- USGS/Cascades Volcano Observatory, Vancouver, Washington Road Guides and Field Trips -- Not Necessarily Online -- Cascade Range and Other Volcanic Areas Central Oregon Columbia River Gorge and Vicinity Crater Lake, Oregon Mount Hood, Oregon Long Valley Vicinity, California North Cascades, Washington State Mount St. Helens, Washington State Sunset Crater, Arizona Cascade Range and Other Volcanic ...vulcan.wr.usgs.gov/Publications/road_guides_list.html