The Yellowstone-Grand Teton region was not officially discovered and its scenic marvels were not publicly proclaimed until the 1870’s, beginning with the Washburn-Langford-Doane expedition. For thirty years before, from 1841 to 1869, this region was a Paradise Lost, rarely visited by white men. But for thirty years before that, or from 1807 to 1840, this region had hundreds of appreciative visitors. These were the Rocky Mountain fur trappers. While searching for the golden-brown fur of the beaver, destined for the St. Louis market, these adventurers thoroughly explored this fabulous region. Although news of their discoveries received scant public notice back in the settlements, or was discounted as tall tales, to them belongs the honor of being the first actual explorers of these twin parks. Neighboring Yellowstone and Grand Teton, established as National Parks in 1872 and 1929, respectively, are separately managed today as units of our National Park System. But geographically, now as well as in the early nineteenth century, they embrace one unique region, characterized by topographic and geologic features that are the crescendo of a great scenic symphony. Here, at the heart of the continent, the source of the three major river systems of the continent—the Columbia, the Colorado, and the Missouri-Mississippi—may be found the greatest geyser basins, the largest mountain lake, the most colorful of kaleidoscopic canyons, one of the richest arrays of wildlife, and one of the most spectacularly beautiful mountain ranges in the world. The Yellowstone-Grand Teton region has historical unity, also, particularly during the obscure but heroic age of the Rocky Mountain fur trade. “Colter’s Hell”—bearing the name of the legendary discoverer, and conjuring up visions of a primitive “Dante’s Inferno”—is the term which visitors today associate with the early history of Yellowstone National Park and its universally famous hydrothermal wonders. Actually, the wandering, bearded, buck-skinned beaver trappers never referred to the geyser region of the upper Madison as Colter’s Hell. As we will see, the real Colter’s Hell in Jim Bridger’s day was another place altogether, having nothing to do with anything within Yellowstone Park itself. In trapper times the Yellowstone geyser area had no fixed name but was variously described by them as a region of “great volcanoes,” “boiling springs” or “spouting fountains.” On the recently discovered Hood and Ferris maps (see below) it is labeled “the Burnt Hole” (although this name seems to have been restricted by Russell and others to the Hebgen Lake Valley). Captain Bonneville tells us that his men knew of this region as “the Firehole” and this name, as applied to the river draining the geyser basins, survives today.