How did a river cut such a gorge through a basalt mountain. Maybe it didn’t. The Yakima River originates high in the Cascade Mountains. The upper end of the river was not part of the great Missoula floods that covered Eastern Washington. The Yakima meanders through several Basalt Ridges. The nature of a meandering steam is that it flows through a relatively flat plain. If the mountains were there first, the river would have flowed around them. So how did the Yakima get through the mountains. Maybe the river was there first, As the ridges slowly developed as part of the Yakima fold formations, the river could have gradually cut a channel through its original riverbed route.
I spent a day slowly driving through the Yakima River Canyon. I stopped and photographed several interesting rocks and formations. During the next week or so, I will post several of my images.