THE ICE AGE FLOODS AND CHANNELED SCABLANDS
The broad rocky expanse that follows the course of Highway 395 from Pasco and Franklin County to Spokane follows one of the principal lobes of the Northwest’s legendary Channeled Scablands. In some places the terrain resembles an alien landscape with evidence of unimaginable cataclysm that evoke visions of continental wrath. The region contains some of the Western Hemisphere’s oldest evidence of human habitation including the remains of Marmes Man (c. 11,500 years ago) in eastern Franklin County, and Kennewick Man (c. 9,500 y. a.), and has been extensively studied by scientists investigating origins of similar features on the surface of Mars.
But the term “scabland” is an unkind name obscuring this land’s zephyred melodies and mysteries. The grassy slopes and rocky canyons are alive with biological diversity in spite of gargantuan prehistoric assaults. This unique terrain was formed after the recurrent build up and failure of massive ice dams near the mouth of the Clark Fork River in northern Idaho that had created enormous glacial Lake Missoula over many thousands of years. The lake grew to cover as much as 3,000 square miles across western Montana and contained approximately six hundred cubic miles of water—larger than Lake Erie!
PREHISTORIC LAKE LEWIS
When pressure and melting due to a warming trend caused the ice dam to break, the lake surged into an explosive flood, termed a “joekulhaup,” that may have drained the lake in forty-eight hours releasing a volume of water larger than in any similar event indicated on the planet. Unable to contain such volume in the Columbia’s ancient canyon course, the onslaught of Ice Age flooding tore across the soft rolling grasslands, which were violently “scabbed” or cut to bedrock, and formed three major drainages across the Columbia Plateau.
As the unimpeded waves sought declivities for escape, a peripheral branch of the eastern flow engorged what was likely an insequent streambed to form a torrential trench carving grandiose pavilioned walls, and churned out the lower Palouse River canyon. The ancestral Palouse River ran through Washtucna and Esquatzel Coulees to present Connell. The torrid waters sped at seventy-five miles an hour to engorge the lower Columbia River at present Pasco and were temporarily impounded behind Wallula Gap. Here the waters backfilled the Pasco Basin to form 3,000 square mile Lake Lewis to a height of 900 feet so only the highest points of Badger Mountain and Rattlesnake Mountain (Lalíik: DzHigh Placedz) were above water. According to ancient tribal lore, people living here at that time found refuge on these places.