cave
cave
Fragmented rock materials, derived from the sidewalls of a borehole, that obstruct the hole or hinder drilling progress.
o allow a mine roof to fall without retarding supports or waste packs.
A falling in of the roof strata, sometimes extending to the surface and causing a depression therein. Also called cave-in.
The partial or complete failure of borehole sidewalls or mine workings
Collapse of an unstable bank
A natural cavity, recess, chamber, or series of chambers and galleries beneath the surface of the Earth, within a mountain, a ledge or rocks, etc.; sometimes a similar cavity artificially excavated.
Time in Riyadh 
at any time
