Winding through South Carolina’s low country, the Cooper River is a reed‑lined corridor that attracts sportfishers and shorebirds alike. Originating in Berkeley County’s Lake Moultrie, it travels south to Charleston, where it joins the Ashley and Wando rivers to form the world‑famed harbor that once cradled Fort Sumter.
Named after 17th‑century English statesman Anthony Ashley Cooper, the river once served as a vital artery for the region’s rice trade. Today it also hints at a much older chapter in South Carolina’s geological history.
With the right training and scuba gear, divers may uncover a mammoth tusk or other ancient remains lurking beneath the river’s surface.
Matthew Weas, along with his veteran father, diver Joe Harvey, patrol the Cooper for fossils. Their finds often find homes at the Berkeley County Museum in Moncks Corner.
Not all discoveries are prehistoric. Weas recounts encounters with contemporary river fauna, including a catfish that swallowed his hand in a log jam, a passing manatee, and an alligator that approached him. He recalls a close‑up with a ten‑foot (3‑meter) alligator.
This skull was from an extinct lemur that was part of a primate community in Madagascar that disappeared during the last 1,100 years. — Barry Coleman
While the American alligator is synonymous with the South, underwater fossil hunting spans the globe. Divers in Australia, Bali, Brazil, Indonesia, Mexico, and the Bahamas have unearthed priceless relics beneath the waves.
In 2014, a “lemur graveyard” was discovered in the submerged caves of Madagascar’s Tsimanampetsotsa National Park. The find was the result of an international collaboration between anthropologists, paleontologists and scuba divers.
Hundreds of bones appeared in the underwater sediments, ranging from contemporary species such as the invasive black rat to remains left behind by animals that vanished within the past few millennia.
The site quickly established itself as the world’s largest cache of Pachylemur fossils. This ancient relative of the ruffed lemur weighed an estimated 22 pounds (10 kg) and was dwarfed by the gorilla‑sized Mesopropithecus, a gigantic lemur also represented in these caves.
Other finds include pygmy hippo, elephant bird and horned crocodile material, as well as the rare, virtually complete skull of another extinct lemur species.
Accessing the bounty was not easy. The caves were likely dry at one point but are now part of a flooded sinkhole. The most fossil‑laden cave stretches 82 feet (25 m) deep and features a complex layout of horizontal passages and murky waters.
Because cave diving is inherently high‑risk, the 2014 team used about 879 feet (268 m) of safety lines to keep track of their routes and avoid getting lost.
This 30‑inch piece of mastodon tusk was recovered during a dive in the Cooper River in South Carolina. — Joe Harvey
The Page‑Ladson site in northwestern Florida, hidden beneath the Aucilla River, has yielded some of the oldest known human artifacts in North America. Equally fascinating are the locality’s mastodon bones, including 14,550‑year‑old fossils bearing scars that suggest they were butchered by ancient Floridians.
In the Aucilla, tannins released by plants seep into the water and darken it, turning it blackish‑brown. This chemical compound can reduce visibility dramatically, especially below 10 feet (3 m), where the water becomes an inky darkness.
Cooper River divers face the same challenge. To see clearly, they, along with their Aucilla‑based colleagues, use high‑wattage underwater lights.
Weas and Harvey equip themselves with Dive‑Rite “cave lights” mounted on their helmets. Their standard gear includes tanks, regulators and BCDs (buoyancy‑compensating devices). During summer dives they wear pants and T‑shirts, but in colder weather they opt for dry suits, semi‑dry suits or wetsuits. Strong tidal currents in the Cooper influence dive duration—faster currents shorten the time they can spend underwater.
This cache from a dive in the Cooper River includes several shark’s teeth as well as a brass Colonial belt buckle. — Joe Harvey
Why venture underwater when many fossils are on dry land? Water preserves bones by shielding them from scavengers and weather. In flowing rivers, currents can even polish the remains, leaving them remarkably clean.
Most of the material Weas discovers in the Cooper comes from two geological periods. The river’s prized fossils are shark teeth from the Miocene Epoch (23 million to 5.3 million years ago). Some of these chompers are huge—an extinct megalodon tooth can reach up to 7.6 inches (19.3 cm).
“Shark teeth are the most common finds,” says Weas, “though whale ear bones come close behind.”
Other fossils in the Cooper date to the more recent Pleistocene Epoch (2.6 million to 11,700 years ago). During this time, sea levels were lower and the Carolina coastline lay farther east.
Over the years, Weas and Harvey have retrieved the bones of Pleistocene mammoths, capybaras, hoofed herbivores—and even giant beavers. Castoroides, the Ice‑Age beaver, stood 8 feet (2.5 m) tall and weighed over 220 pounds (100 kg).
Encountering a manatee is understandably frightening, but the thought of swimming alongside an 8‑foot beaver is even more surreal.
