Helens had the shape of a conical, youthful volcano sometimes referred to as the Mount Fuji of America. During the eruption the upper m 1, ft of the summit was removed by a huge debris avalancheleaving a 2 x 3. It is primarily an explosive dacite volcano with a complex magmatic system.
Volcanos in the range include Mount St. HelensMount Rainierand Mount Shasta. The Cascades are part of the " American Cordillera ", the almost continuous spine of mountains which runs right down the western side of the Americas.
The highest mountain in the cascades is Mount Rainier at 14, feet or 4, metres. Wikimedia Commons has media related to Cascade Range. Geology[ change change source ] The Cascade range was formed by thousands of small, short-lived volcanoes that built a platform of lava and volcanic debris.
Rising above this volcanic platform are a few strikingly large volcanoes, like Mount St. Helensthat dominate the landscape. The process of continental drift is fuelled by the production of sea-floor material at the mid-Atlantic trench.
The landmasses of the Americas have buckled the edges of the Pacific plates, resulting in the continual volcanic build-up of mountains on the western side of the continents.
The Cascade Volcanic Arc made its first appearance 36 million years ago. The major volcanic peaks today were born in the last 1.
More than 3, vents erupted during the most recent volcanic episode that began 5 million years ago. As long as subduction continues, new Cascade volcanoes will continue to rise.
The water vapor rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly formed magma rises toward the Earth's surface to erupt, forming a chain of volcanoes.Mount St.
Helens and Mount Hood provide excellent depositional records of the broad spectrum of volcanic hazards that involve the flow or fall of volcaniclastic particles.
Sep 7, - Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal background levels of activity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St.
Helens, and Mount Adams in Washington State; and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon. 1 - During the past 4, years, Mount St.
Helens has erupted more frequently than any other volcano in the Cascade Range. 2 - Most of Mount St. Helens is younger than 3, years old (younger than the pyramids of Egypt). After the eruption of Mount St.
Helens in , the U.S. Geological Survey (USGS) intensified its monitoring of active and potentially active volcanoes in the Cascade Range. Monitoring of the Lassen area includes periodic measurements of ground deformation and volcanic gas emissions and continuous transmission of data from a local network of.
A Personal Look at Mt. St. Helens: Read a more personal perspective on the eruption of Mt. St. Helens from a person who grew up within sight of the Cascade range. Facts and Details on Mt.
St. Helens: Quick facts and statistics are offered about Mt. St. Helens. 1—During the past 4, years, Mount St. Helens has erupted more frequently than any other volcano in the Cascade Range. 2—Most of Mount St. Helens is younger than 3, years old (younger than the pyramids of Egypt).
3—Some Native American names that refer to smoke at the volcano include.