Mount St. Helens is a volcano. It is in the state of Washington. Its last eruption was in May of 1980. It had not erupted for over one hundred years before this. This eruption caused a lot of damage. It destroyed plants and habitats. An earthquake rumbled the land at the same time that the volcano erupted.
When the volcano erupted, it changed the land around it. Some trees were blown over. Other trees died where they stood. The volcano continued to erupt for six years. At first, the eruption was very violent. It slowed down with time. It built a lava dome. As the thick lava poured out, it piled on top of itself. The layers look like stacked pancakes. Mudflows traveled down the side of the volcano. These mudflows covered everything in their path. Ash from the volcano blew far away. Ash landed as far east as Minnesota. It landed as far south as New Mexico and Oklahoma.