The Spokane-to-Portland leg of Amtrak’s Empire Builder route is a scenic day trip that runs through two geologic wonders: flood basalts and the Columbia River Gorge, carved out of that basalt by giant Ice Age floods.
When I visited the gorge this spring, the usual chatter in the lounge car tapered into silent awe as we rolled through the scenic landscape that fire and ice have left along the Columbia River.
That late March day dawned clear and bright as we left Pasco, Washington – the halfway point of the run – bound for Portland, Oregon. Its neat streets and rail yards were unremarkable, but in spite of the dry climate in the Cascades rain shadow, many orchards were in bloom along the track south and west of the city.
The real journey to wonderland started later when dark rock began to poke up out of the prairie. Soon cliff lobes made out of the same material – basalt – appeared in the distance. It went on mile after mile, farther than any lava flow I’ve ever seen before.
I didn’t know it then, but people call this region the scablands. Most of its soil has been stripped away – only prairie grass grows on it now. The underlying basalt there has been scoured into long lobe-shaped ridges or deep stepped canyons.
It’s a strange-looking country, but not a desert. Small herds of Black Angus cattle graze amid the sage. Gigantic white wind turbines stand on some of the hills.
We were at the northern bank of the Columbia River before I knew it. Here the basalt forms cliffs of alternating layers of columns and broken rock that are piled up hundreds of feet high.
Across the Columbia River, on the Oregon side, are matching cliffs. From a distance, they are flat-topped and rocky. Behind them, gentle grassy slopes run up more than a thousand feet above the valley further inland.
A few stony islands rise out of the river here and there. Their smoothly rounded edges are as dark as the cliffs, and only grass and scrub grows there. The largest island, Memaloose, east of Bingen-White Salmon, was used as a burial ground by the Chinook tribes.
As you roll along, it all starts to get to you – the rounded curves on any rock facing north and east; the columnar basalt, marked with green or mossy yellow-white wherever struggling life has found a way to survive; the frozen lava heaped up, layer upon layer, into the blue morning sky; the immensity of the chasms, greater even than the wide river that flows through them.
Conversation fades away as everyone concentrates on the spectacle beyond the windows, knowing we are seeing something found in very few places on Earth.
All this dark rock is part of the Columbia River flood basalts. Such continental flooding has only occurred in a few places on Earth – in the Deccan Traps of India and in Russia’s Siberian Traps.
It also happened in what is now eastern Washington, as well as in Idaho, Montana, Oregon, (and Nevada?) millions of years ago. Runny, Hawaiian-style lava poured out through ground fissures above the volcanic hot spot that now sits today under Yellowstone. The eruption went on for 11.5 million years, eventually covering over 81,000 square miles of Washington, Idaho, and Oregon.
After it was over, and long after the lava cooled, the plain was shaped by regional geology processes and a new river, the Columbia, eventually found its way through to the Pacific, flowing through forested valleys that had gently sloping walls.
Then, near the end of the last ice age, came a series of massive floods that stripped vegetation and soil down to bedrock, forming the scablands. The deep, turbulent water also tore out columns and chunks of basalt as it passed through, turning valleys into steep-walled gorges and scouring smooth the stony surfaces of islands and low-topped hills that we see along the Columbia River Gorge today.
Once that ice age was over, some 11,000 years ago, the floods finally ceased. The scarred land could now begin to heal in peace.
My 21st-century train ride gave no hint of the violence that shaped this scenic river valley.
Besides the scablands and the Columbia River Gorge, there were other natural and mandmade wonders, including distant views of Mount Hood and, closer to the river, giant powerlines marching along the hillsides above Horsethief Lake where the Columbia River backs up behind the Dalles Dam.
After four tunnels through the basalt, our train reached Wind Mountain, a 2500-foot-high cone-shaped mountain that marks the dividing line between the Cascades rain shadow to the east and the Pacific Northwest rainforest to the west. In the blink of an eye, we were among conifers and tall hardwoods that hid most of the telltale signs of the area’s tumultuous history.
It only takes four hours to travel from Pasco to Portland on the train. Leave the driving to Amtrak, sit back and enjoy a scenic tour of the scablands, the Columbia River flood basalts and the beautiful Columbia River Gorge – unique geology that formed in fire and ice.
- David Alt. Glacial Lake Missoula and its Humongous Floods. Mountain Press. Missoula. 2001
- Columbia River Basalt Province. Kristen Straub and Paul Link, Idaho State University
Categories: Random thoughts