The Seal of the Earth is held by three runestones, held in the Pillars of Diamond, Opal, and Amethyst in Lethlor Ravine. Using the Sign of the Earth, you will be able to remove the runestones and unlock the Seal of the Earth.$b$bBe wary though, $n, the black drakes Blacklash and Hematus are not to be trifled with. See them dead and return their bindings to me.$B$BTo reach the ravine, travel to the far eastern part of the Badlands.  Be careful though, for the ravine is home to countless drakes.