Fumarole and on the surfaces of lava flows and of thick deposits of pyroclastic flows. A fumarole field is an area of thermal springs and gas vents where magma or hot igneous rocks at shallow depth release gases or interact with groundwater. When they occur in freezing environments, fumaroles may cause fumarolic ice towers. Fumaroles may persist for decades or centuries if located above a persistent heat source; or they may disappear within weeks to months if they occur atop a fresh volcanic deposit that quickly cools. The Valley of Ten Thousand Smokes, for example, was formed during the 1912 eruption
Cave type of solutional cave. They were formed by HS (hydrogen sulfide) gas rising from below, where reservoirs of oil give off sulfurous fumes. This gas mixes with groundwater and forms HSO (sulfuric acid). The acid then dissolves the limestone from below, rather than from above, by acidic water percolating from the surface. Caves formed at the same time as the surrounding rock are called primary caves. Lava tubes are formed through volcanic activity and are the most common primary caves. As lava flows downhill, its surface cools and solidifies. Hot liquid lava continues to flow under that crust, and if