Yet once inside the park itself—through which Highway 441 continues, but now as a kind of tunnel through lush foliage—it is clear that you have entered a different world. The park's 814 square miles, stretching in an oblong mass across the Tennessee–North Carolina border, put it nearly on a scale with great western parks like Yosemite. But visitors who come in search of Ansel Adams landscapes may be disappointed. They will ﬁnd no glaciers here, no geysers, no heart-stopping canyons. There are, wrote one early traveler, Horace Kephart, "no ribs and vertebrae of the earth exposed. Seldom does one see even a naked ledge of rock."
Instead, these ancient, eroded mountains are covered by a living carpet of green. The vast wealth of the Smokies is in the region’s profusion of animal and plant life—riches that have only recently begun to be fully appreciated. Since 1997, a coalition of scientists, naturalists, and citizen volunteers has undertaken a treasure hunt to identify and catalog every single species found in the park. The survey is the most ambitious and sustained effort of its kind ever conducted in North America.
So far the tally stands at 14,000 and counting—among them some 600 living organisms previously unknown to science, many of which probably exist nowhere else. Most of these are not what one would call "charismatic" species: They include snails, beetles, moths, and new types of algae. Still, scientists say the ﬁndings indicate a level of biodiversity rivaled by few other places on the planet outside the great tropical rain forests. And they believe that the Smokies' ultimate species total may reach ten times the current count.
A conspiracy of factors made these mountains a near-perfect hothouse of biodiversity, according to Keith Langdon, one of the project's coordinators. The north-south orientation of the Appalachian chain helped: During the last ice age, many species took refuge from the glaciers here, fleeing southward along protected valleys. The Smokies also have a diverse underlying geology, and a heavy annual rainfall fueled by tropical air from the Gulf of Mexico. Most important, dramatic changes in elevation mean that this relatively small region encompasses a stunning variety of ecosystems. "When you hike from the lowlands to the upcountry here, it's like hiking from Georgia to Maine," Langdon said.