A stone tool found in a dig site in southeastern Oregon, the Rimrock Draw Rockshelter, could point to an earlier presence of human settlement in the western US than was previously thought.

The tool is made of orange agate and was found in a deposit of volcanic ash that dates back about 16,000 years. Archaeologists working at the site posit that if the layers of deposit were undisturbed that would make the tool older than the volcanic ash, one of the oldest artifacts ever found in North America.

Patrick O'Grady, archaeologist with the University of Oregon Museum of Natural and Cultureal History, joins the show.