GRANTS PASS, Ore. (AP) — Archaeologists have uncovered a stone tool at an ancient rock shelter in the high desert of eastern Oregon that could turn out to be older than any known site of human occupation in western North America. 
 
 The find was announced Thursday by the U.S. Bureau of Land Management, which controls the land on which the site was found. 
 
 University of Oregon archaeologist Patrick O'Grady, who supervises the dig, says the Rimrock Draw Rockshelter outside Riley has not been fully excavated. But the tool, a hand-held scraper chipped from a piece of orange agate not normally found in eastern Oregon, was found about 8 inches below a layer of volcanic ash from an eruption of Mount St. Helens that has been dated to 15,800 years ago. The depth was about 12 feet below the surface. 
 
 Bureau of Land Management archaeologist Scott Thomas said that if the age of the site holds up to scrutiny, it would be the oldest west of the Rockies, and another predating the so-called Clovis culture, once generally believed to be the first people to migrate from Asia into North America. The earliest Clovis artifacts, known for distinctive and elegant stone points, are dated to about 13,000 years ago. 
 
 O'Grady called the find "tantalizing," but he added that they want to continue digging this summer to see whether the volcanic ash covers the entire area. 
 
 Donald K. Grayson, professor of archaeology at the University of Washington, said the scientific community would be skeptical. 
 
 "No one is going to believe this until it is shown there was no break in that ash layer, that the artifact could not have worked its way down from higher up, and until it is published in a convincing way," he said. "Until then, extreme skepticism is all they are going to get." 
 
 Two pre-Clovis sites are well documented and generally accepted by scientists, Grayson said. One is Paisley Cave, located about 60 miles southwest of the Rimrock site. The other is Monte Verde in Chile. Both are dated about 1,000 years before the oldest Clovis sites. 
 
 If the date of Rimrock holds up, it would put people at the site about 1,500 years earlier, at the end of the Pleistocene era, when mastodons, mammoths, camels, horses and bison roamed the area. 
 
 The find has yet to be submitted to a scientific journal for publication, but it has been reported in newsletters and at conferences, Thomas said. 
 
 Thomas found the site several years ago, while taking a break from carrying supplies to a session of the University of Oregon Archaeological Field School nearby that O'Grady was overseeing. 
 
 Thomas said he noticed an outcropping of an ancient lava flow, with some very tall sage brush growing in front of it, indicating very deep sediment deposits. The soil was black in front of the rock, indicating someone regularly built cooking fires there for a long time. An ancient streambed ran by, which would have given people more reason to stay there. And on the surface, he found a stone point of the stemmed type, found at sites both older and younger than Clovis. Similar points have been found at Paisley Cave 
 
 Volunteers looking around the surface found some 30 stemmed points, and the field school started excavations in 2011, O'Grady said. Uncovered above and below the volcanic ash layer were fragments of teeth believed to be from ancient camels. 
 
 Tests by Archaeological Investigations Northwest Inc. of Portland on blood residue on the agate scraper were consistent with the bovid family of animals, Thomas said. The most likely bovine animal living in Oregon at that time would have been an ancestor of the buffalo. ||||| PORTLAND, Ore. - 
 
 Near the Rimrock Draw Rockshelter outside of Riley in southeast Oregon, archaeologists recently discovered evidence suggesting one of the oldest known human occupations in the western United States, officials said Thursday. 
 
 Archaeologists with the Bureau of Land Management and the University of Oregon Archaeological Field School have been excavating at the Rimrock Draw Rockshelter since 2011. 
 
 Their discoveries have included a number of stone projectile points and tooth enamel fragments likely belonging to a prehistoric camel (Camelops sp.) that became extinct approximately 13,000 years ago. 
 
 But what has the archaeological community most excited is a small stone tool found below a layer of volcanic ash. 
 
 Near the bottom of a 12-foot deposit, archaeologists discovered a layer of ash that was identified as volcanic ash from a Mt. St. Helens eruption about 15,800 years ago. 
 
 Beneath the layer of volcanic ash, archaeologists discovered a small orange agate tool believed to have been used for scraping animal hides, butchering, and possibly carving wood. 
 
 A blood residue analysis of the tool revealed animal proteins consistent with bison, the most likely species being Bison antiquus, an extinct ancestor of the modern buffalo. 
 
 “The discovery of this tool below a layer of undisturbed ash that dates to 15,800 years old means that this tool is likely more than 15,800 years old, which would suggest the oldest human occupation west of the Rockies,” said Scott Thomas, BLM Burns District archaeologist. 
 
 Presently, Oregon’s Paisley Cave, also managed by the BLM, is considered home to the earliest known residents of North America based on human physical evidence. 
 
 In 2008, a team of archaeologists, led by Dr. Dennis Jenkins with the University of Oregon's Museum of Natural and Cultural History, discovered coprolites - dried feces - containing human DNA dated over 14,000 years old. 
 
 Dr. Patrick O’Grady, with the University of Oregon Archaeological Field School, has been directing the Rimrock Draw Rockshelter excavations since they began. 
 
 “When we had the volcanic ash identified, we were stunned, because that would make this stone tool one of the oldest artifacts in North America. Given those circumstances and the laws of stratigraphy, this object should be older than the ash,” said O’Grady. 
 
 "While we need more evidence before we can make an irrefutable claim, we plan to expand our excavation this summer and hopefully provide further evidence of artifacts found consistently underneath that layer of volcanic ash. That’s the next step,” he added, 
 
 The University of Oregon Archaeological Field School, in partnership with the BLM and volunteers from the Oregon Archaeological Society, will begin its fifth season this summer, offering students, researchers and volunteers invaluable field experience. 
 
 Stan McDonald, BLM Oregon/Washington lead archaeologist, explained the potential this discovery has for the archaeological community. 
 
 “For years, many in the archaeological field assumed that the first humans in the western hemisphere were the Clovis people – dating to around 13,000 years ago," McDonald said. "While a handful of archaeological sites older than Clovis cultures have been discovered in the past few decades, there is still considerable scrutiny of any finding that appears older.” 
 
 “With the recent findings at Rimrock Draw Shelter, we want to assemble indisputable evidence, because these claims will be scrutinized by researchers," he said. "That said, the early discoveries are tantalizing.” 
 
 Flickr photo album: https://www.flickr.com/photos/blmoregon/sets/72157651118216896/
– A small stone tool unearthed in eastern Oregon appears to be so ancient that the history of humans in the area may have to be rewritten, archaeologists say. The agate scraper found at a rock shelter was below a 15,800-year-old layer of ash from Mount St. Helens, making it potentially older than any other evidence of human occupation west of the Rocky Mountains, reports the AP. Analysis of the tool—which is made from orange agate not usually found in the area—revealed it had been used to butcher an animal believed to be the extinct buffalo species Bison antiquus, KTVZ reports. University of Oregon archaeologist Patrick O'Grady says the team plans to keep excavating the site after the "tantalizing" find, which may be older than any other find predating the Clovis people once thought to be the first in North America, NBC News reports. University of Washington professor of archaeology Donald K. Grayson, however, predicts there will be a lot of skepticism about the find. "No one is going to believe this until it is shown there was no break in that ash layer, that the artifact could not have worked its way down from higher up, and until it is published in a convincing way," he tells the AP. "Until then, extreme skepticism is all they are going to get." (Experts believe they have found evidence of a long-lost civilization in the Honduran rainforest.)