From Halopedia, the Halo wiki
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. The escarpment began in the northern plains, south of the Hugin Sea. The Bifrost was composed of limestone shale. The Bifrost was also connected to the Plains of Ida and was close to Harvest's capital city, Utgard. The Mimir River ended at the Bifrost, forming a waterfall that turned into the Slidr River at the bottom of the escarpment. The Slidr River followed the contours of the escarpment until it drained at the Munin Sea. The gardens of the Harvest Botanical Gardens stepped down from the Bifrost in three landscaped tiers, the lowest of which was a broad lawn of close-cropped grass.
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