These geologic entities c
These geologic entities come in fountain and cone varieties. Two of these named "Vent" and "Turban" help predict the activity of one of these named "Grand." They are caused near fissures and cavities in the rock when magma near the Earth's surface (*) heats a source of water. Mostly found in the Western United States and Iceland, for 10 points, name this type of violently erupting hot spring, such as Yellowstone's Old Faithful.
These geologic entities come in fountain and cone varieties.
geyser (prompt on "(hot) spring")