The Columbia River has been carved up by more than a dozen dams over the past century. But it’s the colossal floods and lava flows from millions of years ago that truly set it on its winding path.  How do we really know what we know about the Columbia?   To better understand this history, Cascade PBS’s resident historian Knute Berger joined forces with geologist Nick Zentner of Nick on the Rocks in a recent episode of the Mossback’s Northwest video series. But there’s much more left to unearth.  In this episode of Mossback, Berger joins co-host Stephen Hegg to discuss his decision to spend half of this past season of Mossback’s Northwest on different aspects of the Columbia River. They also dig into the massive floods and lava flows that made the Columbia River what it is today; what it was like for Berger to work with Zentner on this project and other geological inquiries over the years; and the enthusiastic response from viewers, including one observation of a mistake in the video that led Berger down an entirely new path.  For more on all things Mossback, visit CascadePBS.org. To reach Knute Berger directly, drop him a line at knute.berger@cascadepbs.org. And if you’d like an exclusive weekly newsletter from Knute, where he offers greater insight into his latest historical discoveries, become a Cascade PBS member today. --- Credits Hosts: Stephen Hegg, Knute Berger Producer: Sara Bernard Story editor: Sarah Menzies