Caves In Spain

The portions of a solutional cave that are below the water table or the local level of the groundwater will be flooded.
The world's most spectacularly decorated cave is generally regarded to be Lechuguilla Cave in New Mexico. Lechuguilla and nearby Carlsbad Cavern are now believed to be examples of another type of solutional cave. They were formed by H2S (hydrogen sulfide) gas rising from below, where reservoirs of oil give off sulfurous fumes. This gas mixes with ground water and forms H2SO4 (sulfuric acid). The acid then dissolves the limestone from below, rather than from above, by acidic water percolating from the surface.
• Primary cave
Some caves are formed at the same time as the surrounding rock. These are sometimes called primary caves.