This and the two next verses are meant either,
1. Of other eminent and considerable works of God, who sometimes overturneth rocks, and produceth new rivers in unlikely places. Or rather,
2. Of the same work of mining and digging for gold, or other precious things of the earth, and of other effects of man's art and wisdom in that work. The miners resolve to break through all opposition, and by iron tools, or fire, or other ways, dig through the hardest rocks. He undermineth the very mountains to find out the metals lying at the bottom of them.