Geerhardus Vos (in his Reformed Dogmatics, Vol.1) defines these as:

Immensity – That perfection of God whereby He is exalted above all distinction of space, yet at every point in space is present with all His being and as such is the cause of space.

Immutability – That perfection of God whereby He is exalted above all becoming and development, as well as above all diminution, and remains the same eternally.

And then, there is Psalm 46:1-3, “God is our refuge and strength, Avery present help in trouble, therefore, we will not fear though the earth gives way, though the mountains be removed into the heart of the sea, though its waters roar and foam, though the mountains tremble at its swelling.”