J.R.R. Tolkien > The Silmarillion >

Before the Eldar came, the Vala Aulë with the aid of Yavanna created two great lamps that would light all of Middle-Earth. They were filled with light by Varda and blessed by Manwë, then raised on high pillars, much taller than any of the mountains of later days. One was located in the north of Middle-Earth and was named Illuin, and the other in the south was named Ormal, and these two lamps lit all of Middle-Earth in an eternal spring.

Now, while the Valar rested from their work, Morgoth, or Melkor as he was then known, came and built a secret fortress beneath the earth, known as Utumno, and suddenly he attacked and destroyed the Lamps of the Valar. With the destruction of the Lamps whole lands were broken and seas boiled, and destroying flame ruined what was left, and the shape of Arda was forever changed, so that the original beauty of the lands as envisioned by the Valar was never after restored. The fall of Illuin created the inland sea of Helcar. Melkor escaped in the confusion, as the Valar had to use all of their power to restrain the tumults of the earth, and save from destruction what they could. Their original dwelling at Almaren was destroyed by those events, so they took refuge in the land of Aman, where they remained ever after. The world remained dark except for the stars of Varda, until the creation of the Two Trees of Valinor.