The hills melted like wax at the presence of the Lord - They seemed to flow down as if they were like melted wax: that is, they could not stand before him. The most firm, solid, lofty things were as nothing in his presence. Compare Revelation 20:11; Judges 5:5; Micah 1:4; Nahum 1:5. The object here is to describe the sublimity, the greatness, the majesty of God, as if nothing could stand before him; as if everything fled away when he approached. There is perhaps a general allusion to his glory and power as manifested at Sinai.
At the presence of the Lord of the whole earth - The Creator and Ruler of the entire world. The God who thus manifested himself is not a local Deity, or the God of a particular nation or country, but the God of the whole world, before whom all created things are as nothing.