Bifrost

The Bifrost was an escarpment on the planet Harvest that cut southwesterly across the Edda supercontinent diagonally. It was stated by the AI Mack that the Bifrost was the only major change in elevation on Edda.

Trivia

 * The Bifröst is the rainbow-colored bridge connecting Asgard to the Human world of Alfheim, it is located after the Plain of Ida. This is yet another Norse Mythology allusion in Halo: Contact Harvest.