DevilsPostpileNational Monument's landscape is a reflection of fire and ice. The eruption and uniform cooling of basalt lava created an impressive wall of columns. Later a glacial event exposed the columns and polished smooth the top of this formation enhancing the pattern of hexagons that are a result of the mineral composition of the lava. Located on the western slope of the Sierra Nevada range at 7,200 to 8,200 feet (2,200 to 2,500 meters), the 798 acres (320 hectares) is a small but rich environment.