Explorer

Were gonna go look at banks to see which one to rob, Fossil Expeditions guide Mark Renz says jokingly, referring to our small groupÕs destination: the fossilized shell-laden river banks of the Caloosahatchee. Ft. Myers native Renz, 43, runs fossiling trips in search of remnants from a prehistoric Florida the fossilized bones of mastodons, saber-toothed cats, automobile-sized armadillos, and the six-inch teeth of giant white sharks, he says. Renz, whose past careers include country-western songwriting in Nashville, newspaper reporting, public relations, and guiding for an Everglades tour company, now gives his own eco-tours of Southwest Florida. The Lehigh Acres resident offers day trips to the Everglades, the J.N. Ding Darling National Wildlife Refuge, Bailey-Matthews Shell Museum, Six-Mile Cypress Slough Preserve, and the Edison/Ford winter estate. But it's his passion for fossil collecting that led him to start Fossil Expeditions. Renz publishes a newsletter on Florida paleontology, and his book, Fossiling Without a Ph.D., will be published in the spring by the University of Florida. He started taking groups on fossiling trips about a year and a half ago. Fossil hunting is like gambling, he says, but without the vicious side. And going to the Caloosahatchee banks sure increases your chance of finding something. Our group of fossil-shell seekers met in Lehigh at 7:45 a.m. and included Cape Coral resident Ruth Rigby and her parents, from Pensacola; and Herb and Wilma Young of Shoreline, Washington, avid conchologists who had just arrived from the Conchologists of America's annual conference in Orlando. The Youngs became interested in fossilized shells in 1981, after collecting live shells for many years. Almost all modern-day saltwater shells can be found as fossils, but Òsome fossilized shells are now extinct because the last Ice Age got to them, Herb explains. During the 40-minute ride from Lehigh to just over the line into Glades County, Renz passes around informative books to prep us for our expedition: one is on Northern Hemisphere shells, written and photographed by the late malacologist and Bailey-Matthews Shell Museum founder R. Tucker Abbott; another is RenzÕs modern edition of Angelo HeilprinÕs Explorations on the West Coast of Florida and in the Okeechobee Wilderness, first published in 1887 by the Wagner Free Institute of Science of Philadelphia, where Heilprin was a geology professor. Heilprin wrote: I would propose to designate the Pliocene series of the Caloosahatchee as the Floridian. The Pliocene epoch lasted from about 5.2 million years ago to 1.68 million years ago. The age of the fossilized saltwater shells at our intended site, a prehistoric beach, Òare about 21/2 to 3 million years old, give or take a couple hundred thousand years, Renz says. The Caloosahatchee flows west from Lake Okeechobee and empties into the Gulf of Mexico. The river is part of the Okeechobee Waterway, the 152-mile commercial link between FloridaÕs coasts. Five locks on the Caloosahatchee are managed by the U.S. Army Corps of Engineers. The river once had some 600 twists and turns, but during the past 100 years, the corps dredged and straightened it. The dredging was undertaken to increase boat traffic and drain Lake Okeechobee, which in turn drained the Everglades. When we arrive at a boat ramp on the Caloosahatchee, the sky is a bit overcast and offers a refreshing breeze. Not a pesky mosquito is in sight. Renz launches his 17-foot ganoe (six inches wider than a regular canoe and with a three-horsepower gasoline motor) and takes two people at a time to the riverbank site, about five minutes away. Look for what interests you, whether it is shell or vertebrate material, he urges. We can see fossilized shells everywhere in the cut-open riverbank, and many in the water. The river has acted like a time machine by cutting through these ancient sediments, Renz explains. Then the dredging opened it up, and now the wake from large vessels is the chief eroder in these parts. During much of Florida's 30-million-year history, the land mass was always changing. Ice was building on the polar caps and then melting while Florida was building on itself as its limestone crust was being created. FloridaÕs water would drop, then rise, and when it dropped again, more land would be exposed. The area had been land, then sea, then land, then sea at least two dozen times in the past 2 million years. The top part of the riverbank is dark-colored terrestrial or land material, about 10,000 to 12,000 years old. Then comes a thin layer of freshwater shells. The biggest part is the white saltwater shells from the Pliocene epoch. To extract the shells, Renz favors using any tool that is short and sharp. But you must be gentle, he adds. Remember, fossil hunters don't kill, they resurrect. Wilma Young uses a dandelion weeder for digging. I use my fingers to pick a bubble shell carefully out of the riverbank. It crumbles like an eggshell. ÒThey go through a real fragile state before they are fossilized, Renz explains. I pull out a tulip shell that seems fossilized, but part breaks off. It was not buried long enough to have truly fossilized and was near freshwater and fresh air, Herb Young says. ÒWhen shells are fossilized, they don't break easily. They have had time to relax; the impurities have leached out and no waterÕs around it. My eye quickly becomes more practiced, and my fossilized finds soon include a five-inch tulip shell and two small alphabet cones. Young wets one of the cones, exposing its faint pattern. The third Ice Age over Florida happened fast and the shells were buried quickly, without a chance for oxygen to get in. Thus, such fossils often still have their distinct patterns. Our group's finds include a king's crown, two rare cowrie-like shells, and a voluta. (The prized junonia belongs to the voluta family.) If the voluta were cleaned with water and bleach, and put under ultraviolet light, its characteristic brown-and-white pattern would appear. I also find several clams, a tiny horse conch, a jewel box, and many bubble shells. Young kindly gives me an auger and some other unidentified shells. Lucky Ruth Rigby finds a fossilized tooth from a snaggletooth shark. It is more than an inch long and in fantastic shape, with its serrated edges intact. The snaggletooth shark, which is extinct in this area, still lives in Asia, notes Renz. We also spot many different-sized reddish-brown fossilized pieces that turn out to be turtle shells. Some are from the pond turtle, with a shell as wide as 12 inches. Others are from the giant land tortoise, whose shell was as big as five feet across. Renz shows me a scooped-out part of the riverbank where, last year, he found a jaguar jawbone. The jaguar and other large mammals, such as the mammoth, have been gone for the past 10,000 years. We start feeling the effects of the mid-day Florida sun and begin packing up. It's therapeutic to be out here if you love nature, says Renz, as we board the ganoe. It's all-encompassing the birds, trees, tarpon, butterflies In addition to conducting his fossiling tours, Renz keeps an educational display of fossilized shells at The Shell Factory in North Ft. Myers. He also has donated one of his best finds, a 90-percent-complete fossilized dugong (prehistoric sea cow) to the Florida Museum of Natural History at the University of Florida in Gainesville. Renz found the fossilized dugong bones in a phosphate mine in Polk County. The bones are not on display for the public, however, because they need to be readily accessible to researchers. Fortunately, you donÕt have to be a professional paleontologist to recognize the truth and the fun of the sticker Renz has on the back of his boat: Fossils Take the Mystery Out of History. LG For reservations, call Fossil Expeditions at 941/368-3252 or 800/304-9432. Web site: http://www.fossilx.com and e-mail address: info@fossilx.com.