Tag: Lake Peigneur

Bayou Corne Sinkhole: A Growing Enviornmental Disaster in Louisiana

Submitted by Charlton Stanley (aka Otteray Scribe), Guest Blogger

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Salt Dome Illustration by the Louisiana Department of Natural Resources

There are gigantic salt deposits under the state of Louisiana. Geologists tell us the salt dome under Assumption Parish is about the same size as Mt. Everest. Some of the deposits are as deep as 35,000 feet as shown in this not-to-scale drawing. In fact, huge salt deposits are under large patches of the North American continent along the Mississippi River valley all the way up to Lake Erie. The city of Cleveland is sitting on top of a large salt deposit.

Salt settled out of the water when these areas were part of the ocean as the continent of North America was forming. We have all seen what happens if you dissolve salt in water. It reaches a saturation point, where no more salt can be dissolved. At that point, the excess salt settles to the bottom. That process is still going on at the surface in places like the Great Salt Lake and the Dead Sea. Once the water evaporates, it leaves behind places like the famed Bonneville Salt Flats. The excess salt in the water in those formative years of this continent settled out into enormous deposits. The primary deposits of salt are deep underground, as far as ten thousand feet or more. However, like glacier ice, solid crystal salt becomes somewhat plastic under great pressure. At ten thousand feet, the overburden of rock and sediment creates pressures of thousands of pounds per square inch. Salt deposits find weak places in the rock, and start squeezing upward in plumes, called “salt domes.” These extrusions come nearer the surface, making the salt more accessible so it can be mined. When I lived in Louisiana as a kid, I remember the salt mines being an everyday topic of conversation. The salt is not only used for food, but has many industrial uses as well. During World War Two, the salt mines provided essential minerals used in the manufacture of ammunition and high explosives. Salt mining in Louisiana has been going on since before the Civil War. Some of the mine shafts go down as much as ten thousand feet, and some of the salt caverns that have been mined are enormous.

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