landslides and volcanic development in the evolution of volcanic terrain. A vast piece on the north side of Mount St. Helens dropped and formed a jumbled landslide environment several kilometers away from the volcano. Pyroclastic flows and lahars moved across the countryside. Parallel episodes have also happened at Mount Shasta and other Cascade volcanoes in prehistoric times. List of volcanoes Washington has a majority of the very highest volcanoes, with 4 of the top 6 overall, although Oregon does hold a majority of the next highest peaks. Even though Mount Rainier is the tallest, Mount Shasta in California is the largest by volume, followed by Washington's Mount Adams. Below is a list of the highest Cascade volcanoes: See also List of volcanoes in the United States Volcanology of Western Canada List of volcanoes in Canada Geology of the Pacific Northwest Canadian Cascade Arc Milbanke Sound Group Notes References Skiing the Cascade Volcanoes – Introduction to the Cascade Volcanoes External links USGS Cascades Volcano Observatory Smithsonian Institution Global Volcanism Program Volcanoes + + + + Volcanic arcs Volcanic belts Cascade Range Cascade Range Eocene volcanism Miocene volcanism Pliocene volcanism Pleistocene volcanism Holocene volcanism