Photo: Courtesy of the Mammoth Site
This past summer, I found myself standing in an air-conditioned pit, trowel in hand, digging for mammoth bones, while tourists watched me work from behind a fence. I was helping Larry Agenbroad, whose Mammoth Site project in Hot Springs, SD, is one of the oldest affiliated with the Earthwatch Institute, an organization that supplies field investigators on tight budgets with the motivated, unpaid volunteers they need to accomplish their work.
Agenbroad knows only too well that many scientists regard the idea of doing science with people that more or less walk in off the street as absurd. "My colleagues used to give me a lot of flak about that," says the Northern Arizona University geology professor. But after "picking crews every way you can--grade point average, experience, degrees," he prefers to explore his vast pit with vacationers sent by Earthwatch, two crews of 12 each July, each dig lasting two weeks. Conscious of their inexperience, Earthwatch volunteers "are afraid to do something wrong," so they pay close attention to his instructions. That makes them better than grad students, he says, who know less than they think they do.
Agenbroad assigns his charges tasks for which they can be quickly trained and then supervises them closely. Under the wrong investigator this could turn a crew into an imitation of a chain gang breaking rocks, but Agenbroad and crew chief Don Morris, a former National Park Service archeologist, keep a lighthearted grip on the reins. In fact, Agenbroad is a master at keeping vacationers happy. People enjoy his common touch, says Bob Hardy, a former student: "Agenbroad makes everybody feel like somebody." Add in good food, field trips, afternoon Popsicle breaks, and hilarious lectures on mammoth paleontology, and you have Agenbroad's recipe for keeping spirits high and revved up to discover bones.
Thus science happens for all comers. Besides one science journalist, our crew this summer included a bookseller, schoolteachers, a biology major, a credit union employee, an architectural lighting designer, a retired professor of audiology, a former technician for a biotech company, someone thinking about paleontology as a career, and Agenbroad's remarkable friend Vee Lamb, an 85-year-old former "girl Friday," back for her 14th summer in the pit. Each paid $1,645 to be there (tax-deductible as a contribution to nonprofit Earthwatch).
Photo: Courtesy of the Mammoth Site
More than 130 Earthwatch scientists, working on five continents, now use variations on the motivation formula Agenbroad has used since 1976. Each year, Earthwatch, headquartered in Maynard, Mass., sends more than 4,000 volunteers around the globe on expeditions catering to every scientific taste. Researchers get enthusiastic, willing bodies; participants get memories to last a lifetime. You can study medicinal plants in Kenya or monitor the incidence of intestinal parasites in Cameroon. You can hunt for fluorescent proteins in marine denizens off Australia's Great Barrier Reef or measure mercury levels in loon populations in Maine. Maybe you'll monitor climate change at the edge of the arctic or study dolphins off the Spanish coast. Or perhaps you can help survey Russia's Lake Baikal, the world's largest lake.
AIR-CONDITIONED PALEONTOLOGY But of all the experiences Earthwatch offers, digging at the world's greatest repository of Columbian mammoth remains has got to be hard to top. The Columbians (Mammuthus columbi), like their better known cousins, the woolly mammoths (M. primigenius), inhabited North America for well over one million years before dying out about 11,000 years ago. Lacking the woollies' heavy coats, they ranged as far south as Mexico. Taller and heavier than the woollies, typically standing four meters high at the shoulder and weighing nine metric tons, they resembled an outsized version of today's Asian elephants. But a modern elephant could pass under a Columbian's chin with room to spare.
We learned how to encase bones in plaster casts, map where bones are discovered, screen earth for small fossils of other species (37 to date), and estimate a mammoth's age by measuring its teeth. But our main task was to remove the tan-colored limonite and gypsum sediments that cover the bones--in other words, to move dirt. And there is plenty of it. There is dirt, dirt, dirt, more dirt, still more, and occasionally, coaxed into view by dental picks and brushes, a bone--anything from a 2.5-meter-long tusk to a foot bone the size of a baby's fist.
