t is like diving into an abyss, or venturing into a black hole in space. What little sunlight there is quickly dissipates the deeper you go. Marine archaeologist John Gifford has plunged into these murky depths on numerous occasions. And each time it doesn’t get any easier. “You’re swimming down this giant funnel,” says Gifford, describing the 220-foot-deep Little Salt Spring, an hourglass-shaped sinkhole on Florida’s Gulf Coast. “And as you get to the neck of the funnel, 40 feet down, you literally come upon a circle of rock that represents the actual opening into the cavity. It’s like standing on the edge of the Grand Canyon, except that you can’t see anything but darkness below.”

You might wonder why Gifford, an associate professor at the University of Miami Rosenstiel School of Marine and Atmospheric Science, makes the dive at all. But it is crucial that he dives deeper, for the sake not only of his own research but also for the very history of civilization. For somewhere, still waiting at a depth yet explored, perhaps lies evidence of people’s earliest presence in the Western Hemisphere.

“Already we have found some remains that are 7,000 to 8,000 years old,” explains Gifford. “But what’s remarkable is that we have even found brain tissue with some of the remains. It’s truly one of the most intriguing archaeological sites in North America.” A land development company donated the sinkhole to the University in 1982. Ever since then, Gifford has been exploring the site either alone or with small groups of graduate students, who scuba dive into the sinkhole and carefully remove artifacts from different levels.

he sinkhole is an archaeologist’s dream come true. Located in southern Sarasota County about five miles from the Gulf of Mexico, it has yielded a treasure trove of well-preserved ancient relics, including the bones and teeth of mastodons and giant sloths, and wooden artifacts dating back 8,000 to more than 12,000 years ago. The oldest item found so far: a sharpened wooden spear carbon-dated some 12,200 years old. It was used to kill an extinct species of giant land tortoise, whose shell was found surrounding the spear on a ledge 85 feet below the surface.

But the most important discoveries are yet to be made. Gifford and his students could be on the brink of finding human remains older than Kennewick Man, whose 9,200-year-old skeleton was discovered four years ago in the state of Washington. Human remains and artifacts already recovered from the sinkhole as well as evidence of early human habitation in the surrounding area of the site are strong indicators that they will.

A human skull with preserved brain tissue was found at the site by scuba divers in the late 1950s. Evidence of a very early settlement near the sinkhole dating back 6,000 to 7,000 years also was found, when archaeologists working at the site in the 1970s discovered some 100 to 1,000 burials nearby. Test excavation of two burials showed remarkable preservation of bodies, including fatty tissue, hair, and fingernails still intact.

“Little Salt Spring could open a very clear window into the earliest period of the Paleo-Indian settlement of Florida,” says Gifford.

That anything—especially human remains—could survive for so long is a remarkable story in itself. But it is the delicate chemical makeup of the water in this 75-yard-wide sinkhole that has made it so. Water in the sinkhole is brackish and nearly devoid of oxygen, and it is this anoxic water that has served as a natural preservative for thousands of years.

“This is water that has its own chemistry; there’s almost no microbial activity, and no bacterial decomposition,” says Gifford. “It has preserved incredibly well some of the material that on land simply doesn’t last more than a couple of hundred years. Little Salt Spring is not only an archaeological site but one of the most intriguing geological sites I’ve ever investigated.”

If anyone should know, it is Gifford. He’s been studying prehistoric underwater sites for a good portion of his life. His primary interest, he says, lies in the relatively little-studied area of searching for remains of human settlements that have been submerged since the end of the last ice age.

“Prehistoric sites on the continental shelf mostly,” says Gifford. “It turns out that Little Salt Spring is an example of one of these sites—one that was exposed to the air 10,000 or 12,000 years ago because the water table here in Florida was more than 200 feet lower than it is right now.”

nderwater archaeology is a painstaking process compared to the excavation of a site on dry land. It oftentimes requires an even greater deal of time and patience—and money.

Says Gifford: “The rule of thumb that has emerged from several decades’ worth of underwater work is that, all other things being equal, it costs about ten times as much to excavate an underwater project as a comparable land project.

“Then you have the obvious problems of working in an alien environment and being completely dependent upon your scuba equipment,” he says. “If there’s a mechanical failure, then you have a major problem to deal with.”

Diver-to-diver communication is accomplished by writing messages on a plastic board. “A very tedious process,” he says. “But the one factor that really limits the time we can spend underwater is water temperature. It’s a constant 73 degrees Fahrenheit. That may sound warm, but after an hour or two of being submerged in 73-degree water, unless you have a really warm wet suit or dry suit, you get very, very cold.”

Despite such difficulties, Gifford and his students press on, for they know that one of the most significant discoveries in the history of archaeology is within their reach. Given the artifacts and human remains already discovered at the spring, it seems likely that it is only a matter of time until they locate the oldest-known skeletal remains. Unfortunately, it also is a race against the clock.

The sinkhole, located in North Port, Florida, halfway between Fort Myers and Sarasota, is part of one of the state’s most rapidly developing regions. Residential communities, schools, and golf courses now surround the site. Gifford is afraid that water runoff and other pollutants from encroaching development could imperil the sinkhole’s chemistry and accelerate the decay of artifacts and human remains.

“We need to monitor the water quality of the sinkhole over the coming years to make sure that we don’t see any changes in the water chemistry,” says Gifford. “Or we could lose what’s literally a natural time capsule to the very earliest human occupation of this peninsula.”

Uncovering Ancient Treasures

oes Noah’s Ark lie hidden somewhere in Turkey beneath tons of rock, sand, and soot? Did visit-ors from outer space, using technology light-years ahead of earth, build the Great Pyramids of Egypt?

While such questions might sound like a promo for an episode of the old television series In Search Of, they’re precisely the kinds of claims marine archaeologist John Gifford and his students spend an entire semester investigating in a course called Fantastic Archaeology.

“Most claims like these are undoubtedly myths,” says Gifford, an associate professor at the Rosenstiel School of Marine and Atmospheric Science. “But what the course is designed to do is challenge students to think logically and to analyze arguments from different perspectives.”

Two hundred miles to the northwest of the school, in the town of North Port on Florida’s Gulf Coast, there’s nothing mythical about a 220-foot-deep prehistoric underwater sinkhole called Little Salt Spring. Gifford and students from his Fieldwork in Prehistoric Underwater Archaeology course have been exploring the site since it was donated to the University in 1982, scuba diving into the sinkhole and carefully removing artifacts.

Among their and earlier divers’ discoveries:

• The portion of an oak throwing stick archaeologists call a “nonreturn-ing boomerang.” It is at least 9,000 years old and is similar to weapons found in Australia, ancient Egypt, and Western Europe.

• A previously unknown type of wood-en tool called a “putter,” so named because of its similarity to a golf club.

• A large ancient cemetery on the boundary of the sinkhole containing 100 to 1,000 burials.

• A 7,000-year-old human skull with preserved brain tissue.