Carolyn L. Driedger Bobbie Myers 2008 Volcanoes have been erupting in the Cascade Range for over 500,000 years. During the past 4,000 years eruptions have occurred at an average rate of about 2 per century. This chart shows 13 volcanoes on a map of Washington, Oregon, and northern California and time lines for each showing the ages of their eruptions. application/pdf 10.3133/gip63 en U.S. Geological Survey Eruptions in the Cascade Range during the past 4,000 years reports