Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 31 Number 4: 83-96- October 1969
A publication of the National Speleological Society
Processes of Cavern Breakdown
Elizabeth L. White and WIlliam B. White
Breakdown occurrences have been studied extensively in the large cavern systems of the Central Kentucky Karst and in caves elsewhere in folded limestones. Rosettes of straight breakdown block edges show strong preferred orientation suggesting that fracturing occurs along pre-existing zones of weakness. Wide-span ceilings have a measurable sag.
Some processes activating cavern breakdown are: (1) loss of buoyant support by draining of galleries (2) undercutting of banks by floodwater stopping at the base level (3) removal of support by free surface stream action (4) crystal wedging and attack by sulfate mineralization (5) frost wedging (6) undercutting by later cavern development (7) undercutting and removal of material by vertical shafts and shaft drains (8) weakening of ceiling beds through attack by acid surface water.
One or more of the mechanisms of cavern breakdown are operative during all stages of development. Thus breakdown takes place continuously and plays an important role both in the initial enlargement of the cavern system and in its final degradation.
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