It was curiosity as much as anything that first prompted some early, hairy man to stand, look around, think and start shaping for himself a congenial environment. It is curiosity still that impels some men to forsake the cozy life and make their way dangerously again on mountain scarps, in the ragged galleries of caves and in the depths of the sea. From these special breeds—the mountain climber, the caver and the diver—there is evolving just now an equally curious hybrid: the cave diver, who now gropes through water-filled caves with a breathing unit and flippers on his feet. A man who dives in a cave solely for the thrill of living dangerously is an utter fool. But a sensible, curious diver is justifiably intrigued by the grandeur of this lost world and the welter of fossils caught in the dancing beam of his flashlight.
In this country the zeal for cave diving runs strongest in Florida for the same reason that dry cavers have been most active in the great cave areas of Kentucky. Florida is quite literally a water-soaked Kentucky, its Karstian limestone already riddled with water-filled caves, with more being made all the time. The 500 million gallons of water now flowing daily from a single Florida source, the well-touted and beautiful Silver Springs, is almost twice the volume of any other springhead in the world. Early in this century geologists computed that the flow from Silver Springs alone was dissolving about 600 tons of Florida's insides every day.
A layman can get some idea what is going on under Florida through the cracks in the floor. With the collapse of limestone bedding, new sinkholes frequently appear and expand into ponds, and old ponds sometimes vanish as if the plug were pulled. A north Florida farmer, fertilizing pasture astride a Farmall, may hear a sudden "whump" behind him, and there, cut sheer in the flat pasture, will be a crater, sometimes a crater big enough to swallow farmer, Farmall and all. In 1892 a 16-square-mile lake, Alachua, disappeared, stranding thousands of fish and several steamboats.
Four years ago, in the cave of Silver Springs, where exploration is strictly limited to men of guaranteed competence, two divers found tusks, teeth and other fragments of extinct mammoths. The cave entrance is wide, but barely high enough for one of these old elephants. Did the bones come rattling through one of the narrow fissures that pours water into the main cave? Was the cave ever dry and were mammoths ever butchered there by early man? In a state where man can only be dated with certainty back about 4,000 years, archaeologists would be happy to confirm such things, but for lack of evidence it remains a conjecture. For 100 years Floridians have been finding the fossils of extinct mammoths, mastodons, tapirs, deer, camels and saber-toothed tigers here, there, almost everywhere under open water, which because of its generally high calcium carbonate content is an excellent preservative. To prove the coexistence of man and any of these extinct beasts demands finding some record of man and animal fossil in close physical "association," such as a hunter's spear in the skull of a tiger or a hunter's arm, say, in the tiger's mouth. Even such close associations are not wholly reliable in Florida, for its waters are both a great preserver and a great confuser. A single pothole may yield a wish-wash of relics of various dates drifted in from far separate places. In one sinkhole that bore some promise of fossils, cave divers found three airplane engines. One amateur paleontologist, carefully brushing the silt from a mastodon jaw, found next to it a spear point and under both of them a Lincoln penny.
The most extensive, exhausting and deep assault on any water-filled cave has been going on now for almost a year in Wakulla Springs, 15 miles south of Tallahassee, Fla. Beyond the light of day in Wakulla, a team composed of Andy Harrold, an editor of the Florida State News Bureau, and four undergraduates, Gary Salsman, Wallace Jenkins, Henry Doll and Gordon Whitney, have found a seemingly inexhaustible supply of bone spear points on a bone-littered floor. Such bone points are figured to have been the most common weapon of Florida man more than 4,000 years ago, but an abundance in itself proves nothing. The divers work only in the hope that from such a rich harvest of the past they can glean something meaningful.
A protruding underwater ledge casts a curtain of shadow over the entrance to this Wakulla's Cave. It has been called the largest spring mouth in the world, and any diver penetrating the shadow under the ledge believes this must be so. It is 103 feet from the surface to the bottom; it is 200 feet wide. As he slips down under the white bellies of indolent bass and past a pitted ledge of catfish and furtive eels, the diver enters a twilight world. He may notice here some similarity between this cave and a dry cave. On the right side for 200 feet he passes over great masses of angular breakdown of the sort usually found in the old, upper galleries of a dry cave. During glacial advances sea level dropped below the floor of the cave. Was any part of it ever dry or habitable? One geologist says it is possible but most improbable. Another says it is possible but almost impossible to prove. Two hundred feet in, the breakdown on the floor rises within 10 feet of the ceiling and extends across the whole floor, damming the slide of sand that stretches down on the left side from the opening. Here, at the mounded rocks, 180 feet deep, the divers simultaneously cross two thresholds. The twilight here becomes utter darkness and each man's senses are caught in the first irrational grips of depth rapture. The first disarticulated jumble of mammoth bones lies beyond the rocks. To one diver at first sight one leg bone looks seven feet long, and that would make the whole mammoth about 18 feet tall, but in his mild rapture the diver has merely forgotten that everything looks a bit bigger under water.
On their most recent push into Wakulla, Divers Harrold and Jenkins picked their way by flashlight from one familiar bone marker to the next, from antlers to a vertebra, to loose mastodon teeth and a tusk, and then to a mastodon jaw and on to another jaw and finally, 500 feet inside the cave, to a depression in the floor. Harrold plays his light over charred wood and begins sifting the soft gray silt in the depression. Is this an old firesite? Is the deep depression farther along an old water hole? Are the small bones piled thick for 18 feet at the corner a refuse site? Perhaps, but probably not. Jenkins taps three times on his air tank. They have been five minutes at 240 feet. They will need the rest of their air to decompress. Next weekend they will spend two more days for 10 minutes of work.
Turning one of the smooth bone spear points over in his hands a short while ago, Andy Harrold said thoughtfully: "All of these could have fallen in some hole farther along and been washed down, and so could the bones and wood. But why do we find only these points and no flint, no pottery? There are curved tusks down there. Did you ever try to roll a curved tusk even in water? With all the trees dying and limbs falling into sinks, why do we only find burned wood? We keep thinking we might find the answer by going deeper. We know the cave gets bigger, but we're already 250 feet deep and working drunk all the time. We don't want to add ourselves to the bone pile."