Underwater forest? 'Enchanted forest' provides tantalizing hints to past climate.
Underwater forest: An underwater forest discovered in the Gulf of Mexico contains trees that lived for hundreds or maybe thousands of years, and died over 50,000 years ago.
Sixty feet underwater, ten miles from shore, divers discovered an underwater forest of cypress trees that had been buried for tens of thousands of years.Skip to next paragraph
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While most of the once-majestic trees are gone, sonar data has found between 50 and 100 stumps, as well as an unknown number of logs. The trees are closely related to the modern-day Bald Cypress, says Grant Harley, a tree ring expert at the University of Southern Mississippi. "The growth rings look just like the Bald Cypress growth rings I've looked at hundreds of times," he says.
And there were a lot of growth rings, so close together that Dr. Harley had to use a high-powered microscope to count them. In a sample the size of a coffee cup, he says, he found 424 years of growth rings. Considering that the larger tree stumps were upwards of six feet in diameter, these trees could easily be thousands of years old. "That's much, much older than Bald Cypress growing today," Harley notes. "It's more comparable to redwoods."
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The forest itself has been dead at least 50,000 years, say scientists at the Lawrence Livermore Laboratory in California who dated samples from the trees by looking for carbon-14, a radioactive isotope that is found in every living organism but that steadily decays after the organism dies. The scientists had expected to find that the trees were about 12,000 years old – the age of the last big ice age, when sea levels were low – so they were surprised to find that the trees had no carbon-14 at all, which puts them older than 50,000 years.
Another surprise: the wood still seemed fresh. Ben Raines, one of the first scuba divers to explore the site, tweeted a picture showing the sap-rich wood.
“It is a little darker in color than a piece of modern cypress, but if I didn’t tell you that it was over 50,000 years old, you wouldn’t know it,” paleoclimatologist Kristina DeLong, the Louisiana State University research scientist who prepared the samples for carbon dating, told AL.com. “When I cut into them, they smelled just like you were cutting into a cypress tree.”
As he explored the site, Mr. Raines noticed that the outer edges of the trees are becoming softened and pockmarked – what Harley describes as "punky and friable" – but the inner wood is still hard enough to blunt a knife.
To be so well preserved, the forest must have been completely buried by seafloor sediments, say geologists. A thick enough layer of mud or clay could create an airtight seal that prevented decomposition, until hurricane Katrina's churning waves washed the trees bare.
“It certainly makes sense that these were preserved under anaerobic conditions,” Berry H. "Nick" Tew, the state geologist of Alabama, told Raines.
Harley agrees. "Now that they're in an aerobic environment," he warns, "I don't think we have too much longer." He estimates the forest has only a few years before the trees completely decompose. "Oxygen's attacking it, marine boring organisms are attacking it."
How the underwater forest was discovered
As the story goes, a fisherman went out to sea shortly after hurricane Katrina scoured the Gulf Coast. He found an unusual run of red snapper, and after fishing it for several days, he asked a scuba-diving friend to check out what could be causing the usually flat and boring sea floor to teem with life. "It's a forest," the diver reported. Dozens of cypress trees and stumps, reaching as far as he could explore.