Near Gulf Shores, Alabama, LSU researchers have been studying “underwater forests,” a rare phenomenon in which natural circumstances have preserved trees for tens of thousands of years underwater. These submerged troves of biodiversity have been a hot topic for geologists, anthropologists and other researchers for years. 

Kristine L. DeLong, a paleoclimatologist and LSU geography and anthropology professor, has been working on these sites since 2012. She said the last decade has been productive for her research. 

In archaeology, there are two kinds of remains: biological and non-biological. Biological remains can come from humans, plants and anything that will eventually decompose. Non-biological artifacts are the exact opposite. 

Because of decomposition, there is a common understanding that after a certain length of time, finding biological remains is impossible, as they would have already decomposed.

And yet trees that should’ve long since withered and broken down have been found sitting at the bottom of the Gulf of Mexico. Why?

DeLong said the researchers found that part of the reason the trees weren’t eroded away was the stillness of swamp water and its chemical composition. 

“When you walk in the mud [the swamp] has that smell; that’s the sulfer. So what’s happening is that there is no oxygen, and decomposition is not happening, and the wood is preserved,” DeLong said. 

DeLong first learned about the site years ago when she saw a local fishing shop’s post advertising a “swimming with dinosaurs” scuba experience. As a scuba diver herself, she was interested, and the shop had even posted a video of the trees lining the gulf floor online.  

The tree remains were originally found in 2004 by a fisherman after hurricane Ivan. The storm had disrupted the mud and sediment at the bottom of the gulf and uncovered the ancient stumps that had miraculously survived thousands of years. 

The trees are not just valuable as representations of the past to be studied. They also serve an ecological good, acting as a coral reef and giving animals and plants a home. 

“There are shrimps and crabs, all kinds of creatures that live at the site,” DeLong said.

DeLong said she was immediately invested in the site after her first visit. After collecting wood samples and sending them to the lab for radiocarbon dating, she estimated the trees to be around 10,000 years old. The results of the radiocarbon dating process would be even more impressive than she thought.

DeLong said 10,000 years would have been a big deal, as the stumps would’ve existed around the end of the Ice Age. 

“I was really excited thinking this site is going to be 10,000 years old. When the results came back, they said the site was is radiocarbon dead,” she said.

Being radiocarbon dead means the material in question is too old to date using that method. This meant the trees were over 50,000 years old, blowing even DeLong’s estimate out of the water.

“We have since done another dating method where we date the last time the sediments were exposed to sunlight, and we’re finding that the age when these trees were alive was between 60,000 to 70,000 years ago. For reference, 50,000 to 60,000 years ago is when humans began migrating out of Africa,” DeLong said. 

The discovery of trees from such a long time ago is incredibly rare, so it provides an exciting new kind of site for archaeologists and geologists to study.

“When we first started working on the site, I knew it was special,” DeLong said. “We knew the site was unique. Talking to other researchers and scientists, we haven’t been able to find any other sites like this.” 

DeLong mentioned other sites with preserved wood or biological remains, but she said this is the oldest one to ever be found in water. Over the past 12 years, DeLong and other researchers have spent a great amount of time and effort studying and publishing papers about this site. 

She said the researchers are almost done with their “phase one” of learning and that other sites are currently being found that resemble the original trees from 2004.

“I now have sites all the way from Mississippi to Florida,” DeLong said.

DeLong said the sites could have lasting impacts on the fields of Geology and Archeology as a whole. 

“One of the things marine archaeologists are concerned with is if there are any early humans,” she said. 

The Gulf Shores sites could help point researchers in the direction of other places that may contain early human artifacts, even if those places aren’t on land. 

DeLong also mentioned how attractive these sites are for young researchers who want to make important discoveries, citing some of the grad students working on the project.

“It’s not about grades. It’s about wanting to do discovery and asking questions, persevering and answering those questions,  doing the unknown, and not being afraid to do that,” she said.