YELLOWSTONE NATIONAL PARK, Wyo. — It began more than five years ago as a simple personal challenge: Visit each of the 50 or so known waterfalls in Yellowstone National Park and look for others missing from park maps.
"We would have been thrilled to find three or four waterfalls that had never been documented before," says Paul Rubinstein, who began stalking waterfalls during time off from a summer job in the park gift shops.
Rubinstein and fellow waterfall hunters Lee Whittlesey and Mike Stevens have since documented and named nearly 230 Yellowstone waterfalls never before mapped, named, photographed or described, a feat of exploration rare in the modern world, especially in a national park visited by more than 3 million people each year.
Along the way they ran into grizzly bears, were struck by lightning and happened onto a remote and rugged section of the park so laden with towering waterfalls they named it "Valhalla" after the lofty realm of Norse mythology.
The modern-day Corps of Discovery tell the story of their quest and describe the approximately 280 waterfalls now known in the park in a new book, "The Guide to Yellowstone Waterfalls and Their Discovery," due out in July from Westcliffe Publishers.
In 320 pages and more than 200 photographs, the book contains what may be one of the greatest records of geographical discovery in Yellowstone since the first reports of the surveys that probed the geyser-filled wilderness before the turn of the century.
Some park veterans fear the book gives away the very secrets that make Yellowstone such a wondrous place to explore, but others see it as an engaging reminder of how much remains to be found even in an age of Global Positioning System technology.
"The people who were credited with the discovery of Yellowstone and its main features all came over a relatively short period of a few years just before and after it became a park," says Judith Meyer, an assistant professor of geography at Southwest Missouri State University and an authority on the park's geographical history who wrote the foreword for the waterfall book. "It's been 125 years, and nothing this big has come out of the park since then."
The newly documented waterfalls include many of the tallest and most spectacular in Yellowstone, although few rival the dimensions of the well-known Upper and Lower Falls of the Yellowstone River. The number of falls in Yellowstone may surpass the total found in Yosemite National Park, which is famous for its waterfalls.
The new book's three authors and others who searched out Yellowstone's falls with them coined names they hope reflect the character of each one.
Citadel of Asgard Falls, for instance, plunges 150 feet into a rocky amphitheater before cascading hundreds of feet farther. Rapunzel Falls dives at least 400 feet and wins its name from its resemblance to the golden hair of the fairy-tale maiden. Zephyr Falls, 300 feet high, weaves elegantly in the slightest wind. Stone Hollow Falls drops through a crevice in a cliff.
And the book's authors doubt they have found all of Yellowstone's watery wonders.
"At the beginning it seemed like every time we went out looking for a waterfall we'd heard about somewhere, we'd find three more we had never heard about," says Stevens, a high school math teacher in California who works summers in Yellowstone as a tour guide. "I'm convinced the park is still teeming with undiscovered waterfalls, but they're even more difficult to access."
During his first summer in Yellowstone, in 1979, Stevens heard a ranger discuss the park's waterfalls and decided he would like to see as many of them as he could. In 1989 Rubinstein joined him, and on their days off, they searched out little-known falls.
A few years later, Rubinstein and Stevens ran into Whittlesey, Yellowstone's official archivist, who had already begun work on a book encompassing the some 50 falls he had identified from park maps and historical records. The three joined forces, with Whittlesey compiling the written descriptions of waterfalls and Rubinstein and Stevens photographing them.
Then in 1995, while poring through the park archives, Rubinstein began finding mentions of "barriers" to fish migration that sounded suspiciously like waterfalls. He took it as a hint that many more unmapped falls might be lurking in the park's back country.
"I said, 'There may be a lot more out there that we could include in the book if you guys wanted to,' " Rubinstein recalls.
The three agreed to delay the book while they investigated their new leads. In 1996, which they now call a "year of discovery," they found more than 20 waterfalls never before mapped or photographed. They lengthened the list in successive years, including only falls at least 15 feet high.