From Halopedia, the Halo wiki
The Highland Mountains, or informally the 'Highlands' are a large range of alpine mountains located within the Viery Territory of the human colony, and UNSC fortress world Reach. Located on Reach's northernmost continent Eposz, the mountain range stretches many hundreds of kilometers, comprising thousands or tens of thousands of individual peaks. The Highland Mountains are mostly granite. Due to the area's remoteness, it was home to many UNSC facilities before the planet's glassing in 2552.
After the Fall of Reach on August 30, 2552, The Highlands were one of the few areas on Reach to escape the Covenant plasma bombardment, though glassing did occur in the area on a small scale. The Covenant concentrated their forces in the region and set up an extensive excavation operation around Menachite Mountain in order to uncover a massive subterranean Forerunner structure.
The Highland Mountains experienced widespread ecological disaster in the wake of much of the planet's glassing. Firestorms from the surrounding plains spread up into the Highlands, burning entire forests and melting through rock. Months of black rain had followed, washing the mountainsides bare, and causing landslides the size of cities to wash down into the lower valleys.
By 2559, areas that had once been snow-covered slopes had been replaced by banks of seared dirt and charred stone. Entire meadows still lay blanketed in cinders and ash. Forested areas had been replaced by bare stony wastelands, and valleys were filled in by kilometers-deep bogs of mud and ash. Small areas on the lower slopes however, showed signs of recovery, with foliage beginning to regenerate between the massive scars left by landslides.
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