A gigantic map of all the cool plaques in the world. A project of 99% Invisible. Logo by Chop Shop

Lake Peignuer

More than 140 years ago, Lake Peigneur was described as the most beautiful lake in the South. The present-day lake and adjacent Jefferson Island are located on an ancient salt dome that was the site of an unusual disaster. <p>

Like other salt domes in Louisiana, the Jefferson Island dome is made of salt deposited more than 165 million years ago during the mid-Jurassic period. When what would eventually become the continents of North America and South America began drifting apart, seawater evaporated in basins. The salt that formed here was eventually buried miles below the surface by more recent sediment from the Mississippi River’s various courses and distributary streams—a process which continues today. The weight of this younger sediment pushed up a column of salt, resulting in a landform referred to as an “island” because of its height relative to the neighboring land. Jefferson Island rises about 50 feet above the surrounding landscape and is the northernmost salt dome in the Five Island Trend—which includes Avery Island, Weeks Island, Côte Blanche Island and Belle Isle. Salt was mined here throughout the 1900s, creating a gigantic cavern below Lake Peigneur.<p>

This salt dome and mine intersected with the lake’s story just a few decades ago. It is said that on Nov. 20, 1980, an oil drilling company doing exploratory drilling in the area accidentally pierced the bottom of Lake Peigneur, creating a funnel for the lake to drain into the massive salt mine. Within hours an enormous whirlpool formed on the surface as gravity pulled Lake Peigneur into the cavern below, dragging a drilling rig, several barges, boats, a newly constructed house and 65 acres of land (including a lush botanical preserve) with it. The whirlpool’s suction was so intense that it eventually caused the Delcalmbre Canal—which normally flows away from Lake Peigneur and into the Gulf of Mexico—to reverse direction, forming a 150-foot temporary waterfall. It took two days for water from the canal to refill the almost empty lakebed. Once the water pressure equalized, nine of the lost barges were coughed up from the bottom of the lake. Miraculously, no lives were lost that day in the mine, but the damage to the island took several years to rebuild, and what was once a 10-foot deep freshwater fishing hole is—to this day—deep, brackish water. The cause of the disaster was never officially determined, but a lone chimney still rises above the water as a reminder of the catastrophic impact it had on this area.

<p>Today, visitors can learn more about Jefferson Island and its intriguing history at Rip Van Winkle Gardens, made up of the Joseph Jefferson home and surrounding gardens.

Nearby Plaques On Google Maps