No injured cavers recorded.
On September 10, Jim Borden, Don Coons and Mark Stock entered Morrison's Cave in Barren County, Kentucky. They proceeded to a 30 foot drop with a dome over it. Borden down-climbed the pit via a narrow canyon while Coons and Stock ascended the very steep, unstable, mud and rock wall to look for leads at the top of the dome. About 40 feet up they reached the top where a crawlway led off.
This needed digging out so they yelled to Borden to beware. Then Coons began to dig with Stock behind him, bridging the dome at the ceiling. The digging apparently caused vibrations and small rocks began to fall out of the ceiling around Stock's head. As Coons wriggled into the crawl, Stock took notice of a 1x2x1 foot rock above him with nothing to support it. As he moved to one side, it and much debris around it, plummeted into the pit, knocking the lamp off Stock's helmet. At the same time another rock 4.5x3x1 feet slipped down onto Stock's shoulder and smaller rocks fell all around him.
Coons, in the crawl, gave Stock some light. Stock then grabbed Coons' foot and made a desperate lunge into the crawl. The boulder, as it and material around it groaned and fell, missed him by only a foot. The two then watched as "the unstable ceiling would gasp and moan in a most grotesque manner as the rocks and mud would settle downward then massive avalanches would thunder into the void".
When the ceiling had retreated upward for some 15 feet in this manner it seemed to stabilize and thrown rocks had no effect. The two quickly retreated and, with Borden, who had sat it out in an alcove, left the cave.
Rockfall is especially dangerous in unexplored caves, perhaps, but can occur anywhere. Instabilities can often be seen. At any rate, don't think it can't happen!