Glossary of Karst and Cave Terms
1. The collapse of the ceiling or side walls of a cave or of the land surface into a subterranean passage as a result of undermining or of pressure from above . 2. The partial or complete collapse of earth material into a large underground opening, such as an excavation or a mine. 3. The sudden slumping of wall material into a pit. 4. A place where material has collapsed or fallen in or down.