by Winding through the low country of South Carolina, the Cooper River is a reedy haven for sportfish and shorebirds. The waterway originates from Lake Moultrie in Berkeley County. From there, it goes all the way down to Charleston, where it joins the Ashley and the Wando to create a world-famous harbor in that city. (Have you ever heard of Fort Sumter?)
The Cooper River got its name from Anthony Ashley Cooper, an English lord from the 17th century. As time went on, he retired from the growing rice trade of the region. But the Cooper also bears the hallmarks of a much older chapter in South Carolina history.
If you know where to look, and have scuba gear handy, you may find a giant stingray lurking beneath the water’s surface.
Matthew Weas knows that feeling. He and his father, Joe Harvey, are experienced local divers who patrol the Cooper for fossils – many of which are on display at the Berkeley County Museum in Moncks Corner, South Carolina.
Not all the giants they encounter are prehistoric. To hear Weas tell it, run-ins with alive modern day river beasts are not uncommon. “There was a [catfish] My hand is swallowed in a hollow underwater jam, a manatee breaks the surface as I swim back to the boat… [and] alligator swimming towards me,” he says via email. Once, he came “nose-to-nose” with a gator measuring about 10 feet (3 meters) long.
Cave of Wonders
The American alligator may be synonymous with the South, but underwater fossil hunting is a global pastime. Outside of the United States, divers have found paleo-treasures in places like Australia, Bali, Brazil, Indonesia, Mexico and the Bahamas.
Back in 2014, a bona fide “lemur graveyard” was discovered in the submerged caves of Madagascar’s Tsimanampetsotsa National Park. The major discovery was made thanks to a joint international effort between anthropologists, paleontologists and scuba divers.
Hundreds of bones were visible in the underwater sediments. Some came from contemporary species such as the invasive black rat. Other remains were left behind by animals that went extinct in the last few thousand years.
The site quickly established itself as the world’s largest cache of it Pachylemur fossils. An ancient relative of the ruffed lemur, this creature was about twice as heavy, weighing an estimated 22 pounds (10 kilograms). It would be completely dwarfed by the gorilla-sized Mesopropithecusgargantuan lemur also represented in the caves.
The dive team also recovered a pygmy hippopotamus, an elephant bird and a horned crocodile — along with the rare, nearly complete skull of another extinct species of lemur.
Accessing the bounty was not easy. The caves in question were probably once dry, but today they are part of a submerged sinkhole. Currently, the largest fossil cave in the system is 82 feet (25 meters) deep. It’s a dark environment with a complex layout, full of horizontal passages and murky waters.
In short, this is no place for novice divers. Cave diving is generally a high-risk sport; if you wander, you can’t always rise to the surface. So to avoid getting lost, the scuba specialists on that 2014 team charted their paths with about 879 feet (268 meters) of safety lines.
Preparation is Key
Another valuable sink is the Page-Ladson site in northwest Florida. Hidden beneath the Aucilla River, some of the oldest known human artifacts in North America have been discovered. Equally interesting are the mastodon bones of the area, including some 14,550-year-old fossils with scars that suggest the animals were butchered by ancient Floridians.
Here, tannins are a real nuisance. A vital component in leather, tannins are chemical compounds released by various plants. When these flow into ponds or rivers, they can turn the water brown. Needless to say, this affects visibility. In some corners of the Aucilla, the tannins help block sunlight, shrouding everything deeper than 10 feet (3 meters) below the surface in pitch black.
Back north in the Cooper River, divers have the same problem. To see clearly, they – and their colleagues based in Aucilla – make good use of high-wattage underwater lights.
Weas says he and his father wear Dive-Rite “cave lights” attached to their helmets. The rest of the duo’s gear would look very familiar to other recreational divers. “We use the standard tank, regulators and BCDs,” says Weas. (For the record, BCD stands for “Buoyancy Compensation Device,” a wearable gadget used to keep divers at a desired depth.)
On summer dives, Weas and Harvey can comfortably wear pants and T-shirts. But under some weather conditions, a dry suit, semi-dry suit or wet suit may be more appropriate. Since the Cooper receives strong tidal currents, the speed of the water at any given time affects its schedule. Faster currents make shorter trips.
Giant Sharks … And Beavers?!
Why do people go through all this trouble when there are so many fossils hanging on dry land? Well for one thing, immersion in water has some conservation benefits. Deep in the bowels of a drowned cave, bones are less likely to be disturbed – by scavengers or the ravages of outdoor climates.
And while terrestrial fossils are often caked in rock, some of the bones in flowing rivers are polished clean by the currents.
Most of the material Weas finds out in the Cooper River comes from two different points in geologic time. Probably the most popular fossils in the river are shark teeth from the Miocene Epoch, which lived between 23 million and 5.3 million years ago. Some of these compers get quite large: A tooth from the extinct megalodon shark can be up to 7.6 inches (19.3 centimeters) long!
“Shark teeth are the most common finds,” says Weas, “although whale ear bones [in] a close second.”
Other Cooper River fossils were deposited during the later Pleistocene. That started just 2.6 million years ago and ended just 11,700 years before today. Back then, sea levels were lower and the Carolina coast was farther east.
Over the years, Weas and Harvey have exhumed the bones of Pleistocene mammoths, capybaras, hoofed herbivores — and giant beavers. The latter asks for an explanation. During the last ice age, the wetlands of North America were occupied by Castoroides8-foot (2.5-meter) Beavers that probably weigh 220 pounds (100 kilograms) or more.
A manatee sneaking up on you is definitely scary. But imagine swimming with one of those giant rodents! Thanks, but no thanks.
Now That’s Interesting
Great Britain was connected to the rest of mainland Europe as recently as 8,200 years ago. For this reason, huge bones are periodically dredged out of the North Sea, which separates the UK from its continental neighbours.
Source: Riverbed Bones: The Curious World of Underwater Fossil Hunting
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