Kemmerer (pronounced “Kemmer”) is a scrappy little community of 2,400 people, proud home to a sometime-state-champion high school football program and also to the “mother store” of the J.C. Penney retail chain, founded in 1902. A statue of James Cash Penney himself presides over the center of town, right hand held out as if for payment.
But geology has always been the real key to Kemmerer’s existence. You get a hint of that from a high looming mass called Oyster Ridge, which runs parallel to the town, and from the way subterranean forces seem to flex and shoulder their way across its thinly vegetated hillsides.
At Fossil Butte National Monument, a few miles out of town, curator Arvid Aase—imagine Bruce Willis as a geology teacher—delivered a lesson on the geological origin of the area, complete with sound effects. His right hand pushed across the back of his left to mimic “thrust sheets sliding in from the west—r-r-r-r-rrrrrrr.” These massive stone plates slowed down, he said, as their overlapping movement generated increasing friction—“u-u-u-r-r-r-r-r-RRRR.” Then his upper hand curved up, like a wave breaking, to mimic the leading edges of the thrust sheets pushing up to form Oyster Ridge and, a few miles behind it, a secondary ridge.
In the 19th century, Kemmerer sprung up in the valley between the two ridges. The thrust plates had pushed coal from the Cretaceous era, more than 65 million years ago, up near the surface. From the 1880s on, underground coal mining became the town’s lifeblood and its heartbreak: An explosion in one mine killed 99 men a century ago next year. An explosion in another mine killed 39 a year later. The coal continues to come out of the ground today, not from underground mines but from a long black streak of strip mine in the second ridge, just outside town. That mine and the adjacent coal-fired power plant are still among Kemmerer’s top employers.
Geology had one other major effect, according to Aase, and it is the source of Kemmerer’s modern renown: The movement of the thrust sheets hollowed out a deep basin behind that second ridge. There, roughly 52 million years ago, Fossil Lake spread out across an area of about 1,500 square miles. It was part of a larger system of three great lakes, now called the Green River Formation. The dinosaurs had vanished, along with three-quarters of life on earth, in the mass extinction at the end of the Cretaceous, 65 million years ago. So Fossil Lake flourished in the long post-apocalyptic recovery called the Eocene Epoch. Early modern mammals rose up then, liberated from dinosaur tyranny. So did modern birds, taking the place of the pterosaurs that had formerly ruled the skies.