'Rock' in the Bible

For when Jezebel was cutting off the prophets of the Lord, Obadiah took a hundred of them, and kept them secretly in a hole in the rock, fifty at a time, and gave them bread and water.)

Has my lord not had word of what I did when Jezebel was putting the Lord's prophets to death? how I kept a hundred of them in a secret hole in the rock, fifty at a time, and gave them bread and water?

And there he went into a hole in the rock for the night; then the word of the Lord came to him, saying, What are you doing here, Elijah?