The term subsurface cavity
is used to denote all subsurface features cavities, caves, caverns,
voids, karst, and sinkhole. The most abundant natural
cavities are formed by dissolution processes in carbonates (e.g.,
limestone and dolomite) and evaporates (e.g., salt, gypsum, and
anhydrite). Karst refers to a characteristic topographic feature that
is developed by dissolution made by downward percolating
meteoric water