The Glass Mountains or Gloss Hills are a series of mesas and buttes that extend from the Permian red beds of the Blaine Escarpment of northwestern Oklahoma in Major County. The mountains rise 150 feet (46 m) to 200 feet (61 m) above the surface of the plains. The highest elevation in the formation is about 1,600 feet (490 m) above sea level. The Glass Mountains stretch west along US Highway 412 from Orienta south of the Cimarron River. The name comes from the sparkling selenite crystals on the slopes and tops of the mesas.