Formation of Domes
Millions of years ago, the earth was covered by salty oceans and inland seas. When water receded and evaporated, fields of salt remained. The abundance of salt domes in Louisiana and other southern states are a result of the fluctuations of the Gulf of Mexico over thousands of years. These salt fields were covered year after year by rocks and sediment. Salt, being a crystal, is lighter and more buoyant than the heavy rocks above it. Due to this, salt will move upwards, breaking through weakest geographic layers above them. Salt behaves somewhat fluidly underground, pooling together in to huge ‘domes’ which push upwards. As they near the surface, these domes push up the rocks above them creating hills. The “five islands” (Jefferson Island, Avery Island, Weeks Island, Cote Blanche and Belle Isle) in South Louisiana were all created by salt domes. Red River flows over an underground salt dome near the Texas-Oklahoma border, causing it’s high salt content. Domes can be one to five miles across and reach as deep as 10,000 feet.
