We were digging out a cave and doing a right good job of it. At one point in the large room (for that particular cave) there were some slabs stacked and leaning against one wall. Now they would've NEVER probably moved at all if left well enough alone.
Alas one of the diggers said that he was feeling some great air coming out of where he was digging... the fella behind him got a bit over zealous and sadly careless, he started tossing the rocks handed to him where-ever... the room was formationless, and several of them hit those slabs... pretty soon there was an ominous crunching sound of rock sliding on rock... needless to say all of us got out of there in a big hurry.
Came back couple weeks later and shore enuff... those immovable slabs if left well enough alone slid and slided to a nice pile... right where we were diggin.
Turns out it was a convection air-movement and we found the source on the opposite side of that room... now we're blocked by solid rock above and below and all around... the hole where the air is a blowing (hard) is about the size of one's head... SIGH...
anyone spare a couple of "cave expanders??"