'Clefts' in the Bible

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.

And they shall come, and shall rest all of them in the desolate valleys, and in the clefts of the rocks, and upon all thorn-hedges, and upon all pastures.

ye that inflame yourselves among the oaks, under every green tree; that slay the children in the valleys, under the clefts of the rocks?