Perhaps the building of Illuin caused a depression to be made in the land, resulting in the crater-like formation of Mordor. The land beneath the "tower" could have sunk, while the land around it could have stayed at the same level. In order to throw it down, Morgoth could have raised up Mt. Doom, and caused a massive eruption, which would have severely weakened the foundations of the pillar.
__________________
But Melkor also was there, and he came to the house of Fëanor, and there he slew Finwë King of the Noldor before his doors, and spilled the first blood in the Blessed Realm; for Finwë alone had not fled from the horror of the Dark.
|