Eighty million tons of rock, moving at more than one hundred miles an hour, just fell off the mountain, traveling with such force and momentum that the leading edge of the landslide ran four hundred feet up a mountain on the other side of the valley. Along its path lay part of the Rock Creek Campground. Twenty-eight campers were killed, nineteen of them buried too deep ever to be found again. The devastation was swift but heartbreakingly fickle. Three brothers, sleeping in one tent, were spared. Their parents, sleeping in another tent beside them, were swept away and never seen again.
A big earthquake—and I mean big—will happen sometime, Doss told me. "You can count on that. This is a big fault zone for earthquakes."
Despite the Hebgen Lake quake and the other known risks, Yellowstone didn't get permanent seismometers until the 1970s.
If you needed a way to appreciate the grandeur and inexorable nature of geologic processes, you could do worse than to consider the Tetons, the sumptuously jagged range that stands just to the south of Yellowstone National Park. Nine million years ago, the Tetons didn't exist. The land around Jackson Hole was just a high grassy plain. But then a forty-mile-long fault opened within the Earth, and since then, about once every nine hundred years, the Tetons experience a really big earthquake, enough to jerk them another six feet higher. It is these repeated jerks over eons that have raised them to their present majestic heights of seven thousand feet.