Volcanoes – Mount St. Helens Eruption 1980 Introduction: Mount St. Helens is situated in North America on the North American plate. It is the peak of the fold mountain range in North America. The fold mountain range was formed around 70 million years ago when a convergent plate boundary, Juan De Fuca Plate (Oceanic Crust), collided with the North American Plate (Continental Crust). The oceanic crust was forced downwards into the mantle causing it to turn into magma. …showed first 75 words of 956 total…

…showed last 75 words of 956 total…of ash. This is a good long term effect because the ash would give the soil many more nutrients. Vehicles could not be used because of the lack of visibility. However it was back to normal after a few weeks. Even though this eruption was a blow to tourism at that time, it was good for the long term because the area has been treated as a monument and many more people now visit it.