More than 500 salt domes have been discovered along the Gulf Coast, from Texas to the Florida panhandle.
They are mostly made of pure salt, or halite, and were formed over millions of years from thick beds of salt several miles below the Earth’s surface.
Because the salt walls will not allow fluid or gas to escape, some of the domes are ideal for storing petroleum products such as propane, butane, ethane, and methane.
The U.S. government stores an emergency supply of crude oil in more than 50 of these salt domes along the Texas and Louisiana coast.
It is called the Strategic Petroleum Reserve, and with a capacity of 700 million gallons (2.6 trillion 1) is the largest emergency stockpile in the world.
A typical salt dome cavern is 200 feet (61 m) in diameter, 2,000 feet (610 m) high, tall enough for Chicago’s Sears Tower to fit inside with room to spare, and can hold up to 10 million barrels of oil.
An ample source of fresh water and sediment, the Mississippi shaped much of the coastline of Louisiana.
Today, the effects of human and natural forces on the river’s course place the coastal wetlands at risk.