We must begin by remembering beyond history.
—Paul Shepard, Coming Home to the Pleistocene
THE TOWN of Missoula, Montana, begins when a steep fifty-mile corridor of pine, fir, and tamarack ends, at the site where the Clark Fork River exits Hellgate Canyon. French fur-trapping voyageurs called this confluence Port d’Enfer, or Port of Hell. In their own language, the Salish called the area “the river of ambush/surprise” or “place of rushing water,” stitched together by white settlers into Nemissoolatakoo, which is how we think Missoula found its name. In the early 1800s, the Lewis and Clark expedition passed through the area heading west. On their return near Pine Creek, Idaho, along modern-day I-90, Meriwether Lewis named the Clark Fork “in honour of my worthy friend and fellow traveller,” giving the ancient river its contemporary name. Where the Clark Fork River spills out of Hellgate Canyon into Missoula today, a university town sprawls.
A palimpsest is a manuscript on parchment where the original text is scraped away and replaced by new text. The first layer, imperfectly erased, seeps through into the next, making traces of itself visible. With or without us, landscapes are rarely different. No matter how many layers or erasures take place, the past seeps through.
During the last ice age, the Clark Fork poured into a valley blocked by an ice dam. Where the dam blocked the river, near Sandpoint, Idaho, the valley filled in, creating a prehistoric lake with a volume equivalent to Lakes Erie and Ontario combined. When that ice dam burst—an estimated 80 to 120 times over thousands of years—each rupture was a biblical deluge. The floods carved, over and over again, the Columbia River Gorge on the Washington and Oregon border 450 miles away. They scraped the Scablands in eastern Washington down to bare rock, leaving ripple marks and potholes visible from outer space. Linear strandlines that mark centuries of changing water levels are terraced into the surrounding hills of Missoula today.
One mammoth expert claimed that after each flood, the Columbia River “carried several times more water than all the rivers in the world combined.” I want to know what else it carried. Topsoil, icebergs,
