Traprock mountain

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