Underwater archaeology

Jessi Halligan operates an underwater vacuum that sucks up sediments and artifacts to be screened on the surface. Credit: Center for the Study of the First Americans  Jessi Halligan operates an underwater vacuum that sucks up sediments and artifacts to be screened on the surface. Credit: Center for the Study of the First Americans
As the ice sheets melted at the end of the last ice age, sea level rose dramatically, drowning much of the paleo coastline of North and South America under meters of water. To find evidence old enough to be associated with the initial colonizers, archaeologists have to get wet, even donning scuba gear to search for human relics along the Gulf and Atlantic coasts. Such work is highly technical and expensive, but a small handful of divers trained in underwater archaeological excavation techniques insist that it’s worth the trouble. 

“Underwater archaeology is much more complex and costly than traditional terrestrial archaeology, but it excels at answering the kinds of questions we really want to know,” says Jessi Halligan, an underwater archaeologist at Florida State University whose team discovered 14,450-year-old butchered mammoth bones and stone tools at the Page-Ladson site, a sinkhole at the bottom of the Aucilla River, south of Tallahassee, Fla., last year. Halligan’s team was able to glean more than 70 radiocarbon samples for dating from well-preserved mammoth dung found surrounding the artifacts — helping to quell any doubts about the age of the site. 
Water can actually protect a site because it creates an environment that preserves the organic materials that are necessary for accurate radiocarbon dating, Halligan says. At many terrestrial Paleoindian sites, researchers are lucky if they get even one reliable radiocarbon date, she says. With the controversy that often surrounds the announcements of older sites, multiple radiocarbon samples are necessary to fend off criticism. 
Despite the benefits of underwater preservation, “underwater archaeology is never going to be mainstream because of the 
funding required and the logistics of spending time underwater,” she says. Halligan estimates there are a few hundred people in the world with the unique skill set to work as underwater archaeologists, but most specialize in shipwrecks. “Fewer than a dozen people are focused on paleosites that have been inundated by sea-level rise,” she says. 

Mary Caperton Morton

Mary Caperton Morton

Morton (https://theblondecoyote.com/) is a freelance science and travel writer based in Big Sky, Mont., and an EARTH roving correspondent.  

Sunday, January 1, 2017 - 06:00

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