Volcanic mountains are formed by the eruption of magma from beneath the Earth's crust. When magma reaches the surface, it can create a variety of landforms, including shield volcanoes, composite volcanoes, and cinder cone volcanoes. These mountains often have steep slopes and can be found in areas where tectonic plates meet. As volcanic activity continues, layers of lava and ash build up, resulting in the growth of the mountain. Famous examples of volcanic mountains include Mount St. Helens in the United States and Mount Fuji in Japan. These mountains can be both beautiful and dangerous, as eruptions can pose risks to nearby communities.