An article in the April 11, 2012 edition of the Inlander (1), written by Nicholas Deshais, describes the flooding:
Anyone unfortunate enough to be standing in what is now Spokane the day the floods came would have seen a muddy torrent hundreds of feet tall rushing at 60 miles per hour into the Spokane Valley from Rathdrum Prairie.
Deep waters submerged the Valley, scouring the ground. The landmark knobs of black basalt that dot the region were unearthed by the floodwaters.
"We think this was the largest flood ever to have occurred on our planet," says Patrick Burkhart, a geologist from Slippery Rock University in Slippery Rock, Penn. "The scale was almost unearthly, practically impossible to imagine and describe."
Geologist J Harlen Bretz first recognized evidence of the catastrophic floods, which he called the Spokane Floods, in the 1920s. Bretz's views were initially discredited. However, as the nature of the Ice Age was better understood, Bretz's original research was vindicated, and by the 1950s his conclusions were also vindicated. (7)
The flooding scoured the areas buttes, basins, and scablands. (4) Palisades Park was scoured into the cliffs you see today as a result of these huge floods. The basalt rock layers that form the cliffs are part of the wide Columbia River Plateau lava flows. (6) They formed from volcanic eruptions that occurred 17–14 million years ago. The flooding exposed these lava flows, laying bare the many layers of basalt.
Questions: As you stand looking over the valley why do you think these basalt cliffs survived the destructive floodings?
FTF Congratulations to schwandt!