Largely subsurface geologic structure that consists of a vertical cylinder of salt embedded in horizontal or inclined strata. In the broadest sense, the term includes both the core of salt and the strata that surround and are domed by the core. Major accumulations of oil and natural gas are associated with salt domes in the U.S., Mexico, the North Sea, Germany, and Romania; domes along the Gulf Coast contain large quantities of sulfur. Salt domes are also major sources of salt and potash on the Gulf Coast and in Germany, and they have been used for underground storage of liquefied propane gas. Storage bottles, made by drilling into the salt and then forming a cavity by subsequent solution, have been considered as sites for disposal of radioactive wastes.