While we worked, tourists looked on, fascinated by the action and the fruits of previous digs--mammoths' bones displayed in the pit in situ, exactly as they settled after the animals died. Tourism--over 100,000 visitors a year--keeps the Mammoth Site solvent. Ticket and gift shop sales finance a mammoth museum, a visiting scientist program, symposia, and of course, the climate-controlled 23,000 sq.-ft. building covering the elliptical pit roughly two-thirds the size of a football field. Air conditioning, an unheard-of luxury at a dig site, is not only expected by tourists during the scorching summer, but is essential to preserve the bones, which unlike dinosaur bones are too young to have turned into rock.
THE EARLY DIGS Around 26,000 years ago, the excavation site was a shale-lined sinkhole filled with warm water from a thermal spring. In winter, heat from the spring would prevent snow from covering vegetation at the pit's edge, creating, in the eyes of hungry mammoths, a walk-in salad bar. It was an alluring--and deadly--place for mammoths to congregate: at least 52 (49 Columbians and three woollies) came too near the edge, fell in, and never got out.
Over a period of several hundred years, sediments covered the bones of perhaps 100 leviathans. Those sediments would prove far more resistant to erosion than the surrounding shale: Thousands of years of erosion erased so much of the sinkhole shale that the sediments left in place acquired a new appearance, that of a small hill. In 1974, when a bulldozer was leveling the hill as part of a housing development project in Hot Springs, it sliced through what looked like a tusk. The operator, George Hanson, showed the tusk and other bones to his son Dan, who invited his former professor Agenbroad to take a look.
Photo: Courtesy of the Mammoth Site
"At first, I thought it was a mammoth kill," Agenbroad recalls, a site where early hunters butchered mammoths. But radiocarbon dating of the bones soon ruled that out. The mammoths died long before humans arrived in North America 15,000 years ago. The land's owner, Phil Anderson, found the idea of mammoth fossils intriguing and gave Agenbroad three years to explore the hill. The following summer Agenbroad spent the only grant money he could secure, $500, to feed his students as they began the site's inaugural excavation. A year later he began his association with Earthwatch. When it became clear that the little town at the southern tip of the Black Hills possessed an enormous mammoth graveyard, Anderson sold the land at cost to the Mammoth Site of Hot Springs, a nonprofit corporation set up to let Agenbroad develop the site.
MOVIE STARS Success has brought Agenbroad invitations to study mammoth remains around the world. In 1994 he was invited to excavate a nearly complete pygmy mammoth skeleton found in Channel Island National Park, 40 km off the coast of Santa Barbara, Calif. Pygmies (M. exilis) descended from Columbians, who swam to the islands when the Ice Age made sea levels lower and the four Channel Islands formed a single super-island closer to the mainland. Over 30,000 years the animals adapted to the island's limited food supply by evolving into mammoths only half as tall as Columbians.
In 1999 Agenbroad was the only American scientist on the international team that dug up an intact wooly mammoth frozen 23,000 years ago in Siberia's Taimyr Peninsula. The Discovery Channel filmed the expedition for television in Raising the Mammoth. Last year Agenbroad and Morris were filmed during their annual Channel Island trip to search for more pygmies. That show was called Island of the Pygmy Mammoths. Parents may not recognize Agenbroad from cable television documentaries when they tour the Mammoth Site and see him roaming the building, but some of their kids do, and treat him like a movie star.
"Every person wants to be Indiana Jones," he says, referring to the swashbuckling movie archaeologist in Raiders of the Lost Ark. Life does not work out that way for most of us, but "here you can do that for two weeks." That is why volunteers will come next July and Julys after that for years on end, to find more bones and flesh out the story of what happened in the pit thousands of years ago. As long as Agenbroad remains, each year's volunteers will end their dig in the same emotional turmoil as this year's, knowing he speaks the truth when he says, "When we put you back on the plane, you won't want to go."
Tom Hollon (email@example.com) is a freelance science writer in Rockville, Md.