Archaeologists have unearthed all manner of Native American artifacts. One that has evoked considerable controversy is a site found at Fort Rock, east of the Cascades near Bend. Charcoals from a hearth there are thought to be more than 13,000 years old, exceeding earlier estimates of the period of human presence in the region by about 3,500 years. A sandal found at the same site dated at around 10,000 years old had been the previous standard-bearer.

Another significant find is a gallery of 5,000-year-old petroglyphs on the walls of a cave in the foothills just east of the Willamette Valley. Artifacts excavated from the site of the Oregon Country Fair near Eugene have been dated at 8,000–10,000 years of age.

Other finds include coastal and Rogue Valley digs where 9,000-year-old artifacts have been unearthed. Obsidian flaked in the Clovis style indicates that ice age people roamed the Rogue Valley as long as 11,000 years ago. The distinctive grooves in the obsidian mark it as a product of the Clovis big-game hunter culture. Researchers excavated a site at Indian Sands in Samuel H. Boardman State Park north of Brookings that yielded artifacts dating back more 12,000 years, making it the oldest known site of human activity yet found on the coast.

In 1999 the oldest house in Oregon, and possibly the United States, was discovered on the shore of Paulina Lake. The archaeological significance of this 9,500-year-old site might eventually be rivaled by finds in several Woodburn city parks, 35 miles south of Portland. In the summer of 2000, a human hair was found in 12,000-year-old soils of an ancient wetland, along with animal bones thousands of years old.