Lake Lahontan, The Ocean That Was Here Before the Desert

Stand anywhere in the Reno basin and look at the mountains surrounding the valley. Roughly midway up their slopes, on many of them, you can make out a horizontal line, a faint terrace, a subtle change in the rock. That line marks the ancient shoreline of Lake Lahontan, and it tells you that where you are standing, not so very long ago in geologic time, was the bottom of a lake.

Lake Lahontan was a massive prehistoric body of water that covered much of northwestern Nevada during the last ice age. At its peak, approximately twelve thousand seven hundred years ago, it stretched across more than eight thousand five hundred square miles, more than a third the size of Lake Huron today. Its deepest points reached about nine hundred feet. The Truckee River valley, the Carson Sink, the Humboldt Basin, all of it was submerged.

The lake existed because the climate was different: colder, wetter, with far more snowpack in the Sierra Nevada. As the glaciers feeding it retreated and the regional climate dried, Lake Lahontan shrank over thousands of years into its modern remnants. Pyramid Lake, forty miles north of Reno, is one of them. Walker Lake, to the southeast, is another. The Black Rock Desert playa, where Burning Man is held each year, is the exposed, perfectly flat bottom of a former Lahontan sub-basin, its surface level to within one meter across hundreds of square miles because still water levels everything it touches.

The Washoe and Paiute peoples who lived in this landscape understood it as sacred, complex water country. The tufa formations that rise from Pyramid Lake, the pyramid-shaped rock that gave the lake its English name, are calcium carbonate structures that form underwater at the mouths of freshwater springs, left standing as the lake surface fell. They are monuments, in a sense, to a world that existed before the one you are driving through.