When One River Captures Another...

The Grand Canyon of the Colorado River, not far from
where river capture occurred 16 million years ago

There's nothing like a glimpse of geologic time to make you whisper or shout "Hallelujah!"

Here's a report by John Schwarz in the New York Times about how a small river in Alaska, the Slims River,  was captured by another river, the Alsek River in four days in 2016, reversing its course.

https://www.nytimes.com/2017/04/17/science/climate-change-glacier-yukon-river.html?_r=0

Here's another report by Hannah Devlin in The Guardian:
https://www.theguardian.com/science/2017/apr/17/receding-glacier-causes-immense-canadian-river-to-vanish-in-four-days-climate-change


I knew that this had happened to two rivers I love:

• The Gunnison River near Grand Junction, Colorado, was captured by the Colorado River, leaving behind the riverless Unaweep Canyon.
• The Colorado River just east of the Grand Canyon once flowed north into the Great Salt Lake, but about 16 million years ago, the lower and western portion of today's Colorado River captured the upper Colorado River, which with the Little Colorado River had been flowing north.  "...the lower Colorado River captured the ancestral upper Colorado River and the Little Colorado in the vicinity of the present confluence of the Little Colorado and Colorado rivers."

But it's shocking to see a river capture occur in a few months in 2017, rather than millions of years ago.

Other strange things that rivers do in Utah:

http://geology.utah.gov/map-pub/survey-notes/glad-you-asked/why-does-a-river-run-through-it/