U.S. route 395 is a geologic master class disguised as a road. It runs north from the arid outskirts of Los Angeles, carrying travelers up to Reno along the eastern flank of the Sierra Nevada. On the way, they pass the black cinder cones of Coso Volcanic Field and the eroded scars of a mighty 19th-century earthquake near Lone Pine. In winter, drivers might see steam rising from Hot Creek, where water boils up from an active supervolcano deep underground. About an hour from the Nevada border, Mono Lake appears, with its bulbous and surreal mineral formations known as tufa towers. Even for someone with no particular interest in rocks, these are captivating, otherworldly sights. But for James Faulds, Nevada’s state geologist, they are something more—clues to a great tectonic mystery unfolding in the American West. If he’s right, all of this, from the wastes of the Mojave Desert to the night-lit casinos of Reno, will someday be beachfront property.

For more than a century, the San Andreas Fault has been considered the undisputed heavyweight champion of large-scale deformation in the West. It is here that the North American and Pacific Plates meet, jostling for position with often violent results. Eventually, the theory goes, the thin sliver of land between the fault and the ocean—from the southern tip of the Baja Peninsula to the Santa Cruz Mountains—will break off from the mainland and slide north, until LA drifts past San Francisco. But there’s at least one problem with this scenario: The San Andreas appears to have gotten jammed. Northwest of LA, near the town of Frazier Park, the fault is kinked out of alignment so dramatically that many geologists suspect the pent-up tectonic strain will have to seek release somewhere else.

Faulds thinks he’s found the spot. It’s an emerging zone of instability, known as the Walker Lane, that closely follows Route 395. He believes that, over the next 8 million to 10 million years, the North American continent will unzip along this stretch of land, east of the San Andreas. The Gulf of California, which separates the Baja Peninsula from Mexico, will surge north into Nevada, turning thousands of square miles of dry land into ocean floor. (Mapmakers, if they still exist, may label the new body of water the Reno Sea.) While this geologic realignment will take long enough for human civilization to fall, rise, and fall again hundreds of times over, Faulds’ hypothesis is more than an academic curiosity. It represents a radical shift in how geologists use up-to-the-minute tools—satellite data, aerial surveys, computer simulations—to fathom age-old processes. And for residents of the West, it is an invitation to think in an altogether new way about the familiar-seeming ground beneath them. Now is the time: Already the Walker Lane region, with its booming population and burgeoning tech economy, is beginning to feel the rumblings of a new seismic regime.

Many of Faulds’ colleagues dismiss his idea as controversial, fundamentally unprovable, or even simply wrong. It may be difficult to persuade them otherwise: Unlike the San Andreas, which is visible from space, the Walker Lane has yet to form a single, continuous line across the landscape. Still, Faulds has a pretty good idea of where it begins. Using a combination of old-fashioned fieldwork and modern technologies, he is now busily trying to find the rest. Last fall, I drove the nearly 500 miles up Route 395 from LA to Reno to meet him and learn how his tectonic premonition might come to pass.