Malpais

Malpais, found in the southwestern United States, Spain, Mexico and other Spanish-speaking regions, is a rough and barren landscape consisting of a relict, largely uneroded lava field that still exhibits recognizable lava flows, volcanic cones and other volcanic landforms. This kind of terrain is extremely rough and difficult to traverse, and is characteristic of arid environments, since in more humid climates such rugged surfaces are smoothed by erosion and vegetation.