Geologic map of Newberry Volcano, Deschutes, Klamath, and Lake counties, Oregon

Newberry volcano, one of the largest Quaternary volcanoes in the conterminous United States, is a broad shieldlike landform with a summit caldera 7 km across. It comprises the products of thousands of eruptions, at least 25 of which occurred during the last 10,000 years (Holocene Epoch). Eruptions have occurred as recently as 1,300 years ago, but isotopic ages indicate that the volcano began its growth as early as 0.6 million years ago. Thus, its long history and recent activity indicate that Newberry volcano is likely to erupt in the future.