Salt domes are located in the Zagros Mountains, in southwestern Iran. Thick layers of minerals such as halite (common table salt) typically accumulate in closed basins during alternating wet and dry climatic conditions. Over geologic time, these layers of salt are buried under younger layers of rock. The pressure from overlying rock layers causes the lower-density salt to flow upwards. Salt rocks with orange, yellow, red and gray lines, which indicates the existence of metal elements, are also called Rainbow Salt.