This geological process results in unusual surface and subsurface features ranging from sinkholes, vertical shafts, disappearing streams, and springs, to complex underground drainage systems and caves. The most famous of these features are caves. A speleothem is a technical term for any of the formations found in caves such as stalagmites, stalactites, columns, cave pearls, and so forth. Although caves are commonly associated with limestone and karst, not all caves are formed this way.
Some famous caves are lava tubes.
A lava tube is an underground conduit for magma that later drains and becomes an underground tunnel. Caves can be formed by other geological processes which you can find in some of the links listed below. Stalagmite - Points up. Resources on caves are in two other place in Nearctica . A segment of this site is a slide show of pictures and information on the caves of Indiana.