Zalshir Crevasse

According to Celedor MacGarren:

• The Keep of Hashir, was once a great fortress owned by an emperor of what was then known as The Golden Basin. At some point, Hashir asked his grand sorceror Zalshir to conduct his research outside the keep, as he was toying with dangerous forces. Zalshir relocated his research 200 miles out into the dusty plains.
• At some point, a cataclysm struck Zalshir's underground laboratory, an explosion that rocked the world to its foundation and blotted out the sun for years. In the laboratory's place is now a 200-mile long chasm in the earth, called Zalshir's Crevasse.
• The Golden Basin became barren in the following decades, and renamed the Endless Waste. And the great inland sea eventually renamed, The Sea of Death, for it supports no normal water creatures. As the land and waters were so blighted, the keep was abandoned.

From a character's vision upon touching one of the Luma Stones:

Finally, you become aware of how the stones may be destroyed: by returning them to the site of their creation and hurling them into a great breach in the flesh of the planet.

Your mind races back in time to a scene millenia ago, a scene of a robed magi, insane with power, laboring to create a huge red orb. Then, an explosion that rocks the earth to its core, creating a crevasse 10 miles deep, 10 miles across, and over a hundred miles long. The debris, smoke, and dust from the explosion darkens the sky for a thousand miles.

Your vision of the crevasse in the midst of a darkened plain retreats quickly towards the crimson setting sun, eventually passing over a huge black stone structure and a shallow inland sea, before your conscious mind fades back into reality.

Location: Map 8