Our Northwest

Channeled scablands road trip, part 2

Tuesday, May 6, 2014by  Jon Osterberg

Even in rainy Washington, it’s not often that you drive with your wipers on high speed.
   But barrelling down I-90 toward George, Wash., I drove into a black-cloud deluge that required it. Rain pooled an inch deep on the road surface.
   Ironic, me hydroplaning on the freeway while driving to visit Ice Age flood features.
   This was the last leg of my April 25 drive home from Kennewick, which already had taken me on a roundabout route through Eastern Washington’s channeled scablands.
   I exited I-90 at Silica Road and turned west onto the Old Vantage Highway, which until October 1962 had been known as the Sunset Highway, U.S. 10. Within a quarter-mile I dropped into the head of vast Frenchman Coulee.
   When Glacial Lake Missoula burst through its ice dam eons ago, a torrent of water gushed southwest from Clark Fork, Idaho, across Rathdrum Prairie and into Eastern Washington. Hundreds of feet high, these floodwaters raced at 60 mph, ripping apart basalt bedrock and carving coulees and potholes. The primary flood channels included the Cheney-Palouse tract, Crab Creek, Drumheller Channels, and the northern tract that flooded Dry Falls and the Quincy Basin.
   When Quincy Basin floodwaters butted up against the Frenchman Hills west of Moses Lake, they paralleled the hills and rushed down the tilted Columbia Plateau, forming massive, broad cataracts that eroded columnar basalt and carved cliffs and coulees. Potholes Coulee near Quincy bears striking evidence of this. So does Frenchman Coulee.
   Water cascaded over steep cliffs and formed a flat flood plain on the Frenchman Coulee floor, which led to the Columbia River. Frenchman is actually a “dual coulee,” separated from neighboring Echo Basin by a long rib of basalt called the Sunshine Wall. When I took this photo the rain had stopped, and filtered sunshine brightened Echo Basin’s ancient cataract walls.
   I drove to where the road disappears on the riverbank and doubled back, climbing Frenchman Coulee’s south wall. I easily could envision water surging over these basalt cliffs and flooding the coulee floor. Far away, near the head of the coulee, I saw a tiny waterfall dropping from nearby Hilltop Lake – a miniscule reminder of the Ice Age floods.
   At the end of the Sunshine Wall the pavement bends, and there the setting sun illuminated The Feathers, a lone remnant of columnar basalt stripped of its surroundings by floodwaters. Rock climbers flock here year-round.
   And abruptly, Frenchman Coulee ended. I drove past the ruins of a long-abandoned gas station and merged onto I-90, headed home for the Puget lowlands, a region never scoured by floods like those that carved the channeled scablands.

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