Slope and perhaps as far north as southern Wyoming. The stone appears to have come from at least four distinct regions, including sites in Colorados Middle Park, south of Steamboat Springs, he said.
One of the tools, a "stunning," oval-shaped bifacial knife that had been sharpened all the way around, is almost exactly the same shape, size and width of an obsidian knife found in a Clovis cache known as the Fenn Cache from south of Yellowstone National Park, said Bamforth."Except for the raw material, they are almost identical," he said. "I wouldnt stake my reputation on it, but I could almost imagine the same person making both tools."
Climatic evidence indicates the Boulder area was cooler and wetter in the late Pleistocene era and receding glaciers would have been prominent along the Front Range of Colorado, he said."The kind of animals that were wandering around present-day Boulder at the end of the last ice age -- elephants, camels, huge bears and ground sloths -- are creatures we would expect to see in a zoo today."
"There is a magic to these artifacts," said Mahaffy. "One of the things you dont get from just looking at them is how incredible they feel in your hand --they are almost ergonomically perfect and you can feel how they were used. It is a wonderful connection to the people who shared this same land a long, long time ago."Mahaffy said the artifacts will likely wind up in a museum except for a few of the smaller pieces, which will be reburied at the cache site.