The Massive Log Jam That WasPosted: March 2, 2012
It filled the river in both directions as far as the eye could see and continued on for many miles. It was called the Great Raft, and it lived in the Red River, which lines the Texas-Oklahoma border and ends at the Mississippi River in Louisiana. It was an unusual sight: an enormous log jam that, depending on the account, stretched anywhere from 100 to 210 miles long. It’s also the kind of thing you don’t see in the North American wilderness any more.
It’s unknown how old it was, but it was almost certainly caused by the natural migration of the river. Rivers are not the motionless, changeless squiggly lines that you see on maps. They shift across their floodplains, gradually, like a giant worm that takes millennia to squirm. Often, they even sever some of their curves and bends, leaving behind small lakes that look like a loop snipped off a length of ribbon. The Great Raft probably developed slowly as the river undercut its shoreline forestland, and the trees toppled in and accumulated.
In the 1830s, the federal government decided to open the Red River up for travel and commerce. It took them five years to remove the raft using steamboats and manual labor. But nature was stubborn — soon after they were done the raft began to regenerate, and within years it extended for miles all over again. The second removal attempt was interrupted by the Civil War and its surrounding political turmoil. The U.S. Army Corps of Engineers returned to the project in the 1870s using crane boats and explosives, until it was finally completely cleared away in 1873.
Though a log jam may look like just a messy obstruction — piles of rotting wood laying in dirty water — dead trees can have an impact on the environment just as living ones do. Robert Gastaldo, a geologist at Colby College in Maine, studies the evolution of terrestrial plants and the ecology of eras long passed. He has also used historical records about The Great Raft as a basis for comparison for his research on log jams from millions of years ago. His best guess is that the Great Raft would not have been an impediment to the flow of water in the same way it was an impediment to human travel. The raft’s removal would have slowed the river down because, without the squeeze from the logs, the water could move at a slower speed and still deposit its water at about the same rate.
The removal of the logs would likely have caused problems for fish that stay near the woody covering for protection. Records also show some small trees took root on the decaying wood. As the wood rotted it became like any other organic soil, Gastaldo says, and if a seed landed there it would have taken root, resulting in little trees growing on the floating remains of bigger trees. “It would’ve changed the ecology for sure,” says Gastaldo of the raft’s removal. “But who’s to say it was for the better or for the worse?”
Any sign of the raft is long gone now. To the 19th century Army Corps of Engineers, the raft was just a roadblock that had to be removed. The landscape was deforested for agriculture after the Civil War, and much of the earth that had gathered under the raft was moved downriver into the Mississippi. Though Gastaldo notes that modern-day engineers know that log jams would impact the river flow and would take the overall impact into account.
Some links if you want to read more:
- Further history with more details on efforts to remove the raft
- Gastaldo’s 2007 study using the Great Raft as an analog for an ancient log jam
- Photograph part of the public record of the State Library of Louisiana