How did the Green River flow "uphill" for about 100 miles?

[Glenn MacGrady]

Many canoeists have paddled the Green River, which is the Colorado's largest tributary. We have trip reports of the Green on this site. But did you know there is:

". . . an American mystery which has baffled geologists for a century and a half: How did a river carve a path through a mountain in one of the country's most iconic landscapes? Scientists have long sought an answer to this question of how the Green River, the largest tributary of the Colorado River, managed to create a 700-meter-deep canyon through Utah's 4km-high Uinta Mountains instead of simply flowing around them. The question is particularly confounding because, while the Uinta Mountains are 50 million years old, the Green River has been following this route for less than 8 million years."

New research suggests this can be explained by ""lithospheric dripping" of the Uinta Mountains. I don't quite understand this, but it seems to posit that entire mountain ranges can bounce down and then back up.

https://phys.org/news/2026-01-geologists-mystery-green-river-uphill.html

Then, of course, there's the theory that the entire Colorado River once flowed in the other direction.

Ancient Colorado River Flowed Backwards

An ancient river roughly the size of today's Colorado River once flowed from California's Mojave Desert northeast through Arizona and Utah, in the opposite direction of the modern Colorado River, a new study finds.

www.nbcnews.com

Wouldn't it be simpler if rivers and mountains (and lakes, of course) would stay in their "natural" state?

 

[Alan Gage]

I've been getting into geology over the last few months and have heard some about this. I don't think there remains much question of how it carved a path through the mountains rather than going around them. Multiple very high mountain ranges were created in that area and after millions of years of erosion the valleys had filled in and buried what remained of the mountains, leaving an essentially flat landscape. More millions of years later the area began to be uplifted and what were broad and slow moving rivers with little elevation change began to flow faster and stronger. As the landscape continued to be uplifted the rivers continued removing more and more of the accumulated debris as they dug deeper channels. Eventually they reached the buried mountains and began to cut vertically down through them. Over more millions of years we ended up with what we have now: The buried mountains have been mostly excavated and now rivers run straight through them.

When mountain ranges are created they are obviously very heavy and they can cause the mantle to slump and the area can lose elevation. As they become more and more eroded the mantle can begin to rise back to "normal" levels and cause the area to uplift. Other forces can cause uplift as well. I believe this is also happening in the Canadian shield. The land had dropped under the weight of the glaciers and it's still rebounding after the glacier melt.

TLDR: The rivers didn't punch through the mountains, they wore through from the top down at a time when the mountains already existed but were buried in debris.

Alan

 

[Steve in Idaho]

Fascinating.
Flaming Gorge and the Uintas are awesome.

From the second article...

The modern Colorado River's headwaters are in the Rocky Mountains, flowing southeast to the river's mouth in the Gulf of California.

Oops.

 

[Glenn MacGrady]

From the second article...

"The modern Colorado River's headwaters are in the Rocky Mountains, flowing southeast to the river's mouth in the Gulf of California."

Oops.

Well, what do you expect. The second article is from the lamestream media (NBC), while the first is from a physics journal.

 

[Glenn MacGrady]

I don't think there remains much question of how it carved a path through the mountains rather than going around them. Multiple very high mountain ranges were created in that area and after millions of years of erosion the valleys had filled in and buried what remained of the mountains, leaving an essentially flat landscape.

Alan, I recall you are watching some geology courses, but I believe the phenomenon you are describing—mountains that silted over with debris and hence became flat land—is one of the theories that the brand new (February 2026) "lithospheric drip" hypothesis rejects. As the author of the study says in the Phys.org journal I first linked (italics mine):

"This is a long paper, because we wanted not just to lay out the case for a lithospheric drip creating the route of the Green River but also to acknowledge some previous theories. The evidence we've collected strongly contradicts the idea that the river predated the mountains, or that sediment deposits might have built up enough for the river to overtop the range, or that erosion from the south of the mountains captured the Green River."

The hypothesized geological phenomenon seems to be solely a subsidence of the surface (mountains) caused by a heavy mineralized "drip" in the crust below the mountain root, followed by rebound of the surface (mountains) when the crustal drip breaks off, rather than having anything to do with erosion or silting of the original Uinta Mountain range.

 

[Steve in Idaho]

Now I can't get the lava lamp image out of my head.

 

[Glenn MacGrady]

Now I can't get the lava lamp image out of my head.

Ah, nostalgia . . . for us 1960s and 70s geezers who furnish our tents, if not our canoes, with lava lamps, bean bag chairs and shag carpets.

 

[VA paddler]

Ah, nostalgia . . . for us 1960s and 70s geezers who furnish our tents, if not our canoes, with lava lamps, bean bag chairs and shag carpets.

That’s heavy, man…

 

[ppine]

Is this a joke? Rivers maintain their downstream flow because diastrophism, uplift is slower the river's ability to erode and downcut its river path.

 

[Halpc]

Very interesting discussion on River/canyon formation. The scope of time- millions of years- and the physical size of the mountains and canyons is truly mind boggling. Despite living near the Uintah mountains, I had never heard of this theory. Thanks for posting it.

 

[Alan Gage]

Alan, I recall you are watching some geology courses, but I believe the phenomenon you are describing—mountains that silted over with debris and hence became flat land—is one of the theories that the brand new (February 2026) "lithospheric drip" hypothesis rejects. As the author of the study says in the Phys.org journal I first linked (italics mine):

I took the time to read the article now and it sounds interesting. The book I read that talks about the geology of that area, and explains how they believed the rivers cut through mountain ranges was written in the 80's or 90's so there could certainly be new information that's come to light since then.

Here's a short video from a geology professor explaining that hypothesis:

@Steve in Idaho you might like his channel. He teaches in Idaho and has a lot of videos explaining the local landcape and geology.

 

[Steve in Idaho]

Thanks, @Alan Gage . I subscribed to his channel.

 

[Glenn MacGrady]

Here's a short video from a geology professor explaining that hypothesis:

The professor in the video seems to be advancing a hypothesis that is somewhat different from the lithospheric drip hypothesis, since he doesn't really focus on a subsidence of the mountain range caused by a heavy drip formation in the crustal mountain range root, followed by a re-uplifting of the mountain range after the drip separates and drops off into the mantle (?). Who know which of the hypotheses are right, as they all sound reasonable.

I was impressed by the scenic beauty of the Green River and the canyon, and would love to paddle that river if I ever get to the West again. I still have bucket list river fantasies, but they never include portage-heavy trips.