Some of the largest cataclysmic geologic events on earth occurred in what is now the Pacific North West. About 11 million years of volcanic flow activity, ending about 6 million years ago, created the Columbia Plateau with basaltic lava formations up to two miles deep. This huge basaltic plateau covering much of Eastern Washington and Oregon and adjacent parts of Idaho was later inundated by massive Ice Age floods ending about 15,000 calendar years ago. The scale of these events has been seldom seen elsewhere as it carved a landscape that appears other worldly. (In fact, the resulting terrain so closely matches that seen on Mars that NASA tested the Sojourner robotic rover here before its 1997 mission to Mars.
Scablands from basalt and flooding
The Columbia River continues to cut into basalt
As many as 100 floods deposited layers of sediment atop the basalt that today provide the soil for growing some of the best wine grapes and hence wines in the country and in some cases, the world. These are the wines of Oregon and Washington State.