Traprock mountain

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Traprock (or basalt) mountains, ridges, (or just traps) are elevated landscape features made of trap rock, most often basalt. Basalt, due to its high quantity of iron, is a characteristically dark-colored rock that weathers to shades of red and purplish-red when exposed to the air. Basalt is the substance of many elevated topographic features worldwide (hills, mountains, ridges, rock formations, etc.). Landscape features composed of basalt may include:

  • Elevated sections of prehistoric ocean floor that have been raised above sea level via plate tectonics
  • Prehistoric terrestrial lava floods that have become upended and/or exposed via faulting and erosion
  • Various surface volcanic landforms both recent and ancient.

Because basalt has a tendency to fracture at abrupt angles, topographic features made of basalt often have a "postpile" appearance. Basalt ridges make up hundreds of square miles of topographic features in the northwestern United States, from Wyoming to Oregon.

Notable landforms[edit]

Prominent basalt ridges, mountains, buttes, canyons, and other landscape features include:

In the United States[edit]

Other parts of the world[edit]