Badlands are a particular type of rock formation found in arid regions around the world. These formations require poorly consolidated rock and infrequent but torrential rain. The soft rock allows large quantities of water to channel down gullies, carrying away sediment. Bentonite clay within these formations can swell up with moisture. As the clay dries it shrinks and cracks, creating a surface resembling the skin of an elephant. Beneath the surface, an intricate maze of natural pipes and spaces form within the badlands. This hidden plumbing appears on the face of the badlands as dimples, sinks, slumps and seeps. As erosion continues, new features including caves and natural bridges can form. Badlands often take on varied colors giving the formations a banded appearance. These colorful badland formations were at Blue Mesa in Petrified Forest National Park near Holbrook, Arizona, USA.