Many slot canyons are formed in sandstone and limestone rock, although slot canyons in other rock types such as granite and basalt are possible.
Some slot canyons can measure less than 1 metre (3 ft) across at the top but drop more than 30 metres (100 ft) to the floor of the canyon. Slot canyons are subject to flash flooding and commonly contain unique ecological communities that are distinct from the adjacent, drier uplands. The term is especially used in the semiarid southwestern United States and particularly the Colorado Plateau. A slot canyon has depth-to-width ratios that typically exceed 10:1 over most of its length and can approach 100:1. A slot canyon is a long, narrow, deep and tortuous channel or drainageway with sheer rock walls that are typically eroded into either sandstone or other sedimentary rock.
