Lava domes are volcanic formations created by the slow extrusion of viscous lava. Unlike explosive eruptions, lava domes grow gradually as lava piles up near the vent, resulting in a dome-shaped structure. They can vary in size and shape, often appearing steep-sided and rugged. These formations are typically made of andesitic, dacitic, or rhyolitic lava, which is thicker and stickier than basalt. Over time, lava domes can collapse or produce pyroclastic flows, making them potentially hazardous. Notable examples of lava domes include Mount St. Helens in the United States and Novarupta in Alaska.