Lava domes are volcanic formations created by the slow extrusion of viscous lava. Unlike fluid lava flows, the thick lava piles up near the vent, resulting in a dome-shaped structure. These formations can grow over time and may collapse or erupt, leading to potential hazards. Typically found in volcanic regions, lava domes can vary in size and shape. They are often composed of andesitic, dacitic, or rhyolitic lava, which is more viscous than basaltic lava. Famous examples of lava domes include Mount St. Helens in the United States and Novarupta in Alaska.