§ Of the Sun and Moon and the Hiding of Valinor The Silmarillion

Therefore by the coming and going of Anar the Valar reckoned the days thereafter until the Change of the World. For Tilion tamed seldom in Valinor, but more often would pass swiftly over the western land, over Avathar, or Araman, or Valinor, and plunge in the chasm beyond the Outer Sea, pursuing his way alone amid the grots and caverns at the roots of Arda. There he would often wander long, and late would return.