Charles Ellicott Commentary Isaiah 2:21

"to go into the caverns of the rocks, and into the clefts of the ragged rocks, from before the terror of Jehovah, and from the glory of his majesty, when he ariseth to shake mightily the earth." — Isaiah 2:21 (ASV)

To go into the clefts of the rocks... — Compare Exodus 33:22 for the phrase. The picture of Isaiah 2:19 is reproduced, with some noticeable variations. As they feel shock after shock of the earthquake, see the flashing fires, and hear the crash of the thunder, they leave the larger caverns where they had at first sought shelter and where they have left the idols that were once so precious, and fly to the smaller and higher openings, the clefts of the rocks, and the rents of the crags, in their unspeakable panic.