New digging in an old hole

Natalie Angier has an article in The New York Times about digging around the Panama Canal:

You can’t leave Aldo Rincón alone for a moment. As a small knot of scientists and visitors dressed in hard hats and orange safety vests milled around on the banks of the Panama Canal, chatting about the $5 billion expansion program now under way to widen the storied canal and so accommodate the ever-fatter freighters that ply the planet’s seas, Mr. Rincón, 30, quietly pulled a few digging tools from his backpack. He squatted down near an unremarkable-looking patch of pebbles and broken rock and began methodically scraping away in the dirt. The helmeted throng wandered off briefly to inspect a sloping chop of sedimentary and volcanic layer cake that the construction project had exposed nearby. On returning to Mr. Rincón and his rasping trowel, scientists and guests alike gasped with amazement. In a mere fifteen minutes of work, Mr. Rincón, a paleontology intern with the Smithsonian Tropical Research Institute, had unearthed a big, beautiful fossilized femur bulging up pertly from a sedimentary substrate. The bone was about seven inches long and so flawlessly preserved it looked fit for a soup pot.
Mr. Rincón, tall, slender, monkishly focused, and wearing sideburns, fashionable black plastic-framed glasses, and a braided leather bracelet, guessed that the femur belonged to an extinct species of llama that lived in the area some 20 million years ago. He should know: he has found llama bones before, as well as the mineralized mementos of prehistoric crocodiles, peccaries, anacondas, and giant tortoises. One of his discoveries, of a partial skull from a leaf-eating horse, was described in the May issue of the Journal of Paleontology, in an article by Bruce MacFadden of the Florida Museum of Natural History.
“Aldo has an amazing ability to find fossils,” said Camilo Montes, his supervisor at the Panamá Geology Project. “Whenever he digs, he finds another fossil.”
These days, Mr. Rincón and scores of other scientists are digging as fast as they can in the shadows of the really big dig that is the Panama canal expansion program, the most ambitious overhaul to the complex array of locks, channels, dams, and bridges since the canal was built a century ago.
The Panamanian government initiated the project for purely economic reasons. In its current configuration, the 51-mile shortcut between the Pacific and Atlantic Oceans can grant passage only to boats carrying up to 65,000 tons of cargo. But many international shipping companies increasingly prefer to use mega-freighters that can haul up to 300,000 tons. As a result, the Panama Canal has been losing business to other transoceanic routes; and with canal tolls amounting to close to $100,000 per ship per one-way crossing, and potentially more for the giant freighters, the government decided it had no choice but to widen and straighten the canal to make room for the SUV’s of the seas.
For scientists, the massive engineering project promises spectacular spinoffs. The tropics are thought to be nature’s romper room, the habitat where the majority of the world’s life forms got their start and thus of great interest to evolutionary scholars. Yet the very conditions conducive to biological diversity and innovation end up obscuring life’s biography. The sun, the water, the greedily growing plants: nothing remains exposed for long, and fossil evidence is pushed ever deeper beneath successive pages of growth and decay.
Tropical verdure also masks tropical geology, the underlying story of how the landscape came to be. This blurring is a particular shame in the case of the Panamanian isthmus, given its pivotal role as a bridge between two continents. Geologists have longed to understand how and when the isthmus arose, but the tropics aren’t Arizona and there is no Grand Canyon to serve as an open book.
The five-year Panama canal expansion project, begun last year, offers scientists a kind of drive-by canyon experience, a brief yanking back of the chlorophyll cloak. Using dynamite, bulldozers, backhoes, excavators, and many, many shovels, workers will be rearranging hundreds of millions of cubic meters of dirt and rock. “There’s nothing else like it, to get this much exposure in the tropics,” Dr. Montes said. “We cannot lose this scientific opportunity.” Carlos Jaramillo, also of the Smithsonian, said, “We know we’re just guests here, but at least they’re digging us a $5 billion hole.”
At the canal there are neither slow boats nor rain checks. The moment workers blast open a new cut, researchers must move in immediately and gather what data they can. Not only is the jungle always ready to reclaim naked land, but the canal authorities are similarly devoted to quick forest restoration, and they will add topsoil where needed to spur a fresh round of stabilizing vegetation. They want no repeat of the many tragedies that accompanied the building of the original canal, when thousands died in landslides because the terrain had been too quickly stripped bare. “We’re in a race against time,” Dr. Jaramillo said.
Speed dating for scientists has already borne fruit. Through analyzing more than 2,000 fossils, the stratigraphic record revealed by each new rock cut, paleomagnetic data, isotope ratios, carbon signatures and more, researchers are getting a sense of what an ancient tropical rain forest looked like.
Some fifteen million years ago, when Panama served as the southernmost outpost of the North American continent and the land bridge had yet to form, the forest was nevertheless a crossover dream. Its fauna, according to Dr. MacFadden of the Florida museum, was similar to the animals then living in Florida and Texas, which means leaping llamas and leaf-eating horses that looked like large tapirs, and mid-size tapirs that looked like tapirs, and forest rhinoceroses, and an especially fierce carnivore that was half-bear and half-dog. Yet the flora looked South American, the apparent result of seeds traversing the ocean on currents of water or wind and finding friendly soil in the Panamanian swelter.
Starting around ten million years ago, the isthmus of Panama began to form, and researchers are finding that the tiny country is one of the most geologically complex places on earth, part Caribbean, part North American, part a tiny piece from an island in the middle of the Pacific, part a tiny piece from an island arc. “Four tectonic plates are involved, and all of them are colliding in Panama,” Dr. Jaramillo said. “You won’t find that sort of tectonic plate configuration anywhere else in the world.” Moreover, while most of the world’s tectonic plates are rigid, now slamming together, now breaking apart, the plates of Panama are rubbery. “They seem to be bending, and we don’t know why,” Dr. Jaramillo said. Maybe they’re warming up for the day when, high over their head, the revamped locks are opened and the wide loads start coming through.