Volcanic domes are steep, mound-shaped formations created by the slow extrusion of viscous lava from a volcano. Unlike explosive eruptions, these domes form when lava piles up near the vent, resulting in a dome-like structure. They can vary in size and shape, often appearing as rounded hills. These formations are typically made of rhyolitic or dacitic lava, which is thick and sticky. As the lava cools and solidifies, it can create a rugged surface with cracks and ridges. Some well-known examples of volcanic domes include Mount St. Helens in the United States and Novarupta in Alaska.